Hi Guys,
Here is my problem. I have a tower hobbies 75 2 stroke. It has run very well for about 2 years now. This engine was put on a self designed 60 size profile plane for 3D training. It flew very well for about 2 months now until a couple of days ago. I was flying for the 4th time that day, practicing Harriers. Flying very slow with spoilerons and low throttle. Suddenly, the engine died. I was able to do a good dead stick landing... on the wheels and no nose over or anything on the runway. When I got out to the plane, the engine smelled HOT. I let it cool and called it a day with that plane. The next day I cleaned the engine and checked everything over. (Tank, lines, case, controls, muffler, glow plug, etc.) I replaced the glow plug with an OS A3 just as a precaution. The engine starts transitions and runs well at full throttle on the ground. It does feel as though there is a small loss of compression, but It doesn't seem like much of a compression loss. After take off, I get about 1 to 2 minutes of flight time when it dies. Retrieving the plane, I thought the engine might be a bit lean and so getting hot. (It didn't smell hot or feel excessively hot when I got to the plane)

I checked everything again with nothing found. I re-padded the tank (No evidence of foaming, but padded it anyway). I also richened both the low end about 1/8th turn and High speed about 3 clicks. On several (3) more flights ... same thing. I have richened everything again 1/4th turn low end, 4 clicks high end. It is obviously rich now and running as you would expect loads up at idle slower sputtering transition, then lots of smoke and lower power at full throttle. Still only does 1 - 2 minutes and dies.

Given this, can anyone give me some thought as to as to where to go or what to do next?

Thanks for your help in advance

The A-3 is a HOT plug. Might cause preignition in summer? A-8 would be a normal plug.

Enjoy,

Jim

Check the internal plumbing of the tank. It sounds like the clunk line has come off. If not check for air leaks or pin holes in the lines including the internal tank lines. Your best bet would be to completely replace the plumbing both inside the tank and external to the engine.

Hello again, As I said, I have already checked the plumbing of the tank, inside and out. As a precaution, I have already re-plumbed everything including the tubing between the needle valve and the carb. It still dies after 2 to 3 minuted of running. I swutched to a A-8 glow plug and other than the fact that he engine is very rich on the groung, it doesn't seem to make and difference. Any other thoughts?

Fuel foaming caused by vibration will effect you this way.

Enjoy,

Jim

On this engine I believe that you can remove the plug in the carb and the high speed needle will simply screw into it. This converts this plane from a remote needle to a conventional design. Try it this way to see if your remote needle is leaking air. This would cause the engine to lean out in flight.

That's a very good thought Sport10. I have seen several remote needles cause this exact problem.

Another thought would be to install a fuel filter between the tank and carb. The fine wire mesh helps prevent fuel bubbles from reaching the carb.

[8D]MMM I THINK ITS THE PLUG THE OS #8 PLUG SHOULD BE NICE FOR THAT ENGINE IUSE #8 TRIED THE A3 BUT ENGIEN KEPT CUTTING OF PUT A # 8 WALA PROBLEM SOLVED JUST MY 2 THOUGH GOOD LUCK

I also agree that the OS A3 glow plug is too hot for this engine, as it is OS' hottest two-stroke plug, even with as little as 5% nitro. The OS #8 is the right heat range, as is the Enya #3, but the K&B-1L is also the right plug, yet it costs less than half of the aforementioned brands.
You get nothing by paying more, in any respect.

It was not too long ago that you could buy 12 glow plugs for $10...
In the case of the OS #8, or the Enya #3, it wouldn't even be enough for two...