ORIGINAL: airborne14830
Thanks for the suggestions. I did fail to include the type of plane my ASP 80 is attached to. Right now it is on a profile plane called the Radical 330 40 - 46 size 2 stroke or 52 4 stroke. The Engine when i remove the glow plug always drop in RPMs by at leaset 200 - 300 rpms and in the air it has a tendency to lean in and out while airborne. any suggestions?
If your RPMs drop when you remove your glow ignitor, it could simply be time to replace your glow plug. If it is doing that with a new plug, I would try switching to a hotter plug than what you're currently using or trying a 4-stroke glow plug like a Fox Miracle plug or O.S. F type.
If your engine seems to be "spontaneously retuning" while in the air, this could be one or more of several possible problems. This could be caused by less than ideal backpressure to the fuel tank, a wandering needle valve being turned by vibration, a less-than-ideal fuel tank/fuel line setup providing inconsistent fuel flow, or all of the above. Try working through each possibility as thoroughly as you can and eliminate them one by one.
The glow motor forum here at RC Universe is full of very helpful folks with decades of experience with regard to sorting out issues like these:
http://www.rcuniverse.com/forum/forumid_114/tt.htm