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View Full Version : os 91 ring in ys 91 st


chrsvct
05-31-2008, 06:25 PM
Has anybody tried an os 91 ring in a ys 91 st, they are the same bore (27.7 mm), but I dont know about the thickness of the ring itself, I ordered one from tower to try, I was just wondering if anyone had tried it, cant seem to find a ys 91 st ring and the 91 sr is a 27mm bore so it wont work either

Thanks,

Chris

Raven_darkcloud
06-01-2008, 12:36 AM
Lets us know how it works. I know I have used many gm parts on Old Harleys so its always good to know what will work in a pinch.

chrsvct
06-05-2008, 11:45 PM
the os 91 fx piston ring (part # 29503400) is almost an exact replacement for the ys 91 st, the thickness (od to id) is about .001" thicker than the ys ring, but other than that they are identical.

Chris

Raven_darkcloud
06-06-2008, 12:51 AM
time for a run test then

chrsvct
06-07-2008, 08:50 AM
Well ran about a tank thru the heli yesterday just hovering around, everything was good, good compression ,starting, good idle, plenty of power, so Im going to call this fix good !

Chris