O.K. so I set the needle back to manuf. recommended setting(1 1/2 turns). Still using previous A3 glow plug and 15% fuel. Start it up, work the trottle, and all seems fine, so I go to WOT and begin adjusting the needle, two clicks lean, and the RPM's drop, two clicks rich(at previous setting, and no change, two more clicks rich, and nothing. I go to half throttle and it dies. this time the engine was smoking hot, literally. It was smoking. I let it cool down, it still seems to have good compression when I flip the prop.
I took the head off, and this is what it looks like. Is this bad, do I need to change something here or what??????

I did notice that at the remote needle valve, it looked like the carb was trying to suck a bubble out of the needle valve, but it wouldn't break loose. That's the best way I can describe it.

2 things.

1. It shouldn't get smokin' hot. Sounds way too lean.
2. Did you read the instructions on tuning it? They work if you do exactly what it says. No changing or skipping steps.

I wouldn't worry too much about the bubble of air.

Instructions??? What are those?

Read. It got smoking hot at the manuf. recommended setting.

This engine has been great for me, probably got 25 flights on it, and haven't had a problem, running an A3 plug and 10% fuel. Now I switch to 15% fuel and I'm having these problems.

Ah, I see. Well I had the opposite proplem as you with that engine. Is it a different brand fuel as well? I had 15% os band X and couldn't get the thing to run worth crap, and was dead stick every flight. Switched to Cool Power 15% Heli fuel and it runs perfect now. Never adjust it and it never dies. Sounds like you already know how to adjust it so maybe try a different fuel.

Edit: My mistake. I thought you said you changed fuel. No clue where I got that idea from.

Is it possible you got some crap in your fuel line, and it's stuck in your high speed needle? That would lean the mix out, making adjustment impossible. Pull hi speed needle apart and clean....


Andy

I agree with a65l; sounds like there is something stuck in your fuel line somewhere. Remove the HS needle valve completely as well as the fuel line and blow out everything then rinse out with fresh fuel.

I see you changed from 10% to 15% nitro. Is the oil content the same ? You may need additional oil. The engine should not get "smoking hot". Another possibility would be a different plug - perhaps an OS #8.

As for the bubble in the line. You may have a piece of crud in the needle valve body. Disassemble the needle valve, clean in fresh fuel and reassemble. Pay particular attention to the "O-rings" on the remote needle valve. There have been several comments about air leaking in through them. If this is happening it would explain the bubble AND the lean run.

Switch back to 10% nitro and see if it runs okay. If not, then you know it's not the fuel and that there must be something else wrong (like the aforementioned crud in the needle). I was lucky enough to purchase a bottle of fuel that was bad. I had all sorts of trouble with the engine and changed everything I could think of. Finally I bought some different fuel and that cleared it right up. The fuel probably isn't the problem, but it doesn't hurt to check.

Kerry

Bad O ring on needle valve, Air in fuel line means that you are getting air past the O ring and not getting fuel from the tank, it will idle great but get hot and stall or quite at high RPM. Could cause damage to engine cylinder and piston.

Well I tried everything, and it just doesn't want to be nice to me with the 15%. I went back to the 10% and everything is fine now. I wonder if maybe the bottle was misslabeled and it's really 20 or 25% fuel.
I need to get a proper thermometer for engines.

Thanks for the help.