OS 91 Tuning info [Archive]

EricLarson

04-16-2005, 12:03 AM

For anyone who is intirested, I put up some info on motor tuning and my opinions on my site. The info is geared for the OS91 but applies to lots of motors.

sdixon747

04-16-2005, 10:50 AM

Thanks Eric

That's some great info!

Steve

Mike Fortin

04-20-2005, 07:28 PM

Great Info Eric...Thanks!

Daniel Jetschin

12-05-2005, 10:53 AM

I have a few questions, as i was running in my new OS 91 it's got up to 140° C the 3rd or 4th tank, but it LOOKS like new... And i had some flights where it did not switch back to idle right after hitting throttle hold, too .... Did I ruined this Engine now?

DavidH

12-05-2005, 11:22 AM

Hard to say if the engine in riuned or not because of a couple of lean runs. It would take listening to the engine run. Or visually inspecting how the sleeve and piston look. If you ruined the engine, it will most likely not run at all or it will run very poorly no matter how it is tuned.

David

Daniel Jetschin

12-06-2005, 02:57 PM

It runs great, but dunno if it will ever reach it's full power level as it would without lean run. We will see..

Daniel Jetschin

12-08-2005, 04:04 AM

Now it's finally fooked after the carb came loose again and the temperature reached 170Â° C... :arggg: It's not that you can't use it anymore, but it'll never reach it's top performance....I'll go with a new liner and ring, or the new SZ ... :smokin:

Yellowjacket

02-18-2006, 08:59 AM

When I was still running my 50’s a buddy of mine seized one from pushing the motor to hard with out letting up on it. I can usually run them leaner because I load and unload pretty quickly.

After I tore it down I cleaned up the piston and broke the ring loose.
The motor ran surprisingly well but it didn’t make the power it did and the idle was terrible.

In my experience when a motor has been lightly damaged or excessive wear I notice it won’t idle as slow as it did before. I’m guessing it’s the lack of compression.

Bill

Gary O

02-20-2006, 05:07 PM

Heat is the death of these engines. One lean run can drastically reduce the power and life span. Over speeding is another one that doesnt' seem to get near the press as running lean but it has about the same effect. Running at peak rpm all the time and then figure in the loading and unloading and it doesn't take much to stretch a rod.