Stihl Piston Ring sizes

[thompson1600]

I have been looking at ordering some piston rings for my Stihl saws. It appears that Stihl used to have 1.5mm piston rings on the 028, 038 and 075. Now it appears that the 026, 036, 044, 046, 066 and 084 take a thinner piston ring 1.2mm Is this correct? Before I order 1.5mm rings and have them not fit I thought I better ask.

Tom

 

[tkemble]

Tom,

The newer saws use the 1.2mm rings. The 1.5mm from cutters will not fit. I tried. LOL

Travis

 

[Lakeside53]

Generally the newer saws all take 1.2mm, however, some like the 034 (and there are others) started with 1.5mm and then moved to 1.2mm later, so check the piston first on these. The BR 400/420 blowers and many cutoff saws still use 1.5mm.

 

[Lawn Masters]

Ok, I am gonna ask why did they change the piston ring thickness to 1.2mm from 1.5? it dont make any sense.

 

[PWB]

Should be a better seal, less drag.

More Power!!!!!!!!!!!!

 

[cbfarmall]

Look for the threads on the thin-ring Husky 2100 vs. thick-ring. It's been talked about many times, and will continue to be. Personally, it doesn't make any difference to me but racers love them.

Chris B.

 

[Bill G]

I believe the 084 was sold with both the 1.2mm and 1.5mm. It really did not matter as the aftermarket rings are not offered in that big of bore.

Bill

 

[ErrolC]

The reason for the thinner ring relates to rpm range of the engine..slower engines use thicker rings because they do seal better..however as rpm range increases the mass of the ring tends to cause them to resonate and skip off the cylinder surface and allow combustion pressure to blow past the ring. This 1stly heats the ring directly, and 2ndly reduces the rings ability to transfer piston heat to the cylinder walls for cooling (thus causing the piston to heat further). 80% of a pistons heat is transfered through the piston rings.