# Removing base gasket question.



## A.E. Metal Werx (Nov 2, 2008)

hey guys i had a topic about geting more power out of my 372 and my 346. i have seen lots about removing the base gaskit for a cheap easy way for more power. so i plan to do that but was wondering if you just take the gaskit it out and thats it or do you need to use a type of liquid gaskit to compensate for existing gaskit? thanks


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## MS460WOODCHUCK (Nov 2, 2008)

mx_racer428 said:


> hey guys i had a topic about geting more power out of my 372 and my 346. i have seen lots about removing the base gaskit for a cheap easy way for more power. so i plan to do that but was wondering if you just take the gaskit it out and thats it or do you need to use a type of liquid gaskit to compensate for existing gaskit? thanks



Good question, I'm watching for the answers to because I don't know. Was wondering if it will work on all saws.:monkey:


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## chainsawwhisperer (Nov 2, 2008)

There's more to it than removing the base gasket. I'll post the details tomorrow. CSW


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## A.E. Metal Werx (Nov 2, 2008)

chainsawwhisperer said:


> There's more to it than removing the base gasket. I'll post the details tomorrow. CSW



thanks CSW, looking fwr to it!


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## chainsawwhisperer (Nov 3, 2008)

Ok, first off just removing the base gasket is not a free horsepower fix.
I see that the 372 is muffler modded, that's a good start.
Removing the base gasket does 3 things, 1. increases compression, 2. decreases squish volume, 3. changes port timing.
First thing to do is measure your squish, and see if there is room to drop your cyl. For a work saw I think that you want to keep .020 clearance.
Search for thread - "Getting all squishy inside"

By lowering the cyl. the port timing is altered (I'm thinking it retards port timing) By retarding the port timing the saw most likely will lose some top end power. To overcome this and get the port timing back to where it was before,
the top of the piston is machined around the edges, to remove the same thickness as the original gasket. Search (Pop-up piston)

I saw that you are aware that fuel requirements - octane and mixture F/A will change as well. 
How big is the wood that you usually cut? can you go with a shorter bar? that will free up HP.
I'm not tying to be a nay-sayer, but you need to be aware of all that goes into it. 
Done properly along with mild porting you will see very good gains.

Search for all the info that you can on doing this. 

There are a lot of people on this site with much more experience than myself. So I know I probably left some things out. 

Good luck and keep us posted!
CSW


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## davefr (Nov 3, 2008)

I believe you can also reduce the intake port by the amount that you reduce squish. However the best way is to use a timing wheel and take detailed readings.

Some members have indicated that reducing squish barely alters timing so don't worry about it. Just enjoy the extra compression and keep it simple.

You really need to know your starting point for a specific saw and can't assume stock saws all have the same factory squish due to manufacturing variances. The best method that I've used was to remove the piston rings and place two small pieces of solder on the piston at the intake and exhaust side to minimize any rocking. (a dab of grrease works well to keep the solder in place.) Now torque down the cylinder and rotate the crankshaft a few times. Remove the cylinder and measure both flattened pieces of solder with a micrometer and average out the readings. That's your starting point. There are many methods to reach that sweet spot of .020". (ex: gasketless, beer can, paper bag, gasket compound only, etc)


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## funky sawman (Nov 3, 2008)

On my 372 I removed the base gasket and raised the exhaust port .018. Then I triple ported the muffler and added a double stack air filter. The saw runs awsome and It idle's well too. I tested it and it cuts with a 385 husky until wood gets bigger than 36".


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## Tree Sling'r (Nov 3, 2008)

You will be fine removing the base gasket with your timing, it will not effect it that much.
You will need a sealant though. Got to your local bike shop and get some Yamabond, or Honda bond. I use Dirko, but it is hard to find.
Most 372's are .036 stock squish. The base gasket is .017, so you are looking at .019 which is a safe squish for a 372.
I would though recommend checking squish, and learning about the port timing methods for compensation of removing the base gasket although, in this case it is not a real biggie.
Beaware, the mods you are wanting to perform on this saw may be retarded by a limited ignition module, depending on what year the saw is.
If the ignition is blue, your limited.

The points in previous post very valid, but not as nessecary as some may beleive in this case.


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## A.E. Metal Werx (Nov 3, 2008)

i do have a limited coil. what is a safe rpm that the 372-346 can run befor it starts geting hard on things?


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## A.E. Metal Werx (Nov 3, 2008)

also. i have always used gaskit sealer-glue made by locktight. it is brown in color if that helps any one. i would think that this stuff should work great but if others think different please let me know.


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## Tzed250 (Nov 3, 2008)

.


Dirko, Yamabond, Hondabond, Threebond.


.


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## Tree Sling'r (Nov 3, 2008)

mx_racer428 said:


> i do have a limited coil. what is a safe rpm that the 372-346 can run befor it starts geting hard on things?



Your gonna have to aquire an ear. Every saw is different, due to what mods have been made. I only use a tach as a reference. I demo most of my ported and milled saws for other fallers so I give them a reference from the tach to tune it by.
Other than that it is all ear.
If you don't know what your doing, your next thread may be: "Where can I get a new P&C for my 372."


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## chainsawwhisperer (Nov 3, 2008)

Tree Sling'r said:


> If you don't know what your doing, your next thread may be: "Where can I get a new P&C for my 372."



ROFL


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## chainsawwhisperer (Nov 3, 2008)

Here is a good read on this subject.

http://www.arboristsite.com/showthread.php?t=79507


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## A.E. Metal Werx (Nov 3, 2008)

so from what i gather. if you take the gaskit out you will loose a little rpm on top.. how much are we speaking of? insted of running 13600 it will run what 13000? and by loosing some top end but geting some low. couldnt a guy just put a 8pin sprocket on?


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## Stihl051master (Nov 3, 2008)

I've used the threebond 1104 sealant on a lot of different things, and IMO it would be the best to use if you remove the base gasket. It's made to to seal 2 piece engine cases such as on a dirt bike or snowmobile. The stuff works really well, and will put a good seal on any gasket that you may have leaking problems with. I bet the Hondabond etc. are about the same stuff. A couple words of caution - it is a huge pain in the a$$ to get off (your skin included) so only apply it when you want something sealed up and plan to leave it that way. Also they changed the number from 1104 to something else with a bit different formula, because the original 1104 has lead in it! :jawdrop: I want to say it's now 1105 or 1114or something, I have a tube in the shop, but I don't feel like walking out there right now.


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## Tree Sling'r (Nov 3, 2008)

mx_racer428 said:


> so from what i gather. if you take the gaskit out you will loose a little rpm on top.. how much are we speaking of? insted of running 13600 it will run what 13000? and by loosing some top end but geting some low. couldnt a guy just put a 8pin sprocket on?



Dude...Your giving me a headache. 

Warm your saw up, make a few cuts after properly tuned. Make notes, video or whatever.
Pull the gasket, seal the jug run the saw, make notes, video or whatever.
Do both with a 7 and a 8 tooth sprocket.
Whatever your gonna do, you have to experiment when you want gains.
I can attest that gains are not free. I have spent 1000s of dollars on trial and error before I got a grasp of what worked.
Read and re-read, do searches, look at pictures watch other videos. The information is here, but YOU have to experiment.
I am more than happy to lend any advice, but ya gotta get off the pot.


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## Crofter (Nov 4, 2008)

*Full throttle, no load, rpm* is as little a prediction of a saws performance as freckles! I get a kick out of seeing this figure bragged up! It is only what RPM the saw holds in the cut that counts for anything. There are more than a few so called "screamers" around that fall on their faces when put to the wood unless some special effects go into the chain or the cutting technique. 

Depending on the porting of the *particular* saw you are talking about, it (removing gasket without readjustment of exhaust port height) might make a little more or a little less difference in the charted HP and torque curves. There could be some subtle differences but not for a work saw.

I agree with Tree Slingr here; if it is a race saw you want to build, you got some reading to do and likely a few cylinders to screw up in the process!


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## blsnelling (Nov 4, 2008)

I use 1104 to seal up a lot of things. When working on the old saws, I often reuse the old gasket and just reseal with 1104. That way everything's still the same thickness.

If you loose any RPMs by taking the base gasket out, it will be negligible. It's only going to retard your exhaust timing by 1*, but the intake timing will be advance 1*. If you've got the squish room, just do it.


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## Nailgunner (Nov 4, 2008)

Another plug for Loctite 574. Datasheet here: http://65.213.72.112/tds5/docs/574-EN.pdf


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## Tzed250 (Nov 4, 2008)

Nailgunner said:


> Another plug for Loctite 574. Datasheet here: http://65.213.72.112/tds5/docs/574-EN.pdf



I don't believe that is easily available in the US.


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## funky sawman (Nov 5, 2008)

Here is somthing interresting on this matter. The Dolmar 5100"s that I've seen blowen up have two different head gaskets but still have the same exact cylinder head casting. ON most of the 5100's they install a .018 thick gasket, BUT I have seen many, even newer serial # saws have a .036" thick head gasket!!!!!! Dolmar tells me that it dosn't make that much difference in timing so dont worry about it!!!:jawdrop:


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## blsnelling (Nov 5, 2008)

funky sawman said:


> Here is somthing interresting on this matter. The Dolmar 5100"s that I've seen blowen up have two different head gaskets but still have the same exact cylinder head casting. ON most of the 5100's they install a .018 thick gasket, BUT I have seen many, even newer serial # saws have a .036" thick head gasket!!!!!! Dolmar tells me that it dosn't make that much difference in timing so dont worry about it!!!:jawdrop:



It would only affect the timing about 1*. I'd be more concerned about the compression loss.


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## timberwolf (Nov 5, 2008)

A 0.5mm change to exhaust port height on a 36mm stroke is about 3.4 deg total durration, that is not insignificant. You do raise a good point about compression though and there are other factors to considder with squish height such as squish velocity and trapped end-gas.

At 10,000 RPM reducing deck height from 1mm to .5mm will jump the squish velocity from mid 20s m/s to low mid 30s m/s. End-gas will also be reduced from about 11% of head volume to about 6%. End result is more of the fuel that goes in gets burnt and converted to power at the crank.


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## Trigger-Time (Nov 5, 2008)

For the heII of it, I used a 1 mm cylinder gasket on an 026 = 130lbs compression.

Same saw, piston and cylinder with .5 mm gasket = 160 lbs compression

.5 mm run so much better.


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## timberwolf (Nov 5, 2008)

Now just take that .5mm gasket out and see how it runs. 026 is one saw that it can work for. 359 is one it does not work well for.

So much depends on the other factors. 026 is very choked on intake, filter and muffler outlet, really that saw can't take any advantage of higher exhaust durration and more RPM as it is just able to breath enough stock, in that case the lower exhaust and torque gain is good, but do some porting work and unrestrict exhaust and intake and you will want to have the exhaust back up to stock numbers or RPM, top end and cut times will suffer.

359 is not restricted on the intake side as is the 026 and it will show slower cut times and lower RPM with base gasket out. 

Interesting 026 does not need much if any raising of the exhaust port durration to port the saw, 359 does need more in the way of raising the exhaust port.


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## Trigger-Time (Nov 5, 2008)

I have a roll of .4 mm gasket, I may try it first.


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## mcb (Nov 7, 2008)

how common is it to hotrod MS290's? any proven tricks or no-nos on the farmboss?


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