# Wiseco Piston and Hybrid Ceramic Bearings from Dominant Saws for 372XP



## blsnelling (Sep 27, 2015)

I big thank you goes out to Dominant Saws. They have sent me one of their Wiseco 372 pistons and a set of hybrid ceramic bearings. I plan to put the piston in my "new" 372. I don't remember if I put ceramic bearings in this saw or not. If not, the bearings will be going in this saw as well. I haven't yet made any measurements, but here are pics of the items.


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## Jacob J. (Sep 27, 2015)

Interesting Brad- did they send you the parts to demo? I've been eyeballing those pistons for a while now.


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## Jacob J. (Sep 27, 2015)

BTW- it says "50cc" on the box, so don't build your engine too big.


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## Locust Cutter (Sep 27, 2015)

Interesting...


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## RedneckChainsawRepair (Sep 27, 2015)

Jacob J. said:


> BTW- it says "50cc" on the box, so don't build your engine too big.



 noticed that too. cc instead of mm


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## blsnelling (Sep 27, 2015)

Jacob J. said:


> Interesting Brad- did they send you the parts to demo? I've been eyeballing those pistons for a while now.


Yes. Do you know what P to C clearance should be? I'm hoping to avoid the scuffing I encountered with the 066 Wiseco piston I tested from Baileys.


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## MustangMike (Sep 27, 2015)

I ran ceramic bearings in my bike crank, but I think you will be encountering a few more RPMs!!!


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## Rx7man (Sep 27, 2015)

Nice looking stuff!.. cost?


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## blsnelling (Sep 27, 2015)

MustangMike said:


> I ran ceramic bearings in my bike crank, but I think you will be encountering a few more RPMs!!!


I have run ceramic bearings in a couple other saws with good results. It's critical to use those with black Si3n4 balls, not the white ZrO2 balls. The ZrO2 balls will fail within a tank or two. I have run hybrid ceramic bearings with Si3n4 balls for several years in a high RPM 346XP with no issues at all. I also have them in my piped 390XP.


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## Locust Cutter (Sep 27, 2015)

Soooo..... If you found a basket case 390xp and were going to rebuild it, would you spend the extra$$$ to split the cases and use these bearings, even if the original bearings were still good (under the mantra of do it right the first time)?


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## blsnelling (Sep 27, 2015)

Ceramic bearings are not needed for 99.9% of saws. I've been told by a race saw builder that their only real advantage over a standard bearing is that they don't require break-in. For most saws, your just as well off to go with an inexpensive set of quality bearings with C3 clearance ratings. With that said, I can tell you that these bearings are SMOOOOOOOOOTH!!! I didn't know the bearing were coming with the piston, and couldn't readily see what the balls were made of. Once I spun them, I figured they had to be ceramic. I then found the note in the package stating that they were. A set of bearings like this will run you about $100.


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## gunnusmc03 (Sep 27, 2015)

Rx7man said:


> Nice looking stuff!.. cost?



Piston is $150


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## Rx7man (Sep 27, 2015)

I figured it would be expensive.. but I will say it looks very nicely finished.. you get what you pay for.

Back in my Rx7 days, I put about $10,000 into an engine, best of everything went into it, additional dowel pins, apex seals that cost $200 each (x6), and lots and lots of porting... I didn't own it long enough to push it to it's limits by far.. but it made 375 RWHP at just 11 PSI of boost... and a buddy of mine with a very similar engine did push his to the limits.. he got 875 RWHP at 48 PSI on race gas from 1.3L.. he also daily drove it (at about 500 rwhp pump gas) and it lived for about 50,000 miles.. The castings gave out and cracked at that point.

Power, Reliablility, Cost. Pick 2!


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## blsnelling (Sep 27, 2015)

The box states clearance should be only .0010". That just doesn't seem like enough to me, especially when we're dealing with a forged piston that will expand significantly more than a stock cast piston. @Jacob J. or @leeha , what kind of clearance have you guys seen work well with Wiseco pistons?


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## mdavlee (Sep 27, 2015)

.003" would be better. Probably have to let it warm up good before burying it in wood if it's truly .001"


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## blsnelling (Sep 27, 2015)

I've got a nasty old 372 jug setting out in the garage with most of it's fins broken off. It has a great bore though. I think I'll go throw it in there and see what it is.


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## strtspdlx (Sep 27, 2015)

Less then .003 from my dirt bike days is what I was always told. Anymore and wiseco pistons had an annoying piston slap. 


Regards-Carlo


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## blsnelling (Sep 27, 2015)

Using a snap gauge and micrometer, the bore measures 1.969" and the piston measures 1.967" at the bottom, center of the skirt. Using a feeler gauge, it has a tight .002" clearance at the bottom of the skirt, exactly the same as a new Meteor 50mm piston for a 044. The big difference is in the diameter at the crown. The Meteor piston measures 1.961" and the Wiseco measures 1.955", leaving a lot more room for expansion where the piston gets the hottest. I also noticed that the Wiseco is .002" smaller, 1.965", across the diagonal of the skirt corners. The Meteor is consistent at 1.967" at all points around the skirts.

According to what I found online, the minimum ring gap should be .008"-.010". I've got .011". 

Hopefully my 372 cylinder is no smaller, and hopefully just a hair bigger.


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## Jacob J. (Sep 27, 2015)

blsnelling said:


> Yes. Do you know what P to C clearance should be? I'm hoping to avoid the scuffing I encountered with the 066 Wiseco piston I tested from Baileys.



I'm running a Bailey's Wiseco piston in one of my 372s...the gap I had averaged around 0.0020-0.0025" or so with my old Snap-on feeler gauges. I'm running it in a later "B" cylinder, which usually have a little more clearance than an A cylinder. Even with as small a bore as 50mm- I don't think I would run it as tight as 0.0010".


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## blsnelling (Sep 27, 2015)

Another interesting measurement was that the crown is 0.150" thick at the edge. Most pistons are only 0.135" or less. The popup is an additional .038" tall. Lots of room there for additional popup making.


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## mdavlee (Sep 27, 2015)

I'm interested to see how much compression it will make. I think I'd still rather have a flat top.


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## blsnelling (Sep 27, 2015)

IMHO, popup vs flattop is much ado about nothing. Here are two 661s built identically, except one has a popup and one a cut squishband. The one with the popup holds more RPMs in the cut, even with a heavy load. Add to that, that I had forgotten to add bar lube to the saw with a popup. Yes, I pulled a Wiggs, lol


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## bwalker (Sep 27, 2015)

blsnelling said:


> Yes. Do you know what P to C clearance should be? I'm hoping to avoid the scuffing I encountered with the 066 Wiseco piston I tested from Baileys.


Many a guy has had that problem with Wiseco pistons. The nick name for them is Seizco. 
I really like them. They are tough as nails and when clearanced correctly work great. The also will no crack a skirt like a cast piston if the p to c clearance opens up from wear.


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## mdavlee (Sep 27, 2015)

blsnelling said:


> IMHO, popup vs flattop is much ado about nothing. Here are two 661s built identically, except one has a popup and one a cut squishband. The one with the popup holds more RPMs in the cut, even with a heavy load. Add to that, that I had forgotten to add bar lube to the saw with a popup. Yes, I pulled a Wiggs, lol



Is this a drop in or will you have to cut the base for ideal squish? I was just thinking of it doesn't work and you had to go back to a flat top.


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## bwalker (Sep 27, 2015)

blsnelling said:


> IMHO, popup vs flattop is much ado about nothing. Here are two 661s built identically, except one has a popup and one a cut squishband. The one with the popup holds more RPMs in the cut, even with a heavy load. Add to that, that I had forgotten to add bar lube to the saw with a popup. Yes, I pulled a Wiggs, lol



I'd much prefer a uncut piston with a machined squish. One area I think saw builders are missing the boat and one that nets pretty large gains is adjusting the angle and width of the squish band.


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## blsnelling (Sep 27, 2015)

I believe this piston is intended to be a drop-in. I don't think this 1/2 finless jug I have has been touched, so I will test that out.


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## blsnelling (Sep 27, 2015)

bwalker said:


> I'd much prefer a uncut piston with a machined squish. One area I think saw builders are missing the boat and one that nets pretty large gains is adjusting the angle and width of the squish band.


Not much you can do about the width.


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## mdavlee (Sep 27, 2015)

blsnelling said:


> I believe this piston is intended to be a drop-in. I don't think this 1/2 finless jug I have has been touched, so I will test that out.


If that's the case then I'd give one a try.


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## blsnelling (Sep 27, 2015)

http://www.ebay.com/itm/Dominant-Sa...-50mm-Husky-/121770823546?hash=item1c5a1b4f7a

"They are direct replacement and significant upgrade to the OEM 50mm piston. Single, thin 1mm, chrome ring, lighter weight 7g less, and lower thermal expansion (higher silicon and only Wiseco know the numbers) add up to a piston many times better than OEM or other replacements. These have domed crowns for boosted compression and improved in cut rpms."


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## super3 (Sep 27, 2015)

bwalker said:


> I'd much prefer a uncut piston with a machined squish. One area I think saw builders are missing the boat and one that nets pretty large gains is adjusting the angle and width of the squish band.



You need to catch up on what's being done lately. 



blsnelling said:


> Not much you can do about the width.




The deeper the cut, the wider it gets.


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## mdavlee (Sep 27, 2015)

Is the skirt longer or any other things better?


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## bwalker (Sep 27, 2015)

blsnelling said:


> Not much you can do about the width.


Not easily, granted. It would seem to me you could set squish angle to your desired measurement, then come in with a different tool and set the width and cut the chamber to more of a hemisphere shape.


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## blsnelling (Sep 27, 2015)

Then you defeat a big part of why you cut the squishband, increasing compression. We'll save this for another thread though. Yes, I know I started the derail, lol.


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## bwalker (Sep 27, 2015)

blsnelling said:


> http://www.ebay.com/itm/Dominant-Sa...-50mm-Husky-/121770823546?hash=item1c5a1b4f7a
> 
> "They are direct replacement and significant upgrade to the OEM 50mm piston. Single, thin 1mm, chrome ring, lighter weight 7g less, and lower thermal expansion (higher silicon and only Wiseco know the numbers) add up to a piston many times better than OEM or other replacements. These have domed crowns for boosted compression and improved in cut rpms."


I would find it very interesting if this piston had both a higher silicon content and was lighter than stock. Wiseco pistons have always been heavier than the stock pistons they replaced IME. Not that that's a bad thing. They take abuse that will crack a stock piston in short order.. However they don't seem to deal with heat as well and melt easier than a cast piston.


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## blsnelling (Sep 27, 2015)

I will definitely put it on a scale. It feels heavier in the hand.


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## bwalker (Sep 27, 2015)

blsnelling said:


> Then you defeat a big part of why you cut the squishband, increasing compression. We'll save this for another thread though. Yes, I know I started the derail, lol.


Granted, and testing would have to be done to see if the trade off was worth it. Maybe the best thing woukd be a popup and chamber like I suggested?


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## bwalker (Sep 27, 2015)

blsnelling said:


> I will definitely put it on a scale. It feels heavier in the hand.


I have personaly never seen a Wiseco that's lighter than stock. And I have used them quite a bit, including their single ring race pistons.


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## backhoelover (Sep 27, 2015)

all this talking about saws


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## Moparmyway (Sep 27, 2015)

Brad, your pop-up 661 is simply astonishing !!
Great job !!!
Any idea what RPM's she was turning

Please dont forget to make that new thread ................ i will be watching for it !!


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## blsnelling (Sep 27, 2015)

Moparmyway said:


> Brad, your pop-up 661 is simply astonishing !!
> Great job !!!
> A*ny idea what RPM's she was turning*
> 
> Please dont forget to make that new thread ................ i will be watching for it !!


No. My tach doesn't work on this saw.


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## jmssaws (Sep 27, 2015)

I used to only build popup saws and have only cut the squish band for a couple years and on most saws i can't tell a difference but if your exhaust is 95 stock a popup ain't fixing that. In my motorcycle engine days we used wiesco and never had any problems.


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## Rev (Sep 27, 2015)

Holy good golly, I go out of my way to try and make pistons that look like that...wow..


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## Rx7man (Sep 27, 2015)

Brad, take a video of the saw and analyze the frequency in a sound program.. That's what I've resorted to for now, and it works alright.. 100 hz is 6000 RPM, 200 is 12,000, etc


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## Moparmyway (Sep 28, 2015)

blsnelling said:


> No. My tach doesn't work on this saw.


A wired tach should work (my Hardline tach is wired to mine and works)........... I will see if my TT-20K works on its wire harness if you want


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## blsnelling (Sep 28, 2015)

jmssaws said:


> I used to only build popup saws and have only cut the squish band for a couple years and on most saws i can't tell a difference but i*f your exhaust is 95 stock a popup ain't fixing that.* In my motorcycle engine days we used wiesco and never had any problems.


I cut the squishband on 066/660s.


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## idiotwithasaw (Sep 28, 2015)

Is the dominant logo on the piston on there permanently, or is it a decal that must be removed?


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## David Young (Sep 28, 2015)

idiotwithasaw said:


> Is the dominant logo on the piston on there permanently, or is it a decal that must be removed?


looks like a molybdenum coating that will wear off.


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## mdavlee (Sep 28, 2015)

If say the logo won't last too long after starting it,


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## idiotwithasaw (Sep 28, 2015)

I just thought that since this is essentially a racing piston if it was supposed to serve as a kind of wear gauge. When so much of the logo was gone to replace the piston. Or is it just to be pretty.


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## Grits & Gravy (Sep 30, 2015)

I've ran 60+ mm wiseco's as tight as .0013" on the clearance in air cooled kart engines turning WAY past 15k... But you'd better be vigilant about warmup.


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## blsnelling (Mar 13, 2016)

After more than 5 months, I finally have a test bed for these bearings and Wiseco piston from Dominant Saws. This beautiful 2171 has some pretty cool internals.

This saw lived it's previous life as a rescue saw from Cutters Edge. Unbeknown to me, the PTO side crank seal had badly wallowed out the case, and the crank was damaged as well. I put it back together with a new OEM case and a good used OEM crank. Squish was .037" so the cylinder base was cut .017", netting a final squish of .020". The exhaust port was de-carboned and polished. Otherwise, this saw is 100% stock. Initial compression after the first heat cycle was 152 PSI. After a little run time, and as time permits, I'll be going back in to fully mod this saw. After the first couple heat cycles, the piston looks great, as seen below.


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## SCHallenger (Mar 13, 2016)




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## Definitive Dave (Mar 13, 2016)

Nice


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## Full Chisel (Mar 14, 2016)

That looks cool with the logo showing through the ex. port...those are some nice looking pistons!

You guys are smart...and stuff.


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## Jon1212 (Mar 14, 2016)

blsnelling said:


>



Dayum! I wish I had the extra coin, I'd offer to buy that saw off of you as it sits.


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## bwalker (Mar 14, 2016)

Brad, what is the weight of the forged Wiseco vs the stock cast piston?


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## blsnelling (Mar 14, 2016)

According to Dominant Saws, they're 7 grams lighter. The newest version is lighter yet.


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## blsnelling (Mar 14, 2016)

Jon1212 said:


> Dayum! I wish I had the extra coin, I'd offer to buy that saw off of you as it sits.


I appreciate that. If and when I do sell it, or won't be until after I'm done testing with it. That will include full mods.


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## Jon1212 (Mar 14, 2016)

blsnelling said:


> I appreciate that. If and when I do sell it, or won't be until after I'm done testing with it. That will include full mods.



Well heck. Brad we may disagree on some stuff, but I think we can agree on the fact that this saw is one of the best, and not just looking.


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## Big_Wood (Mar 14, 2016)

really cool try out of the wiseco. i'm a little disappointed the base had to be turned though and then even after being turned you only got 152psi out of it. i see more then that on 98% of the 372's i delete the gasket on. will be interesting to see if it goes up some and how it runs. you gonna make a vid for us brad?


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## BGE541 (Mar 14, 2016)

Video needed and maybe Brad can hook up a group buy for those pistons on here


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## Chainsaw Jim (Mar 14, 2016)

I wouldn't expect an extreme compression number with a single thinner chrome ring.

I do have a question after reading the instructions where it say use only on nikasil and not chrome plated bores.
Is a nickel ceramic coating covering a chrome plate or is the entire plating solution a nickel ceramic material?


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## Marshy (Mar 14, 2016)

blsnelling said:


> The box states clearance should be only .0010". That just doesn't seem like enough to me, especially when we're dealing with a forged piston that will expand significantly more than a stock cast piston. @Jacob J. or @leeha , what kind of clearance have you guys seen work well with Wiseco pistons?


I might be a little late but, you should ask Wiseco! Can't stress that enough.


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## blsnelling (Mar 14, 2016)

It survived it's maiden voyage! There appears to not be a mark on the piston, much unlike the 660 Wiseco piston I tried before. This one must be engineered and sized correctly. I'm waiting for it to cool off to get a good compression number. I'm then going back in it to cut a taller popup like I normally would.

I have it tuned a little on the rich side here to 13,000-13,200 for break-in.


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## stihlaficionado (Mar 14, 2016)

blsnelling said:


> It survived it's maiden voyage! There appears to not be a mark on the piston, much unlike the 660 Wiseco piston I tried before. This one must be engineered and sized correctly. I'm waiting for it to cool off to get a good compression number. I'm then going back in it to cut a taller popup like I normally would.
> 
> I have it tuned a little on the rich side here to 13,000-13,200 for break-in.


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## blsnelling (Mar 14, 2016)

I turned an additional .035" of popup on it. Squish is not at .018". It has to cool back off before I can test the compression again. BTW, after cooling off from the video above, compression was 148 PSI. As pointed at, this is a single and very thin ring piston. It's not surprising that static compression is down a little. With pressure on it during combustion, that ring will create a lot tighter seal, yet having much less drag and parasitic loss to friction.


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## blsnelling (Mar 14, 2016)

It's now pulling 182 PSI.


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## Big_Wood (Mar 15, 2016)

it's pulling 182 psi but what the rest of us want is for it to be a performance advantage over OEM as a drop in piston like dominant saws claim. i consider what you did significant work. really cool to finally see the outcome of this thread but i think i'll stick with meteor or OEM. i don't build race saws though so maybe this piston was meant to lure in the race crowd. i was tempted to buy one of these pistons a while back at the start of this thread but glad i didn't cause i would have been pissed if .017 needed to be taken off the base just to make squish acceptable and then see less then a gasket delete stock saw even after machining. dominant saw seem to be blowing smoke with their claims. i have used wiseco many times in dirtbikes and love them for that but that's where they're gonna stay for me. thanks for the follow up brad.


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## Chainsaw Jim (Mar 15, 2016)

westcoaster90 said:


> it's pulling 182 psi but what the rest of us want is for it to be a performance advantage over OEM as a drop in piston like dominant saws claim. i consider what you did significant work. really cool to finally see the outcome of this thread but i think i'll stick with meteor or OEM. i don't build race saws though so maybe this piston was meant to lure in the race crowd. i was tempted to buy one of these pistons a while back at the start of this thread but glad i didn't cause i would have been pissed if .017 needed to be taken off the base just to make squish acceptable and then see less then a gasket delete stock saw even after machining. dominant saw seem to be blowing smoke with their claims. i have used wiseco many times in dirtbikes and love them for that but that's where they're gonna stay for me. thanks for the follow up brad.


Unless my eyes deceived me it looks like he only removed the .017 to get the squish down to .020 and maintain the use of an oem gasket. The same thing would be necessary with an oem piston.


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## Jon1212 (Mar 15, 2016)

blsnelling said:


> It's now pulling 182 PSI.


That's a considerable gain. I need to make some shekels........

Do you think the purple shirt helped in the saw "waking up"?


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## blsnelling (Mar 15, 2016)

For what these pistons cost, they absolutely target the race/enthusiast crowd. No one else is going to pay that kind of money for a piston. I think that's understood and expected.

*There's a lot more to saw performance than static compression. *However, I think Dominant Saw isn't quite satisfied with the compression they're getting with these either. The second batch of these are not only lighter, but have a taller dome. These pistons will evolve as they gain more experience with them.

It's been a long time since I ran a stock 372, but this saw is quite impressive for only having a muffler mod and set squish. I think the static compression reading is deceptive. 

For me, the biggest performance advantage is the single thin ring. Most guys under estimate how much parasitic loss there is due to friction from the rings. It's significant! 

To me, the slightly less weight is only a nice bonus. I could be wrong. It certainly doesn't hurt! Every little piece of the pie helps.

The forged part doesn't mean a lot to me either. I don't see an issue with stock pistons breaking. But, who else are you going to get to make you a quality piston to your specs? Wiseco is an obvious choice, and forged pistons are what they do, and they do them very well.

Bottom line, I've yet to find any fault with these. Yes, they're expensive, but it is a custom made, higher performance, high quality piece. You're going to pay for that. I like the direction they're headed with the changes...just more of a good thing. Of they could get 180PSI with a drop in piston, they'd be the cat's meow, IMHO.


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## Marshy (Mar 15, 2016)

Did you ask Dominant if they expect their pistons to have increased performance as a plug and play replacement piston or do they expect some level of cylinder porting/squish cutting to unlock the potential performance gains? Seems like a large investment in a part that is "evolving" and appears to be marketed as plug and play power adder.

Also, did you request any specific specs for the piston (i.e. custom piston) or are these just their AM performance product for this saw?


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## Chris-PA (Mar 15, 2016)

That's a really cool saw, and looks really good too. The piston is neat, and I'm interested to see what advantages it might have.



blsnelling said:


> As pointed at, this is a single and very thin ring piston. It's not surprising that static compression is down a little. With pressure on it during combustion, that ring will create a lot tighter seal


As I've said before I think people associate way too much meaning on low rpm pressure readings on a gauge. It's really a diagnostic tool for determining cylinder/ring condition, and does not tell you all that much about performance or cylinder pressure under combustion conditions.


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## bikemike (Mar 15, 2016)

Why do a ceramic hybrid bearing. They are still standard races might as well spend the money and buy full ceramic bearings they can handle some crazy loads and rpm and temp. You can also run the dry and cause no harm to them


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## blsnelling (Mar 15, 2016)

http://dominantsaw.com/products/wiseco-dominant-372xp-50mm-high-performance-piston

http://dominantsaw.com/blogs/tech-a...ut-a-dominant-wiseco-piston-in-your-husky-372


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## blsnelling (Mar 15, 2016)

http://dominantsaw.com/collections/frontpage/products/ceramic-hybrid-main-bearing-set


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## Chainsaw Jim (Mar 15, 2016)

I just looked at parts tree and they list three oem Pistons from $89-$117. This wiseco piston is listed for $119.99. 
I don't think I'll be buying an oem next time.


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## LowVolt (Mar 15, 2016)

What jerk sold you a saw with a messed up case and crank?


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## Big_Wood (Mar 15, 2016)

blsnelling said:


> For what these pistons cost, they absolutely target the race/enthusiast crowd. No one else is going to pay that kind of money for a piston. I think that's understood and expected.
> 
> *There's a lot more to saw performance than static compression. *However, I think Dominant Saw isn't quite satisfied with the compression they're getting with these either. The second batch of these are not only lighter, but have a taller dome. These pistons will evolve as they gain more experience with them.
> 
> ...



I realize that compression isn't everything. Hell even a 372 with 140psi runs pretty dang good. All I was saying is for the average hack it would still be a better route to stick with OEM or meteor if there is no advantage with the wiseco. If they could make them so squish is acceptable and compression is stout around 180 like you say just as a drop in I'd have to try one.


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## blsnelling (Mar 15, 2016)

Chainsaw Jim said:


> I just looked at parts tree and they list three oem Pistons from $89-$117. This wiseco piston is listed for $119.99.
> I don't think I'll be buying an oem next time.


I consider Meteor to be OEM quality. They're like $40-$45.


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## blsnelling (Mar 15, 2016)

westcoaster90 said:


> I realize that compression isn't everything. Hell even a 372 with 140psi runs pretty dang good. All I was saying is for the average hack it would still be a better route to stick with OEM or meteor if there is no advantage with the wiseco. If they could make them so squish is acceptable and compression is stout around 180 like you say just as a drop in I'd have to try one.


Typical compression on a stock 372XP is anywhere in the 140s. 150 would be a very good one. That's just how they're made. A lot of that is due to excessive squish. I do agree that they should raise the crown height on these about .015" and increase the dome another .035".


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## blsnelling (Mar 15, 2016)

LowVolt said:


> What jerk sold you a saw with a messed up case and crank?


Some PSP loser from the east side of Cincinnati  No wonder he didn't want it!


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## Mad Professor (Mar 15, 2016)

Brad, so it really only has 0.001" clearance on P/C?

I think I remember Leeha getting some 166 slugs and they ran 0.004-0.005"


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## Chainsaw Jim (Mar 15, 2016)

blsnelling said:


> I consider Meteor to be OEM quality. They're like $40-$45.


It may very well be but it isn't an upgrade like this wiseco is. I see people in my area don't like buying saws with aftermarket parts since the reputation for the chainsaw aftermarket parts world is the opposite of the aftermarket dirt bike parts world. This wiseco piston should be a different story with the reputation the name has already earned and it should help keep the 372's resale value as good if not better than if the piston were oem.


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## Chris-PA (Mar 15, 2016)

westcoaster90 said:


> I realize that compression isn't everything. Hell even a 372 with 140psi runs pretty dang good. All I was saying is for the average hack it would still be a better route to stick with OEM or meteor if there is no advantage with the wiseco. If they could make them so squish is acceptable and compression is stout around 180 like you say just as a drop in I'd have to try one.


Probably true, though in fairness that's not the purpose of parts like this. I'm interested to see if there's any actual benefit over doing the same mods with OEM or more typical AM parts. I'm actually more impressed by the bearings than the piston, but marketing is marketing - are any of these fancy parts actually removing any limitations that would be significant in a modified work saw, or do you have to be pushing things to the limit in a race engine for any benefits to be noticeable?


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## Big_Wood (Mar 15, 2016)

Chris-PA said:


> Probably true, though in fairness that's not the purpose of parts like this. I'm interested to see if there's any actual benefit over doing the same mods with OEM or more typical AM parts. I'm actually more impressed by the bearings than the piston, but marketing is marketing - are any of these fancy parts actually removing any limitations that would be significant in a modified work saw, or do you have to be pushing things to the limit in a race engine for any benefits to be noticeable?



I know of a 372 with ceramic bearings in it and the thing has some significant run time. I've always wondered about them as well. Maybe I'll try a set one day.


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## blsnelling (Mar 15, 2016)

My previous 346 has ceramic bearings in it. I used it a fair amount for several years, then sold it to an arborist who put it into full time use.


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## Chris-PA (Mar 15, 2016)

westcoaster90 said:


> I know of a 372 with ceramic bearings in it and the thing has some significant run time. I've always wondered about them as well. Maybe I'll try a set one day.


From their ad:

_*Overall friction is more than 10% less than an all-steel bearing of the highest quality. We've seen an increase in 500 free rpm on a Husky 357. This translates into speed in the wood, under load.*_

But by definition free rpm is no load - there isn't much resistance compared to when it is working, and the rpms are much higher than when it is working. Does it include a chain going around a bar? How does total bearing friction compare to a chain in the wood? What exactly does a 500rpm no load increase in rpm translate to under load?

Still, the saw already runs really well.


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## Derf (Mar 16, 2016)

Chris-PA said:


> From their ad:
> 
> _*Overall friction is more than 10% less than an all-steel bearing of the highest quality. We've seen an increase in 500 free rpm on a Husky 357. This translates into speed in the wood, under load.*_
> 
> ...



Good points all around. The ceramic ball bearings will be harder than steel, with a lower frictional surface so their "rolling resistance" is lower. 

Do you have any experience on a bicycle? Think of this as the difference between pedaling on flat ground with a knobby tire vs a smooth tire, or a fatter tire vs a skinnier tire. 

The second upshot is that provided the bearings are kept clean, they should last longer than steel bearings. Just theory though, not much evidence yet showing service intervals. 

As to how it affects real world use with a bar and chain load, or when cutting wood, if you are making a cant racer it might help you earn 0.1 second faster cuts. Back to the bicycle analogy - if you are biking up hill towing a trailer behind you, you'll probably forget or can barely tell if you have a knobby or smooth tire.

They are claiming "more than 10% reduction in friction". That might translate to a significant reduction in drive train losses when there is no load, which might work out to 500rpm. But when there is a chain to drag around a bar, or through wood, there is a lot more friction to overcome. Suddenly the reduction of "more than 10%" in the bearing ends up as .05% of the total frictional load. 

Are ceramic bearings better than top steel bearings? Probably. Are they worth their price? Debatable. Would I go out and swap my bearings and expect any noticeable improvements? No.


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## smokey7 (Mar 16, 2016)

I am very interested in this. I really want to know the details and limitations from using these bearings and forged pistons. I would have to bet that the piston must be undersized to give room for expansion. I would love to learn more about this and what the real measurements are. Piston to cyl clearance, crown to pin height, ring pin location, any any other info.


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## Marshy (Mar 16, 2016)

smokey7 said:


> I am very interested in this. I really want to know the details and limitations from using these bearings and forged pistons. I would have to bet that the piston must be undersized to give room for expansion. I would love to learn more about this and what the real measurements are. Piston to cyl clearance, crown to pin height, ring pin location, any any other info.


These specific bearing are rated ABEC-5 for extreme running accuracy. The manufacturing tolerances of the races and rolling elements are more strict when compared to lesser ABEC-1 rated bearings that you buy on eBay or from your dealer. What that means is they have higher running accuracy and a higher speed rating as well.

http://www.skf.com/us/products/mrc/precision-abec-5-and-abec-7-bearings/index.html


The silicon nitride hybrid bearing was created primarily as a way to isolate rotating equipment that have the potential to conduct electricity. Things like armatures in motors and generators or shafts. Traditional steel bearings have the potential to conduct electricity and cause damage to the race surface and breakdown of the lubricant. The silicon nitride acts as an electrical insulator. The hybrids also have longer service life, generate less running heat and can sustain operation with a thinner lubricant film. They are more tolerant to solid particle foreign material contaminants and the list goes on...

http://www.skf.com/us/products/mrc/hybrid-ceramic-ball-bearings/index.html


Regarding the forged piston... Their web site says less expansion due to increased silicon but what they didn't say was if that is compared to other forged pistons or cast pistons. In general, forged pistons expand more than cast so there's not enough info provided IMO.

I have first hand experience with Wiseco ****ing up their piston redesign and miss judging the expansion of their pistons. It took about 5 people and a dozen pistons and and equal number of damaged cylinders to convince them it was something they did and not us. It took nearly a year and a half to resolve it and we all were out the cost of our wrecked cylinders. They claimed to of found the issues and corrected it and comp'ed us new corrected pistons... Feel like taking a guess if I've used them since?


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## blsnelling (Mar 16, 2016)

Here it is with an additional .035" popup and a proper tune. It still 4-strokes when pulled out of the cut even with it tuned to 14,900. That's very surprising without any porting!


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## stihlaficionado (Mar 16, 2016)

blsnelling said:


> Here it is with an additional .035" popup and a proper tune. It still 4-strokes when pulled out of the cut even with it tuned to 14,900. That's very surprising without any porting!





Almost as fast as my 261


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## Marshy (Mar 16, 2016)

stihlaficionado said:


> Almost as fast as my 261 headed into the garbage


Fixed


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## stihlaficionado (Mar 16, 2016)

Marshy said:


> Fixed


Now why would I want to get rid of that beast?

Nice saw Brad. Me like Red & Black


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## Chris-PA (Mar 16, 2016)

blsnelling said:


> Here it is with an additional .035" popup and a proper tune. It still 4-strokes when pulled out of the cut even with it tuned to 14,900. That's very surprising without any porting!
> 
> rpm



Around 0:30 it's turning about 11k, and around 1:30 it's turning 12,780rpm. Kinda scooting right along.


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## CR888 (Mar 16, 2016)

I have always liked Wiseco pistons and ran them in dirt bikes. Does anyone know the difference in wieght between the OEM 372xp piston and the Wiseco? My only concern in a chainsaw application would be that their may be good reason the oem's use light pistons in chainsaws. Modern saw design favours a wide bore short stroke high rpm design. A piston changing direction 10-15000 times a minute maybe does not benefit from a heavy piston as it may reduce power. They sure do look nice though with the muffler removed with the 'Dominant' logo on display. I wonder how well they dissapate heat in comparison to OEM. All I am 'suggesting' is there maybe good reason Wiseco has no contracts supplying pistons to the OhPeEe industry (if I write O P E it gets censored, funny that on a site discussing O*P*E).


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## blsnelling (Mar 16, 2016)

These are lighter than the OEM piston by about 7 gram.


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## blsnelling (Mar 16, 2016)

Chris-PA said:


> Around 0:30 it's turning about 11k, and around 1:30 it's turning 12,780rpm. Kinda scooting right along.


I didn't have my tach on it in the cut, but I figured it was up there pretty good.


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## blsnelling (Mar 16, 2016)

Marshy said:


> The silicon nitride hybrid bearing was created primarily as a way to isolate rotating equipment that have the potential to conduct electricity.
> http://www.skf.com/us/products/mrc/hybrid-ceramic-ball-bearings/index.html
> 
> Regarding the forged piston... Their web site says less expansion due to increased silicon but what they didn't say was if that is compared to other forged pistons or cast pistons. In general, forged pistons expand more than cast so there's not enough info provided IMO.
> ...


I've always understood forged pistons to expand more than cast pistons as well. That's why you have to size the bore a little larger for a forged piston, otherwise they'll scuff and/or seize. 

I also noticed they mentioned "hypueretic" as well. I thought that was a higher quality cast piston, kind of the strength of forged without the expansion concerns.

Were you referring to the Wiseco pistons from Baileys? I had multiple issues with those myself. I ended up pitching them in the recycle bin. Those obviously weren't speced right. I'm not going to pin that completely on Wiseco.


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## Marshy (Mar 17, 2016)

blsnelling said:


> I've always understood forged pistons to expand more than cast pistons as well. That's why you have to size the bore a little larger for a forged piston, otherwise they'll scuff and/or seize.
> 
> I also noticed they mentioned "hypueretic" as well. I thought that was a higher quality cast piston, kind of the strength of forged without the expansion concerns.
> 
> Were you referring to the Wiseco pistons from Baileys? I had multiple issues with those myself. I ended up pitching them in the recycle bin. Those obviously weren't speced right. I'm not going to pin that completely on Wiseco.



Your regular cast piston is considered a eutectic piston. The hypereutectic pistons are also cast pistons but "hyper" (over) eutectic is a terminology that describes the metallurgic composition of the aluminum alloy on a molecular level.

Its kind of like mixing sugar in water in the fact that the water can become saturated with sugar to the point it wont dissolve any more sugar and any additional will remain granular at the bottom of the glass as a separate form, non homogeneous. Hypereutectic is used to define the percentage of silicon (primarily) in the alloy. The advantage of hypereutectic is light weight and low expansion but the disadvantage is they are brittle and don't take well to detonation.

Regarding strength, forged materials take the cake. The disadvantage to forged pistons is they have a higher density and internal stress so they expand more.

My negative experience with Wiseco was with snowmobile engines. It would have been a lot cheaper if it was with chainsaws. Unfortunately they were the only ones making a piston for that motor at the time so our hands were tied. It wasn't until later we learned the OEM had another piston in a new sled that was plug and play.


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## blsnelling (Mar 17, 2016)

That confirms what I thought, meaning that the following sentence is a contradiction of terms, correct?

"The *hypereutectic forged *pistons, are lighter, have *lower thermal expansion*, are better balanced, and boost compression by 20psi."


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## Marshy (Mar 17, 2016)

blsnelling said:


> That confirms what I thought, meaning that the following sentence is a contradiction of terms, correct?
> 
> "The *hypereutectic forged *pistons, are lighter, have *lower thermal expansion*, are better balanced, and boost compression by 20psi."


That statement is incorrect.


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## grizz55chev (Mar 17, 2016)

My old Chevy with the Vortec 5.7 v-8 has these hyperutectic pistons and now has 295,000 miles, still uses no oil on original engine, never been apart.


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## Marshy (Mar 17, 2016)

grizz55chev said:


> My old Chevy with the Vortec 5.7 v-8 has these hyperutectic pistons and now has 295,000 miles, still uses no oil on original engine, never been apart.


GM really improved the ring package they put on those pistons and made improvements in the metal of the cylinders. They just don't wear like the old ones did.


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## bwalker (Mar 17, 2016)

I have ran many Wiseco pistons over the years with good luck. I always set them up on the generous side clearance wise.

I will say that their single ring GP pistons when used in mx bikes last significantly less long than their dual ring pro-life counter parts.


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## Cantdog (Mar 17, 2016)

Marshy said:


> GM really improved the ring package they put on those pistons and made improvements in the metal of the cylinders. They just don't wear like the old ones did.



The entire engine was improved......modernized......clearances tightened...not your dads Cheby........I runs a 4.3 6 cyl MPI fuel injected Vortec in my off shore boat......42 mph by GPS.......not a fast hull.....65 lbs oil pressure @ 3000 rpm..hot....liking it.....


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## Marshy (Mar 17, 2016)

Cantdog said:


> The entire engine was improved......modernized......clearances tightened...not your dads Cheby........I runs a 4.3 6 cyl MPI fuel injected Vortec in my off shore boat......42 mph by GPS.......not a fast hull.....65 lbs oil pressure @ 3000 rpm..hot....liking it.....



I just personally built my own 5.7L Vortec for my '84 K10 pickup and so far it's been a good motor. The short block was a junkyard motor and was in great shape. It has fantastic oil pressure. I had to ask my machinist if 60 psi was abnormal lol.


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## SCHallenger (Mar 19, 2016)

grizz55chev said:


> My old Chevy with the Vortec 5.7 v-8 has these hyperutectic pistons and now has 295,000 miles, still uses no oil on original engine, never been apart.



Interesting! I have an '02 Suburban with the 5300 series Vortec & has 347,000 mi & has never burned a drop of oil. My previous one was a 5.7L which was a 350cu in. but not a Vortec. The 5300 series is about 325cu in., I believe. I thought that the next size up from the 5300 was a 6000 which should be around 400cu in.? Anyway, that many miles with that kind of performance is very impressive. If some of the reason for that is eutectic pistons, it sure speaks well for them! Oh yeah, mine has pulled a small horse trailer through some tough terrain (mountains of W.Va., Va., Tenn., & NC.) for 50,000 of those miles!


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## grizz55chev (Mar 19, 2016)

I think the Vortec comes with roller lifters as well, never changed the timing chain or gears, only the fuel injectors, ( 3 times ) and fuel pump, ( 4 times ).


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## Marshy (Mar 20, 2016)

grizz55chev said:


> I think the Vortec comes with roller lifters as well, never changed the timing chain or gears, only the fuel injectors, ( 3 times ) and fuel pump, ( 4 times ).


Yes, roller cam/lifters and fuel injection.


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## blsnelling (Mar 22, 2016)

I don't normally work on saws on week nights, but was anxious to see this 2171 ported. So, I tackled the job last night and finished it up this evening. WOW!!!! I do believe this is the strongest 70cc class saw I've ever built. This thing is just insane! It make ridiculous RPMs and pulls like a mule. I love it! I think I have a new favorite saw


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## Chris-PA (Mar 22, 2016)

Wow. Now what part of that do you attribute to the piston and bearings? Skeptical as I was about how those pieces would contribute, it's really hauling ass so it's hard to argue.


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## blsnelling (Mar 22, 2016)

Here's my typical 372XP. I still have this saw. I'll have to do a video with the same B&C. I'd say it's very comparable, but I think this new one may have an edge. If nothing else, I'm not used to running my 372s with a 20" bar.


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## silveradol9h (Mar 22, 2016)

blsnelling said:


> I don't normally work on saws on week nights, but was anxious to see this 2171 ported. So, I tackled the job last night and finished it up this evening. WOW!!!! I do believe this is the strongest 70cc class saw I've ever built. This thing is just insane! It make ridiculous RPMs and pulls like a mule. I love it! I think I have a new favorite saw



That thing is screaming. Sounds amazing too.

Sent from my SM-G920V using Tapatalk


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## Jacob J. (Mar 22, 2016)

Looks and sounds good Brad- I like how it's self-feeding through the wood at that RPM.


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## Termite (Mar 23, 2016)

Marshy said:


> GM really improved the ring package they put on those pistons and made improvements in the metal of the cylinders. They just don't wear like the old ones did.


Olds did the same thing but in the nineteen sixties.


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## blsnelling (Mar 28, 2016)

I got to put a couple tanks through this saw Saturday. It ran fantastic with no issues at all. Compression is now about 192 PSI. The saw is wearing a 28" B&C with full comp Stihl RS chain. The wood is Shag Bark Hickory. I apologize for the poor video quality. It came from a friends cell phone.


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## blsnelling (Mar 28, 2016)

The new 1/2 wrap handle and filter cover came today.


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## LowVolt (Mar 28, 2016)

Boooooooo...


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## blsnelling (Mar 28, 2016)

LowVolt said:


> Boooooooo...


You had your chance!


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## LowVolt (Mar 28, 2016)

No booooo to the half wrap.

Please. If I would have built it, It would still be in my basement disassembled.


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## LowVolt (Mar 28, 2016)

Me after I disassemble a saw down to the crank......


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## blsnelling (Mar 28, 2016)

LowVolt said:


> No booooo to the half wrap.
> 
> Please. If I would have built it, It would still be in my basement disassembled.


I have no use for a full wrap handle. They only get in my way.


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## blsnelling (Mar 28, 2016)

LowVolt said:


> Me after I disassemble a saw down to the crank......
> 
> View attachment 494927


We can fix that


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## blsnelling (Apr 13, 2016)

Here's the final product. 24" T&L bar.


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## CR888 (Apr 13, 2016)

Nice lawn there too Brad!


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## Big_Wood (Apr 14, 2016)

CR888 said:


> Nice lawn there too Brad!



that's not really a lawn. it's a hydroponic astro turf pad in his basement. he spends alot of time caring for it so he can take some beauty saw photo's. he told me he ported the hydroponic system and it's been out of control. this is why you see brad posting pics of saws in nice lush grass in the middle of winter


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## Chris-PA (Apr 14, 2016)

Grass is a lousy crop. Now dandelions are some good eating!


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## J. Talley (Apr 14, 2016)

I've always thought it would be interesting to have a yard of goat heads. I'd never have to worry about the dogs running away!


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## mdavlee (Sep 12, 2016)

blsnelling said:


> I don't normally work on saws on week nights, but was anxious to see this 2171 ported. So, I tackled the job last night and finished it up this evening. WOW!!!! I do believe this is the strongest 70cc class saw I've ever built. This thing is just insane! It make ridiculous RPMs and pulls like a mule. I love it! I think I have a new favorite saw



So is this piston worth it? I'm going to build myself a 372/2171 and was eyeballing these pistons again.


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## blsnelling (Sep 12, 2016)

If you can do your own machine work, I don't see where they buy you much more than any other piston.


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## mdavlee (Sep 12, 2016)

blsnelling said:


> If you can do your own machine work, I don't see where they buy you much more than any other piston.


Ok. A meteor is $30 so you get 3 for the price of that one. I was just wondering how much weight savings over a meteor it gives. Anything to help the bottom end live longer.


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## blsnelling (Sep 12, 2016)

I don't recall if I weighed it or not. I believe he's selling gen II which is lighter than the one I had.


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## mdavlee (Sep 12, 2016)

I figure it's probably 10 grams or more lighter than a meteor. They're always heavier than what they replace from what I've seen


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## Deleted member 150358 (Jan 14, 2018)

Anyone ran the V3 piston?
Sounds like it may more of a finished product. More dome, something changed intake timing. 

Wonder if the 52mm Stihl MS-460 piston will work in a 52mm xpw cylinder? Sposedly was coming in December.


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## Eric howes (Mar 24, 2018)

Any update on this piston? How is it holding up


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## cgraham1 (Mar 24, 2018)

Eric howes said:


> Any update on this piston? How is it holding up


I’ve ran several tanks through my 2171 that @mdavlee ported, and have had zero issues. It is very strong for a 71cc saw.


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## Eric howes (Mar 25, 2018)

I find this very interesting. I wish the made the 52mm version of this piston


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## wildman ben (Apr 4, 2018)

Yea I'm curious also how snellings saw or anyone else whose used this piston has held up. There is an article on the dominant site about the titanium wrist pin not lasting, so probably not a good option for a work saw. And also heard the rings on the piston don't last? How has yours held up, as well as the bearings. Is it worth installing these parts over say a husky 268 pop up piston in a 372 or is this dominant piston the best answer?

Sent from my SM-G900W8 using Tapatalk


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## Little Al (Apr 4, 2018)

Rx7man said:


> I figured it would be expensive.. but I will say it looks very nicely finished.. you get what you pay for.
> 
> Back in my Rx7 days, I put about $10,000 into an engine, best of everything went into it, additional dowel pins, apex seals that cost $200 each (x6), and lots and lots of porting... I didn't own it long enough to push it to it's limits by far.. but it made 375 RWHP at just 11 PSI of boost... and a buddy of mine with a very similar engine did push his to the limits.. he got 875 RWHP at 48 PSI on race gas from 1.3L.. he also daily drove it (at about 500 rwhp pump gas) and it lived for about 50,000 miles.. The castings gave out and cracked at that point.
> 
> Power, Reliablility, Cost. Pick 2!


I doubt you can get the best of the first 2 without the 3rd


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## cgraham1 (Apr 4, 2018)

wildman ben said:


> Yea I'm curious also how snellings saw or anyone else whose used this piston has held up. There is an article on the dominant site about the titanium wrist pin not lasting, so probably not a good option for a work saw. And also heard the rings on the piston don't last? How has yours held up, as well as the bearings. Is it worth installing these parts over say a husky 268 pop up piston in a 372 or is this dominant piston the best answer?


I’ve got at least ten tanks through mine and everything seems fine... 

Mine has the stock wrist pin and bearings. It was in such good shape, it seemed like a waste to replace the bearings.


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## wildman ben (Apr 4, 2018)

cgraham1 said:


> I’ve got at least ten tanks through mine and everything seems fine...
> 
> Mine has the stock wrist pin and bearings. It was in such good shape, it seemed like a waste to replace the bearings.


Is the cylinder ported or any other mods or just the piston? And how does it compare


Sent from my SM-G900W8 using Tapatalk


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## Eric howes (Apr 4, 2018)

wildman ben said:


> Is the cylinder ported or any other mods or just the piston? And how does it compare
> 
> 
> Sent from my SM-G900W8 using Tapatalk


Read to entire post he talks about what he did. He tried it as just the piston and then ported it, there is actually videos of each


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## a. palmer jr. (Apr 4, 2018)

After waiting a few weeks I've decided that my next piston will come from a vendor in the United States...


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## cgraham1 (Apr 4, 2018)

wildman ben said:


> Is the cylinder ported or any other mods or just the piston? And how does it compare.





Eric howes said:


> Read the entire post he talks about what he did. He tried it as just the piston and then ported it, there is actually videos of each.


@mdavlee did the port work and installed the cylinder.


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## Rx7man (Apr 5, 2018)

Little Al said:


> I doubt you can get the best of the first 2 without the 3rd


I should have said "Cheap"...pick two


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## SquareFile (Apr 5, 2018)

Eric howes said:


> I find this very interesting. I wish the made the 52mm version of this piston



Wiseco 48, 50, 51.4, and 52mm are being made for @Definitive Dave . IMO a much better design than dominant, especially for the performance enthusiast.


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## Definitive Dave (Apr 5, 2018)

I do love a shameless plug 

About 2 years in the design phase of this model, bouncing around in the heads of smart chainsaw gurus. After some bizarre manufacturing glitches and a lot of weeping and pleading we are really happy with these. 

All pistons 1mm single ring, centered on intake, lightened, with coatings to ring land
346xp ne 44.3mm pop-up - one on hold for Adirondackstihl raffle, sold out
346xp ne 44.3mm flat top race - one on hold for Adirondackstihl raffle, sold out
MS661 pop-up 56mm - ring incompatible with Stihl plating, three in stock, new rings in the works from Total Seal
MS66o pop-up 54mm pop-up - windowless, ring incompatible with Stihl plating, sold out
MS660 pop-up 56mm big bore - windowless, ring incompatible with Stihl plating, sold out
365 Special 48mm race, one on hold for customer, sold out
372xp 50mm race, three in stock
372xpw 51.4mm race, one in stock
372 big bore 52mm race, sold out
3140 husqvarna 62mm big bore, more than 5 in stock

A bunch of smart builders grabbed some up this past weekend at the Hedgefest races and we had all 10 models on hand for fondling and show and tell 
I am planning to take the ten samples and a a few of the pieces we still have in stock to Michigan for EJs GTG this weekend and any of the other GTGs i can attend this year.

We have a lot of other models in the works already, we try to get a lot of input from racers and builders ahead of time and put the product in the hand of real saw men to torture test and try to destroy in the woods before offering any for sale.

Upcoming:
60mm windowed 1mm and 1.2mm single ring race and pop up versions for 084/088/ms880/3120
181 full circle skirt thin ring race
281 full circle single ring 1.2mm race and pop up
288 full circle single 1mm ring race and 1.2mm pop up 
MS661 race and pop up versions 1.2mm ring
MS660 54 and 56mm race and pop up 1.2mm single ring
346xp ne and oe race and pop up 1mm single ring
Race and pop up versions for 7900, 2100, 044, 046, ms461, 056 mag2, 166


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## Little Al (Apr 5, 2018)

Some years back I was searching sources for a piston for an obscure Italian saw I found one on Ebay It when it came it was a Garelli It's the best made piston I've ever come across some time later I tried to contact the address on the box but never received a reply maybe taken over /gone out of business Shame it was a quality bit of kit I know that a company of the same name produced Mopeds & small capacity moto bikes but think this was a different company with the same name Any one else heard/come across them?


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## Marshy (Apr 5, 2018)

Definitive Dave said:


> ...
> 
> 372xp 50mm race, three in stock
> 372xpw 51.4mm race, one in stock
> ...


Dave, I have a few questions for you. What are the price of the 372 50mm pistons, is it on your site? 

Do you know what the 2100 piston will cost yet?

What do you think about using any of the 372 pistons in a work saw?


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## SierraMtns (Apr 5, 2018)

Marshy said:


> Dave, I have a few questions for you. What are the price of the 372 50mm pistons, is it on your site?
> 
> Do you know what the 2100 piston will cost yet?
> 
> What do you think about using any of the 372 pistons in a work saw?



I would like to know how it runs in a work saw.


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## SierraMtns (Apr 5, 2018)

Definitive Dave said:


> I do love a shameless plug
> 
> About 2 years in the design phase of this model, bouncing around in the heads of smart chainsaw gurus. After some bizarre manufacturing glitches and a lot of weeping and pleading we are really happy with these.
> 
> ...




Do you have any videos with the saws running?


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## Definitive Dave (Apr 5, 2018)

Marshy said:


> Dave, I have a few questions for you. What are the price of the 372 50mm pistons, is it on your site?
> 
> Do you know what the 2100 piston will cost yet?
> 
> What do you think about using any of the 372 pistons in a work saw?


The 372 models are specifically for racing, there will be pop-up performance models as well but the race pistons are all flat tops.
The only work saw pistons out there are in some of the 346xps, i will look for some footage. 
Most of the pistons will be $125-150 shipped , they willl be added to to the website soon.
Thanks
Dave


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## Rx7man (Apr 5, 2018)

This is making me drool!


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## Marshy (Apr 6, 2018)

Definitive Dave said:


> The 372 models are specifically for racing, there will be pop-up performance models as well but the race pistons are all flat tops.
> The only work saw pistons out there are in some of the 346xps, i will look for some footage.
> Most of the pistons will be $125-150 shipped , they willl be added to to the website soon.
> Thanks
> Dave


Thanks for explaining. I'm surprised that the race saw pistons are flat top and the non-race pistons are pop-ups. I'd be tempted to run the flat top in a ported work saw.

Maybe I'm missing something... are the race pistons manufactured with an extra large compression height so they have to be machined to spec by builder before they can be used? Or are they drop in ready to use?

Sorry for asking so many questions, I'm just trying to understand the product. If this is already explained on your site then let me know, I won't ask you to reiterate.


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## mgr (Apr 6, 2018)

Any pics of the 166 race piston?


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## SquareFile (Apr 6, 2018)

Marshy said:


> Thanks for explaining. I'm surprised that the race saw pistons are flat top and the non-race pistons are pop-ups. I'd be tempted to run the flat top in a ported work saw.
> 
> Maybe I'm missing something... are the race pistons manufactured with an extra large compression height so they have to be machined to spec by builder before they can be used? Or are they drop in ready to use?
> 
> Sorry for asking so many questions, I'm just trying to understand the product. If this is already explained on your site then let me know, I won't ask you to reiterate.


The pistons can be used for any purpose. The popups are for drop in compression increase. I think Dave is using "race" as slang. They are flat because compression can be increased with two piece or squish cut. Just two options will have available.

I've been using 346 popup in a stock cylinder with no issues.


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## Definitive Dave (Apr 6, 2018)

Shawn is say me word better than i do  Thank you sir.

I think of the flat tops as race pistons because compression in race saws can be raised in several ways as @SquareFile mentioned, many of mine have two piece heads and other tomfoolery.

Only the 10 models at the top have been produced, it a slow process, you can assume the 166 race pistons will be awesome, in about a year 
Dave


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## wildman ben (Apr 8, 2018)

OK so they can be used in worksaws if the builder knows what he's doing and adjusts the cylinder instead? (For the flat top 372 pistons)In that case what is the website that I can buy these from?

Sent from my SM-G900W8 using Tapatalk


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## SierraMtns (Apr 10, 2018)

SquareFile said:


> The pistons can be used for any purpose. The popups are for drop in compression increase. I think Dave is using "race" as slang. They are flat because compression can be increased with two piece or squish cut. Just two options will have available.
> 
> I've been using 346 popup in a stock cylinder with no issues.



This would be sweet if the 372 piston could be used in a stock saw. Guys can port them and then still run a base gasket with this piston and have a crazy strong saw....hmmm


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## Eric howes (Apr 10, 2018)

SierraMtns said:


> This would be sweet if the 372 piston could be used in a stock saw. Guys can port them and then still run a base gasket with this piston and have a crazy strong saw....hmmm


Yes that would be awesome if they came out with a drop in pop up piston for a stock saw


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## Mike Gott (Apr 10, 2018)

Definitive Dave said:


> I do love a shameless plug
> 
> About 2 years in the design phase of this model, bouncing around in the heads of smart chainsaw gurus. After some bizarre manufacturing glitches and a lot of weeping and pleading we are really happy with these.
> 
> ...


Any 390 ones in the pipeline?


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## Mike Gott (Apr 10, 2018)

Eric howes said:


> Any update on this piston? How is it holding up


I got one in my 2171 that Eric ported for me, I probably got 40-50 tanks of fuel through it. It’s runs really well!!


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## trappermike (Apr 14, 2018)

How much does that piston weigh compared to a stocker?


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## zorak (Aug 9, 2020)

blsnelling said:


> I have run ceramic bearings in a couple other saws with good results. It's critical to use those with black Si3n4 balls, not the white ZrO2 balls. The ZrO2 balls will fail within a tank or two. I have run hybrid ceramic bearings with Si3n4 balls for several years in a high RPM 346XP with no issues at all. I also have them in my piped 390XP.


Why ceramic or steel crank bearings?


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## dustinwilt68 (Aug 9, 2020)

Ceramic has less friction, smoother. Cost is way higher though. OEM bearing is 10.00 average, ceramic is closer 50-60 each.


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## MustangMike (Aug 10, 2020)

Ceramic is harder, and can produce less friction, but it is also more brittle. Also, some of the advantage is lost due to the fact that the race is steel and not as hard as the bearing.


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## president (Aug 10, 2020)

Rx7man said:


> Nice looking stuff!.. cost?


Hijack Alert! Don Glascko needs you to sell him a saw.


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## Huskvarna hotellgäst (Aug 10, 2020)

I can't see there'd be much advantage in ceramic bearings in a high rpm unsealed (i.e. constantly washed in fuel/air mix) application.


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## jp233 (Aug 11, 2020)

they've been used as part of the secret to big power in 2-stroke racing machines (such as 125GP and 250GP racebikes, this I know for certain) - they can be MUCH lighter (like 50-60%), plus less friction.

Power costs money!


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## Huskvarna hotellgäst (Aug 11, 2020)

jp233 said:


> they've been used as part of the secret to big power in 2-stroke racing machines (such as 125GP and 250GP racebikes, this I know for certain) - they can be MUCH lighter (like 50-60%), plus less friction.
> 
> Power costs money!


Ah! lighter weight. I'd not considered that in a small engine application.


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## Marshy (Aug 19, 2020)

The primary use of ceramic hybrid bearings (ceramic balls with steel races) are in electric motors. The ceramic is an insulator and eliminates stray voltage passing through the bearing and damaging it. An advantage is they can withstand continued operation in the absents of lubricant. The ceramic balls will not micro weld to the race and damage it. Otherwise they have a comparable rated life and load capacity as of steel bearings but slightly less rolling resistance.


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