91FX getting hot
 

I have flown this engine very rich... too rich maybe... I have been flying it in a plane for one month now... and this morning it all of sudden started overheating... I could see no more smoke and feel that I have no more power... I have checked for leaks, nothing... I have changed nothing... just overheating for no reason... I have now taken off the cowling to try sort it out next time I fly it... I fly the engine pretty much full throttle all the time for 4min at a time before I land... at half throttle the engine just seems to be boggy, so I fly 3/4 to full all the time... is this ok? could this also be why its so hot? I don't know... good response also, I have set the LSN to 1.5mm gap like the manual says... so the LSN is not too lean... the only ideas I have is to just change fuel line which is really new, change plug maybe... I use a 13x8 prop with 10% omega pink fuel... castor content, not synthetic... who can help?

RE: 91FX getting hot
 

If the engine's overheating, then it's not getting good airflow, not getting enough fuel (lean), it has too much load, or it has an air leak somewhere.

From your description, you may need to richen the idle mixture and then work with the high-speed mixture. The settings described in the manual are only starting points. You have to adjust from there. If the idle mixture's too lean, it can affect fuel flow at all throttle settings. Just richen it so that you know that its "stupid rich", and get the engine running. Run it up to full throttle and get the mixture properly-set. Then, retard the throttle and work with the idle mixture.

Finally, go through the fuel system to ensure that you do not have any air leaks or vibration-induced fuel foaming (air agitated into the fuel). Either will cause leaning of the mixture.

RE: 91FX getting hot
 

i used clean 5% fuel this morning with a R5 cold plug... still not better... will need to probably strip it down and check whats happening inside...