hi,

i have an old OS 61 ABC that used to work fine until now. there are 2 problems with it. the first is that it gives me good rpm's till about 80% throttle and then it just dies down. i've tried making it rich and lean but nothing works.
the other problem is that the engine doesn't start with a starter. it sounds like it's flooded but it's not. it starts with the hand and sometimes with only one flick but not with the starter.
if anyone has any ideas on whats wrong then please let me know.

thanks,

neel

Neel,

You may need to check the fit of the piston and cylinder liner. If it's worn, then the engine will tend to not run well once it's warmed up to operating temperatures.

An ABC or ABC-type of engine should have a bit of tightness when the engine's cold and the pistion is moved to Top Dead Center. This would be noted with the glowplug removed.

If the engine does not have that tightness, then the fit is too loose.

If your engine is the O.S. Max .61 FSR, piston/cylinder assemblies are still available. In the U.S., the part is:

OSMG4934 26703200 CYL & PISTON 61SFN US$114.99

The piston/cylinder assembly for the .61 FSR and the .61 SFN are the same.