I just finished breaking in my new .15 engine and now it won't start. I just discovered the other needle. I think the mixture setting is what's giving me the problem. I know how to tune airplane engines. How do you tune car engines? Any help would be appreciated. It used to start real easy when it was cold, then after it warms up it would shut down. It's VERY rich. 2 1/2 turns from all the way in on one and 2 turns in from flush on the other. Won't start now. Still the original plug. Around 8 or so tanks through it so far. Thanks guys.

Try replacing the Glow Plug with a colder one. GOOD luck with that.
And yes I know, I used to have airplanes, and they're so much easier to tune!
O well, they're still fun.

At 8 tanks you can begin leaning it out. If it won't start, pull the plug, check it, turn the engine upside down so that if it is flooded it will drain. If it still won't start and it has flooded, you have to pull the plug again. This time lean out your LSN by about 1/8th turn. I assume your HSN is set at a breakin setting. If this is the case, LEan it out by about 1/4 turn. Watch the engine's temperatures carefully and don't drive too aggressively... Continue to lean it out and at about tank 10-12 begin som performance tuning.

It acts like it doesn't want to pump fuel from the gas tank to the carb. I cleaned out the carb, I cleaned out the muffler. What else to do? Thanks guys.

I forgot. When I prime it, it starts for a little bit then dies.

When I was taking the carb apart I noticed that on the idle adjustment and the (mixture at idle) screws had damaged o-ring seals on it, could this be causing a problem? the one on the mixture screw is almost totally gone.

I found out what was causing my problem. A huge air leak in the carb. I got an XTM engine .15 size. The seal for the idle adjustment screw, and both seal for the low end mixture adjustment needes to be replaced. Waiting on part I had to order. Wish me luck.

Eventualy theres always a reason for a refusing engine... even if its just a dumb silicone seal
glad you found your problem
good luck!

I take the high end throttle adjustment screw out, put my finger over that hole and put my finger over the intake to the carb. It should pull a bunch of gas into the carb at this point, right? It doesn't. I just have a problem with it not pulling gas into the carb. It runs fine otherwise.

Thats not quite how it works. Put the highend needle back in, adjust it to roughly the right setting, (rather ritch than a lean mixture) Take out the glow plug. Open carb WOT (wide open throttle). Now put your finger over the air intake. *Start* the engine (dont know if you are using pull start or external starter) with the plug out! It should draw alot of fuel in to the engine. Carefull with your eyes though!!! Fuel will be spraying out of the glowplug hole.
A very crude way to tell if the engine takes in fuel, but an effective way. IF it doesnt take in fuel dont keep trying to long, because of engine lubrication.