036 mods

[sawfix]

does anyone know anything about bumping the compression by removing the cylinder gasket? with an modded muffler. do you need to port the thing? the dealer mechanic told me if i dont do some port work it will burn up!? anybody out there runnin a 026 or 036 with gasket removed and stock porting? thanks!!

 

[kevlar]

yep!

 

[kevlar]

What would porting have to do with compresion?Besides when you pull the gasket(do use some kind of sealant) you increase port timing anyway(slightly)

 

[sawfix]

036 mod

thanks kevlar!! i kinda thought he was blowin smoke but thought i would ask to be sure before i went ahead!

 

[kevlar]

always double check the squish with a piece of solder to make sure you have good clearance.It should be fine but heat and rpms will elongate the piston,and you don't want to hit the roof! 16 to 20 thou should be good.

 

[sawfix]

squish height

thanks! will do. and its my understandind that with the correct squish the motor will actually run cooler!

 

[timberwolf]

I don't think so, reducing squish does not change the temp the motor runs towards cooler. If anything, reducing the squish (even if compression is kept the same actually raises moter temp by improving combustion efficiency due to increased turbulance. Though the piston crown may be cooled a bit by the extra squish outflow flow.Also as the amount of unburnt end gas is reduced a greater percentage of the fuel charge gets burn efficently. this increases the amount of combustion that takes place which increases heat and HP. However reducing the squish will allow an engine to run higher cylinder temps without getting into detonation problems. 0.020 is a popular safety margine for squish height on modified chainsaws, but on the 026 you can likely go down to 0.015 without trouble.

Removing the base gasket without raising at least the exhaust port back up will result in a slower saw, at least that is what I found in any saw I tried this with. The saw will feel to have more torque, but RPM will be reduced and the loss in chainspeed will be a greater loss than the gain in torque.

 

[sawfix]

036 mod

i guess im trying to apply 4 stroke information i have learned over the years.quench sometimes called squish tends to cool hot spots reduce detonation and increase power. a running quench height of over .055 will forfit the benifits of the quench.im learnin on these 2 strokes.... how much do you need to lift the exaust port to gain the r.p.m back? i would assume the thicness of the gasket would be enough.? hey ive an addictive personality so now its screwin with saws.oh well theres worse things............

 

[timberwolf]

Yes, raising back up to the same hieght is a safe bet. While your at it, the exhaust port can be widened out some too. Take a good look ar the bevel on the stock port edges, you will want to reproduce this on the enlarged port.

Your transfer timing will be reduced by removing the gasket, idealy the transfers will need to be raised and or the port openings inlarged. But this is a bit tricky compaired to the exaust port. Intake duration will be extended a bit by dropping the jug, that is in your favor.

Your right about the tighter squish helping to prevent detonation and cool hot spots on the piston.

It is good to check the squish all the way around, sometimes they are not even side to side/front to back.

 

[sawfix]

thanks again timberwolf. ill give her a go and see what comes of it!

 

[NPKenny]

Removing the base gasket without raising at least the exhaust port back up will result in a slower saw, at least that is what I found in any saw I tried this with. The saw will feel to have more torque, but RPM will be reduced and the loss in chainspeed will be a greater loss than the gain in torque.

In summary, if a person removed the base gasket, and slightly raised and expanded the exhaust port, the saw should see noticable improvements? I am following this thread with the thought of doing some very minor porting to my 361, but I am very new to this game and would hate to incorrectly estimate what gains I can see. What type of gains can be noticed with this very slight compression and port work over just a simple muffler mod.

Thank you.

 

[timberwolf]

It depends a lot from one saw design to the next. but even a mild touch up on the engine with a little extra compression should gain you 10% or 15% on top of the muffler. Lots of info on mods, check out the search.

 

[Mr.]

Listen to Twolf he gave you some good advice. The only thing I would reinforce is to make sure your beveling of the port is atleast as good as the factory.

Fred