Differences in compression ?????

[motoman.5150]

I have a 365 with a big bore kit and a 2171 with a big bore kit both with no base gaskets my 2171 has over 180 lbs. of comp. yet my 365 only has 160 also have 2 350's both with brand new cylinder kits, same one, and 1 has170 lbs. and the other only about 140 can you tell me why they are so different, the only facterfor the comp. is rings and combustion chamber and it s the same,I might be able to understand the first 2 saws because the 2171 is good and broke in but the 350's were put together on the same day ????

 

[angelo c]

Machining?
Mold quality ?
Monday Morning Mechanic made it?
Mufflers?

any MORE?

 

[motoman.5150]

they both do have muffler mods but very near same and neither 350 has any mods, just seems like alot of difference for same parts

 

[angelo c]

I would swap out the ring sets for Chits and Giggles and see what results you get. A few .001ths in bore diameter or thickness of the rings and you could get similar results as yours.

One mans Micrometer is another mans Hammer >>>

 

[angelo c]

I wonder if "case" dimension variation or Rod length differences might have the same effect as well. Just thinking out loud. Maybe even bearing tolerences ?

 

[motoman.5150]

not a big enough a deal to tear them down i was just curious

 

[Husq445]

not a big enough a deal to tear them down i was just curious

30lbs is a big difference. Something is off. 5 or 10 ok, but 30?

 

[1steve]

I don't think the Chinese care about consistency, quantity not quality.