Tune your idle screw.

idlebar plugs were introduced when motors were being mounted inverted. it shields the element from the cold splash of fuel that comes into the cylinder. some engines do require an idle bar plug to run and it doesn't hurt any of them that i know of. the only thing it says on my Magnum xls paperwork is to run a hot plug. doesn't say idlebar or not, it runs just fine with a fox gold series plug in it. thing is with this and everything about this hobby, you will find people who use them and those that don't. go ask somebody a question about castor oil in you fuel and see how many answers you get!!
just do what you can to get it in the air!


john

Except it could be an indication that the head is leaking, which would give the exact problems he is having. Have you ever tightened your head screws?

I agree with the possible loose or misfitted head. Try removing it and cleaning it up and then retorque the screws down evenly just like you would put on a tire. Also run a smaller pitched prop. I've had 2 FP's and 2 LA's and they are pretty similar other than the remote needle valve setup seems to suck on inverted installations. I really wish they made the LA's carb adaptable to direct needle or remote. Anyway, try a 11x5 or 11x4 or a 10x5. If its a trainer you'll love the extra torque for takeoffs, and the higher rev's will help your idle issue because the engine will be running faster while moving less air and the lower pitch even act as a brake when you throttle down. Also are you running a inline filter on the plane? If not this could help. I have heard this can help reduce bubbles in the fuel line. If you do a search on LA's you'll find many people have to drill the air bleed hole larger. I just finished breaking in my .40 LA and didn't need to at all. My high speed needle is about 1 1/4 turnes out and the low speed I really didn't have to touch from stock. This is where a tach comes in. You really need one to tell what's going on and to give some real number. Mine will idle around 2500 and a little lower but really this just sounds much lower than any of my other engines. I haven't tached there idles but I can't imagine needing a idle lower than 2500. With a low pitch prop your plane won't be moving anyway at that rpm. While you are checking things I have read that sometimes the backplate screws also come loose. It might not be a bad idea to pull the backplate and head and use some locktite on the screws and crank them back in. A loose backplate could also cause problems. It may have been mentioned but check the carb hold downs for leaks. You can pull the carb and put a THIN layer of standard RTV silicone gasket maker around the carb and insert it and lock it down. Everyone else is right though. If you still have problems get someone experienced to look at it. Pull it off the plane and let someone bench test it for you. Even on the bench you can tell alot about a engine. Its frustrating to keep having problems with a engine and not being able to enjoy the hobby. All manufacturers have problems. I have owned many engines that I read posts on that are called crap or unreliable and on my planes they are some of the most reliable engines. Everything from LA's, Mecoas, Magnums, ect. Really they are all the same in the respect that the break in is the most important time and it only takes a couple of runs too lean to destroy any chance of having a reliable engine. If you are going to error in your settings always error on the rich side. By the way after 3 8oz tanks of fuel with a 10x5 and 15% wildcat my new os 40LA is taching at 13,000 rpm. Get / borrow a tach and see if you are in the ballpark.

Hey, I know I'm a little late here, but have you managed to find workable solutions to your engine woes yet?