ORIGINAL: marktur
Blue - you need to use the fuel tank the same way everyone else does, and also the way it was designed for - clunk towards the REAR of the plane. The inside plumbing - clunk should come about 1/8 - 1/4 to the end, but not touch - it should flop around to the "bottom" of whatever angle you're holding the tank. There's no other correct way to do it without using a pump.
If you're not just leaning out the motor too much - this is easy to do with a pusher, BTW, because you're not getting the prop-blast you're used to with a tractor setup. You can't tweak it to "max rpm" on the ground - you have to find that spot, then open the needle a bit more. When it's in the air, it will be moving forward, thus creating less resistance on the prop, allowing it to "unload" and acheive higher RPM. This is when it heats up and you get into trouble. The fact that sometimes when you throttle back you can save it is another BIG hint - you throttle back, the motor cools and begins to run properly again.
If you cannot get it to quick going dead stick even with a rich ground setting, I'd look into the following things:
1. Make sure all the head bolts are tiight.
2. Make sure there's no fuel leaking out under compression around the glow plug
3. Use an external fuel tank - just for testing - to verify it's not a fuel tank or line issue
4. When you're testing for a good setting, have your helper hold the plane vertically, with the nose DOWN (leanest cast conditions) and re-tune.
5. Change to brand new fuel, and put in a GOOD recommended glow plug.
6. When it's running, if you tap on the needle valve, and the motor changes, it may be that you have a bad 0-ring in the needle, or the o-ring sealing the carb to the motor. Unscrew the needle valve and try to see if the o-ring is damaged, and also try blowing fuel backwards from the exhaust feed, fuel should come out of the needle valve.
If none of these work, I'd say it's time to get a new piston and sleeve for the motor, or perhaps just get a new motor. It's not worth risking a nice plane for an unruly motor. Spend $90 and get the Tower - that's the deal according to some of the guys posting here. I'm running the OS 55AX, and I love the motor, but I've paid probably $150+ for it. (Can't remember now - but it's RELIABLE and has excellent power).
Whatever you do - don't fly it unless it will idle for a good 30 seconds without shutting down, and can also run at full throttle for 30 seconds without slowing down RPM's.
Finally, I do the "pinch test" when I think it's tuned properly - while at full throttle, I pinch the fuel line to the needle valve. It should make the engine INCREASE in RPM, if it sags or shuts off, you're too lean - open the needle a few clicks, and try again.
Hope that helps
Mark