Chainsaw Repair

Do these aftermarket companies keep the same port timing? or do they change things?

Do these aftermarket companies keep the same port timing? or do they change things?

Aftermarket cylinders tend to have ports that are narrower, which is a negative factor. I can't comment on the timing, but it likely varies.

Whats the difference between the two pistons?

Both the BB kit piston and the Stihl 064 piston are 52mm. The Stihl 064 piston it taller by approximately 1.3mm and can be used to raise the CR to above 190PSI. I have done several for customers and the saws run well, with no problems so far.

The Stihl piston has the same 12mm pin as the Husky however a few thousandths must be removed from the inner sides of the piston pin boss in order to clear the small end of the rod and you must make sure that you have about 2mm clearance at BDC for the crank throws. A machine shop can remove the metal from the piston, my gunsmith does it for me, quicker and cheaper.

190 psi. Can you still run 91 octane pump gas on that?  I do a lot with snowmobiles and they would never live at  190 psi. Lots of detonation, like instantly.

That's good to know. Just wondering, is there a huge difference in 190 and stock compression, as far as torque/ hp, plain old grunt feeling ?