saw rpm question.

[Ron660]

My 372 dome piston must have been over 15 at the top of the 4 stroke, I had to put another carb on today and had lots of trimming to do and though it was tac'n' out and poped my muff and though ,right on, that feel smooth...its got to be doing 16 and as long as the wood stays small, that's were its going to stay

X-torq carb or regular 372xp carb?

 

[Ron660]

I've seen almost 16k from a couple. Over 16k on a 372.

Mike, I'm guessing those 372's were ported?

 

[win67]

Aside from 4-stroking, and lean seizures, might factory maximum RPM ratings have to do with other limitations, such as bearings, etc?

Philbert

Can't imagine factory RPM ratings wouldn't have something to do with "other limitations". Stress on the bottom end goes up as the square of speed, so a "few" hundred RPMs may be all it takes to go over the film strength of whatever oil you're using. Given the optimal weight/power ratios of the components in question, I can't imagine that any manufacturer would design the bottom end to be any bigger than it absolutely has to be to preserve a good film at the listed maximum RPM.

So, my logic indicates that any increase over the stock RPM will most likely exponentially decrease service life of the bottom end, although whether it's by a critical amount is another question. Bottom ends are definitely not the lowest stave in the barrel as far as service life of the whole saw is concerned.