Who is running a ported/modded milling saw?

[BobL]

There has been some discussion in another thread in this forum about porting and modding powerheads. I thought it would be useful to know the extent and success of this in milling saws.

For those that have modded and/or ported

1. What are the details of the mod/port?
2. How much and what type (wood, size) of milling do you do?
3. How long have you been running the modded/ported saw?

A couple of general questions for porters.
- How far would you go with porting on a saw that is to be used for regular milling in over 40" wide hardwood?
and
- How far would you go with porting on a saw that is to be used for occasional milling under 20" wide softwood?
and we want these saws to last for a decent length of time (say 7 years).
The answers will no doubt be saw dependent but anything you can add about the type of saw how you went about it etc would be worth sharing

 

[woodsrunner]

Great idea

Great idea for a thread Bob!!! I've been mulling this over a lot lately and look forward to everyones replies and thoughts on this topic.
Scott

 

[Brmorgan]

My 395 is muffler modded and I wouldn't hesitate a second to do it again. Runs much stronger and cooler. My 660 was professionally muffler modded before I got it (I was told by Walker's, but have no proof), and I never did check the port while the muffler was off so I'm not sure if it had been ported at all. It doesn't run as if it is. I mildly ported my 181SE this winter (1st port job) and will be trying it out on the mill this season, though I don't know how much I'll actually mill with it since I have 5 larger saws to work with. It can sure cut firewood though! I removed the base gasket also to increase the compression to 180 LBS, though this also increases the heat generated by the engine so it probably wouldn't be ideal as a prolonged use milling saw. I'll see how she does.

 

[excess650]

My 066 has a Bailey's big bore kit to increase displacement, but not port modded. In fact, the ports are smaller than the OEM Mahle cylinder for the 066/660. The muffler is a Stihl dual port. Compared side by side with my 660 which also has a Stihl dual port, the big bore has noticeably more grunt.

The 3120 is stock. If it had a spark screen from the factory, it was gone before I got the saw. I would not dual port the muffler on this beast as it is LOUD. The vast majority of US spec 3120s don't have an adjustable H on the carb, so tuning on top end is done by way of changing the jet. Mine seems fine, so I'll leave it alone.

Having a cylinder ported to increase torque would be a good thing. Torque rules on the Alaskan! I don't think raising RPM above factory spec would be good for longevity, but with the increased rpm comes the increased torque. I'll continue to run my milling saws tuned rich, and with more mix oil than factory spec.

Now that I've ordered a bandmill, the Alaskan and Mini Mill will be relegated to cutting slabs, squaring cants, and making large logs millable on the bandmill.

 

[Taxmantoo]

I posted this on another thread, should have posted it here instead:

If I had a saw torn down to modify it for milling, I think I'd want to have the piston fully coated with ceramic insulation on the crown, permanent lube on the skirts, and heat transfer coating inside (that last is probably more important on a four stroke with oil splashing under it). If I were to buy the coatings and coat the piston at home, I'd ceramic insulate the combustion chamber and exhaust port too, the idea being to keep the cylinder as cool as possible.

http://www.techlinecoatings.com/CoatingProducts.htm

 

[gemniii]

Resurrecting an old thread for a vote and a question.
I just acquired a second 660. This has a blsnelling woods port and a blsnelling muff mod.

As you can see he really opened it up. It roars. However, I also have a dual port muffler cover from Baileys. It presently is on my backup 660. Any advantage/disadvantage of swapping the DP cover onto the blsnelling modded muffler (and retuning)? Can you get to much area for milling?

I had seen some thread (which I can't find right now) that mentioned optimum hole size.

So far I've only milled with it with my 28" bar, cuts like butter.

 

[splitpost]

stock 660 with factory dual port slot opened up and internal baffles removed,Oh yeah! its loud

 

[BobL]

Resurrecting an old thread for a vote and a question.
I just acquired a second 660. This has a blsnelling woods port and a blsnelling muff mod.

As you can see he really opened it up. It roars. However, I also have a dual port muffler cover from Baileys. It presently is on my backup 660. Any advantage/disadvantage of swapping the DP cover onto the blsnelling modded muffler (and retuning)? Can you get to much area for milling?

Somewhere I seem to remember Lakeside had a thread that recommended the opening to the atmosphere be more more than 85% of the exhaust port opening.

It is possible to run out of H adjustment by opening up the exhaust too far - then you need to increase the main jet diameter.

You could also remove the spark arrestor for a bit more flow if you can still retune.

cheers

 

[mtngun]

The dual port cover is not recommended for milling. It does not increase power. It does blow hot exhaust onto the operator's hands.

 

[gemniii]

Somewhere I seem to remember Lakeside had a thread that recommended the opening to the atmosphere be more more than 85% of the exhaust port opening.

It is possible to run out of H adjustment by opening up the exhaust too far - then you need to increase the main jet diameter.

You could also remove the spark arrestor for a bit more flow if you can still retune.

cheers

Found the thread http://www.arboristsite.com/newreply.php?do=newreply&p=435297 and a critical (to me) post:

I just ignored the existing hole on my 066 and added the factory dual port. It's SO much larger than the original that modding the original makes no difference. I published the measurements of the various original exhaust sizes and the dimensions of the factory dual port some time back.


Here's an extract from the orginal thread:




The standard muffler on a USA post 1998 066 or MS660 has an exit hole of 0.43 inch diameter. Prior to 1998, this was 0.63 inch. In 1998 they also made changes to the cylinder porting to reduce emissions (not sure what they did).

The USA Magnum muffler front has a internal rectangular hole (with rounded ends) of 1/2 x 1 9/16 inches feeding an external slot of 5/16 x 1 1/2.


So, area of outlet:

Prior 1998 : 0.311 square inches
Post 1998 : 0.145 square inches

Add a Magnum muffler front to either : add 0.469 inches... (and it might be a tad more than this).

Yes, the saw winds up pretty good with a magnum front and you have to remove and reset the limiter caps to richen the carb.

The internal box with all the smaller holes in it is the same for all the 066 mufflers.

That Post 1998 size sure seems puny in comparison to the other numbers!

NOTE: anyone messing with an earlier 066 muffler needs to make sure they have a main carb jet of at least .72mm. The "red eye" 066's had a main jet of .66mm (because the ignition limited the max rpm). Stihl published a tech note to say that using the .66 jet and turning up the rpm will result in piston seizure... as the saw couldn't get enough gas at high rpm.



If you want a screen, the "factory" option from 1995 is the way to go on the 660.. and if you have a cage, yes, drill out the end a little.

So it seems if I want to go whole hog I might need a larger jet to make sure it doesn't burn out.

 

[mtngun]

You didn't listen to what I said.

A modded single port is fine. There are no additional power gains by adding the dual port cover. Just increased noise and heat where you least want it.

I've tried it both ways, and went back to a modded single port.

I never changed jets, never heard of anyone who had to change jets. You would only need to change jets if you ran out of adjustment on the H screw.

 

[cowboyvet]

I just completed a big bore kit with NiSi coating for my 066. Minor port work and stock single port muf opened up. I'm still taking it easy to break it in but can feel big difference in power. I also tend to run the saw a little richer and 40:1 mix for milling. I like to get as much power as I can but still would rather go slower than cook the saw.

 

[gemniii]

You didn't listen to what I said.

Your right - I didn't listen to or READ what you wrote. If you had noticed our posts were 3 minutes apart. I was writing while you posted.

A modded single port is fine. There are no additional power gains by adding the dual port cover. Just increased noise and heat where you least want it.

I've tried it both ways, and went back to a modded single port.

I never changed jets, never heard of anyone who had to change jets. You would only need to change jets if you ran out of adjustment on the H screw.

I have no way of determining power gains. I don't have a dynamometer. Based on reading in the muffler mod threads more hole, (up to 85% of exhaust port) gives more power.

Your earlier post:

The dual port cover is not recommended for milling. It does not increase power. It does blow hot exhaust onto the operator's hands.

Seemed to indicate that the dual port cover does not increase power. Everything I've read indicates it does.

I milled twice with the dual port. I didn't notice the extra heat on my gloves and the extra noise was not noticeable thru my earplugs and "thunder 29" hearing protectors.

The comment on trading jets was in a quote from Lakeside

Stihl published a tech note to say that using the .66 jet and turning up the rpm will result in piston seizure... as the saw couldn't get enough gas at high rpm.

in his thread http://www.arboristsite.com/showthread.php?p=435297#post435297 .

I think in the reading I've done I've read of one guy changing jets. To me changing jets on a good carb is much more difficult than swapping in a DP muffler cover.

The hole in the blsnelling modded muffler is 3/4" x 9/16" or about 0.42 square inches, thus close to the size of the Magnum muffler Lakeside refers to, but much less than that of a Magnum plus pre1988 original. Or that of my DP muffler.

which looks to be about 0.7 square inches.

Bottom line - I want to maximize power w/o changing the carb. The snellerized hole is a lot less than a dp plus original. I'm concerned if the snellerized plus the dp may be too much.

 

[Rusty-880]

Firstly I want to point out I am not trying to give the impression that I am a 2 stroke guru. These are my personal opinions based on research and playing with V8s.
I run an 880 with muffler outlet approx 1 1/4" dia- nosier but no prob tuning.
Stock ports I believe are too small, time:area ratio for peak power works out to just under 5000rpm for exhaust and intake and 8000rpm for transfers. Considering stihl says peak power is at 8,500 I see this as seriously mismatched ports. I have ported another cyl matched to 10,000rpm but havnt had time to swap them over yet.
Rule of thumb for safe rpm is max 4000 ft/sec. .166*stroke inches*rpm. On an 880 I will keep no load speed at max 13,500-13700, 500rpm below. How often do you run wot with no load?
I tune the same as if I am cutting firewood, no richer. Running rich reduces power aking the saw work harder and also gives a carbon build up. Carbon will give hot spots which can lead to pre-ignition. Saw is over two years old and always been on the mill will no trouble.
Reducing squish, while increasing comp can also reduce the tendancy for detonation. On V8 with comp as low as 7.5:1 you can have pinging if the clearance between piston and head is too large. Cool air/fuel mix clings to piston and cyl surfaces. If clearances are reduced still giving a safe clearance cool air/fuel is trapped in this space and wont preignite.
Extra oil in the fuel mix will drop the octane rating and while this has no worries to a stock saw it may gives problems in a modded saw.
I would like to make an expansion chamber for the saw, mill design allows. In my understanding it will allow the engine to use the full 122cc instead of approx 75cc( top of exhaust port up) in the case of the 880. Pipe is tuned to both extract from the cyl and ram fresh gases that have followed back into the cyl for a greater cyl pressure.
Not everyone will agree with these thoughts but it cant hurt to share

 

[Justsaws]

There has been some discussion in another thread in this forum about porting and modding powerheads. I thought it would be useful to know the extent and success of this in milling saws.

For those that have modded and/or ported

1. What are the details of the mod/port?
   Stihl 660 on 24" mill
   Large exhaust port in a flat plate for the front muffler cover so it points down. Lots of room for spark arrestor screen.
   Stihl 660 on a 16" mill
   Dual port factory muffler with original side port opened up.
   
   
2. How much and what type (wood, size) of milling do you do?
   Not much total board feet. Typically 4'-10'long x 12"x 24"dia logs. Hardwoods such as cherry, locust, ash, etc..
   
   
3. How long have you been running the modded/ported saw?
   These saws have been on the mills for around 3 years.

A couple of general questions for porters.
- How far would you go with porting on a saw that is to be used for regular milling in over 40" wide hardwood?
and
- How far would you go with porting on a saw that is to be used for occasional milling under 20" wide softwood?
and we want these saws to last for a decent length of time (say 7 years).
The answers will no doubt be saw dependent but anything you can add about the type of saw how you went about it etc would be worth sharing

I have used lots of different saws and always go back to 660s. I have modified P/C for them but found that in the size of wood that I am after the increase fuel consumption does not match increased production. Aux oilers, modified clutch covers and no air filter covers on both.

I got a about a year out of a modified 2095 and 1100CD before the rod bearings went out. The 2095 and 1100CD were great saw for milling in stock form and I should have left them alone. If parts were easier to get and less expensive I would still be using the 2095s.
I did not leave the modified 660s on the mills as the increased fuel use worked out better with a 3/8"x8x36" setup and typical saw use.

The duration of run time would be the determining factor for how far I would modify a saw. Taking a saw and increasing its under load operating RPM for half a minute per load is much different than doing the same if the under load time is mulitplied 4x+. It was always bearing failures, not heat. Heat is easy to control.

 

[Stihlman441]

Somewhere I seem to remember Lakeside had a thread that recommended the opening to the atmosphere be more more than 85% of the exhaust port opening.

It is possible to run out of H adjustment by opening up the exhaust too far - then you need to increase the main jet diameter.

You could also remove the spark arrestor for a bit more flow if you can still retune.

cheers

This may help,i have a snellerized 660 with woods port,milled cylinder,carb limiters pulled,pop up piston,ceramic coated piston crown,upper cylinder and exhaust port,timing advanced 5 deg and the same stock port opened up as much as possible.I have been wondering if an extra port would make any differance so yesterday i removed all of the inner baffle and added another port.
This is what i found when i started it,the idle speed increased about 300 rpm at w/o was still the same 13900 rpm as before and is still rich at that.I have not got around to doing timed cuts as i did before the extra port to see weather there is any gains.

 

[smokinj]

Dont really see the point in modding a milling saw.(Its slow work modded or not) Milling chain is another story!

 

[stihl038x2]

dont really see the point in modding a milling saw.(its slow work modded or not) milling chain is another story!

+1

 

[srcarr52]

I have a 288XP that is ported (transfers pushed out bottom of cylinder, exhaust/intake as wide as they'll go), crankcase stuffed and ignition timing advanced. I run it on a 32" 0.050" gauge setup and I have been milling mostly walnut around 20-24" diameter. I run a full comp 5/55/0 grind chain with file-o-plate rakers driven with an 8 pin on the saw. It does alright but it's a little under powered on the larger logs and you have to make sure you are not pushing very hard and pulling the saw down. It's faster to let the saw rev then to push hard and bog it.

I'll probably build a ported 394XP for milling in the future. It will probably be a dedicated millings saw (all torque build). Maybe even leave the fuel tank off and mount a remote one on the opposite side of the mill for balance and run a remote throttle.

 

[BobL]

I have a 288XP that is ported (transfers pushed out bottom of cylinder, exhaust/intake as wide as they'll go), crankcase stuffed and ignition timing advanced. I run it on a 32" 0.050" gauge setup and I have been milling mostly walnut around 20-24" diameter. I run a full comp 5/55/0 grind chain with file-o-plate rakers driven with an 8 pin on the saw. It does alright but it's a little under powered on the larger logs and you have to make sure you are not pushing very hard and pulling the saw down. It's faster to let the saw rev then to push hard and bog it.

I'll probably build a ported 394XP for milling in the future. It will probably be a dedicated millings saw (all torque build). Maybe even leave the fuel tank off and mount a remote one on the opposite side of the mill for balance and run a remote throttle.

Look forward to seeing what you come up with.