Roggy-

I think this is unlikely since you say it runs for 30 sec., but any chance you took off the intake & exhaust and got them back on in reverse?? I believe the threads are the same for this engine and I've seen eBay photos of engines with them installed backwards. I *think* the exhaust comes out the back of the head and intake is on the right side (facing it from the rear). My T4-40 is that way. If any question, I could call a friend who has an 80 and ask him.

Another question is whether the belt was replaced or removed/reinstalled since it ran well 2 years ago? If so, the timing may be off.

There is no valve "adjustment" possible, other than belt timing, nor "sticking" because this engine has a rotary valve, not poppet valves like most 4-strokes.

Maybe there's some crud in the carb's fuel inlet? Remove the fuel line, back the needle valve way out and blow vigorously into the intake, or blast some fuel into the intake to backflush (first rotate crankshaft so intake valve is closed). Hold some tissue near the inlet to catch the crud so you can see and admire it.

If all else fails, set the high speed needle valve open about 3 turns to begin. Thats probably too rich for proper running. If your carb is similar to the one on my 40 (might not be), back the low speed needle out so that at full throttle, it's backed out and clearing the end of the spraybar. Check that closing off the carb intake with your finger (choking) and turning the prop through at least 2 full turns will draw fuel from the tank.

Remember, persuasive insults must be in German.

-Dave