OS61 FX problem
 

I am stumped. New bearings, sleeve and piston last year. Run 10% Byrons, 12x6 prop. Engine wont keep running at any needle valve setting. Not overly hot, runs about three or four minutes and quits. Tank even with needle valve, all new lines, clunk not stuck, blew out needle valve, new OS8 plug. No kinks in line anywhere. Sags at high and medium speed under load. Starts easily. Restarts easily as well-- just wont stay running. Have tried to richen, lean, neither helps. Any ideas before I send it back?

PLEASE!

Forgot-- new O ring on needle valve. Engine ran fine till about three tanks ago.

OS61 FX problem
 

What is the oil content of your fuel. An engine that runs only for a few minutes and quits indicates it's getting too hot.

O.S. states that the oil content should be no less than 18% by volume.

Also check the idle mixture. Many times it's too lean. Richen it a LOT and work with the high-speed needle first. Then go back and get the idle mixture adjusted once you have the high-speed sorted out.

If all else fails, put the engine on a test stand and see if you can get it running well. If it runs well on the test stand and not in the model, then the problem isn't the engine, but the combination of the model, the engine, and the fuel system.

If it can't be made to work even on a test stand, it should be sent to the service center.

os61
 

Bill Baxter

Thanks for your input. This engine as well as all my others run on Byrons 10% which is 16% oil, castor and synthetic. Nver a problem from overheating on any that I know of. This engine has been great for about a year since its overhaul. It is in the mail to you. Shoould have it Fri AM. Most of our clubuses the same fuel and no problem from any of them.

Thanks