Hey guys my os 91 hasnt been run in about 3 years. upon looking over the engine alot of rust was inside, I used navy jelly i bought at lowes did the job. Its not sucking gas with very little compresion, could it be the piston rings ?

rust might have eaten some of the piston ring away as well as the liner and a bunch of other stuff. making a sufficient gap to loose compression (piston rings and sleeve), If I where you I would change piston liner (if it had rust) and the piston ring. Also check the carb, SPECIALLY the needle valve assembly which tend to get rusty and give everything a good cleanup. Change anything you see damaged. 3 years without use can be pretty tough on this engines. hope this helps!

You can find the replacement part here:
http://www3.towerhobbies.com/cgi-bin...I=OSMG0591&P=Z

thanks rzarikian, im ordering new ring for piston

Ahhhhhhhhhhhhhhhhhhhhhhhh: The price we pay for not doing things right the first time is amazing. What if??? ENJOY

garygee :

Remember to BREAK-IN your engine after you install the new rings! do it per manual exactly as if it were new. I know its kind of boring but it will give you way better performance once you do it. You can download the manual at osengines.com

Yup, had that problem before. Most likely your ring.

thanks guys

also if rust was in the engine you need to replace the bearings or your new top end will be ruined by the bearings!!!!!