I am trying to break in my .61 FX. It is set up according to the manual in terms of needle turns etc. However the engine is mounted upside down as opposed to a normal trainer where the engine is upright. I try to start it and the engine will not turn over no matter how hard you pull, will break something if i pull any harder. However if I flip the plane upsidedown so the motor is upright not only can I turn over the engine easily but I can get it to run beatifully. When I start to trun the plane over again so I can taxi the plane around the engine stops immediately as soo as the engine is upside down again.

Is there anyone who can help me out.

Thanks

Ickeboggle

It sounds like you are running a bit rich, and the engine is flooding. Inverted engines take a little doing.

Don't prime quite as much as you are when getting ready to start it. You are basically filling the cylinder with liquid fuel, and that's causing a hydrolic lock, and yes, you can really break things this way if you aren't careful.

If you can rotate the engine even a little off totally upside down, it might help.

You might also try an idle bar glow plug, or a hotter plug, it might help the idle and low speed running.

Just re-read your post. Many guys break in an engine upright, then only mount it inverted when it's broken in fully, specifically to avoid this kind of problem. New engines don't run well at slow speeds anyway, and inverting it makes it worse. If you can mount the engine upright for a few tanks of fuel, then invert it and run it just a little richer than full power, you might have more luck

Dear Ickleboggle:

Unfortunately inverted engines need some special TLC when it comes to low end. Some guys have no problems. Others, like myself, can never get the low end right. You need to lean up the low end a little at a time. The low end screw is located in the throttle arm nut where it connects to the carb. Start the plane and turn the low end screw in about 1/4 turn. Throttle up and down. You will find a point (hopefully) that will allow the engine to run inverted without stalling. I myself don't have the patience so I put an on board glow driver in all my planes with inverted engines. The on board glow keeps the glow plug lit at low rpm and allows a nice low idle without stalling.

Good luck.

Pat

I have this same engine, and what a powerhouse. I had inverted on a TT Cloud Dancer and didn't have any trouble at all. It sounds like montague has hit it on the head when he said it sounds like you're hydrolocking. This can be very bad. If it feels real tight, turn the plane upside down and see if you lose fuel from your muffler. Once it's drained, you should have no trouble firing it up. Good luck