HeLLo Guys I know this is old hat by now but I have two planes one with a como 40 its upsidedown and the mds 40 on my trainer( right side up ) I have a hard time starting the como Does anyone have any hints or tricks ? Thanks , Mike

Try really hard to avoid flooding the engine before starting. If you use an electric dtarter, try starting it without priming it first. With the engine upside down, extra fuel can "pool" in the glow plug making it ineffective.

If you have an electric starter, try cranking the engine over without priming, then put your finger over the exhaust outlet on the muffler while cranking to pressurize the tank and shoot some fuel to the carb...JIM

Ok I 'll try that thanks guys ! by the way I think they look better upside down they just look more like a plane what is the disadvantage ? just curious

You've already seen the biggest disadvantage to inverted mounting, it makes starting harder. Inverted engines also don't always idle as well, and the idle mixture setting is more critical. This is all caused by what Minn said, excess fuel and oil pooling in the plug.

To get an easier to set, and slower idle with an inverted engine, some guys go with an onboard glow lighter. But I've seen guys at my field run inverted 4-strokes with no on-board glow, and absolutly no problems at all, nice idle and everything. And I've seen guys never manage to get an inverted engine to run right. So, YMMV. In general I think it's a little harder to get everthing just right on an inverted engine, but once you get it right, you shouldn't have any problems.

I personally find side mounting, with the muffler down, is the all around easiest way to run an engine. If I ever get around to designing a trainer, that's how I'll mount the engine. (It's harder to flood, since the excess fuel will pour out of the muffler, though you can still flood the crankcase).