tuning my os 32 [Archive]

Sential

05-15-2004, 11:04 PM

i was just looking for some help tuning my os32sx-h.
i know that they have a problem ideling sometimes but this is crazy, i get it to run ok in flight (meaning that it will run, not at full power though) and as soon as i bring it down and in to idle it will almost always die. i have about 4 and 1/2 gallons through this new engine. have tried all tuning specs from os and new glow plugs. (using os a-3's) I have changed out the clunk lines in the tank and header tank, checked the throttle geometry numerous times. im at a loss...

capebob

05-16-2004, 07:33 AM

First change to an OS 8 or Enya #3. Second, remember that the tuning specs. from OS are only a guide and the proper setting will change depending on the altitude of your flying site and the ambient temperature and pressure at the time you are flying. Having said the above, and after you change you plug and you are still having a problem you are either too rich or too lean. There is no other adjustment to be made on our little engines. My best advice is to seek an experienced person to help you get your engine set-up correctly. If no one is available you can follow these steps.

1. Set your low speed needle valve at the factory recommended setting and do not touch it again until your engine is producing good power, good smoke, and not overheating. Make all adjustments with the high speed needle.

2. Adjust your high speed needle so that you have quite a bit of smoke coming out of the exhaust and after a prolonged run you can put you finger on the back plate of the engine and not have to jerk it away immediately. It should be quite warm but not hot to the touch. If you have little or no smoke you are too lean. If you have lots of smoke but no power you are too rich. Make adjustments accordingly.

3. After you have the high speed needle adjusted try to idle. If the mixture is obviously not correct, i.e. the engine won't idle, bump your idle speed up until it will and do the pinch test. With you engine idling as slowly as it will, pinch your fuel line and check engine speed. If the engine quits immediately your are too lean. If the engine runs excessively long, over 4 or five seconds you are too rich. When you pinch your fuel line your engine should slightly increase in rpm and then quit. Make low speed adjustments accordingly.

4. If it were this simple it would be easy. There is some interaction between the low and high speed needles in many of our engines. So after you adjust your low speed needle you may have to adjust your high speed needle a click or two one way or another.

Now that you have your engine purring like a kitten :clappp don't expect that you won't have to ever touch a needle valve again. Ideal settings will change as the temperature changes. You may find that if you start flying on a 60 degree morning fly your last flight on a 95 degree afternoon, you will have changed your high speed setting several clicks.

I hope this helps.

Bob