Newish motor, run-in and flown ~6 times over the summer (I don't fly very often). Bought from Just Engines. Mounted in my 4*40 turning a 12x6 APC prop. Runs fine but does not want to stop! Even placing my finger over the carb intake does not stop it - need to pull the fuel line.

Thinking it might be an air leak from around the carb. seat, I removed the carb. and replaced with a bead of silicone around the base/seat area. No difference.

I've seen some posts where people refer to the front bearing seal. Not being an expert with engines, how do I confirm this as a possibility? And then how do I go about replacing this seal?

I guess I'm learning the drawback of ordering from Just Engines. I suppose they'd take care of it if I mailed the engine back to them, but the hassle involved in multiple international mailings is giving me pause.

Thanks for any help,

Ram
(newbie around here)

Sometimes the carb barrel screw on top of the carb sucks a little air. You may need to put some RTV silicone on it . Just make sure you clean the screw and tapped hole in the carb to get any oil or fuel off of them before you put the RTV on. The idle needle may also need this treatment. Once the RTV sets up on the idle needle threads, you can still adjust it. Just make sure to keep the RTV off the tip of the needle when you thread it back in. Check to make certain the carb barrel goes just PAST closed on the carb. If it's even a sliver open, it'll suck air. Try leaning the low end out as much as you can get it, but still maintaining a good transition.
Your front bearing is not sucking air...if it were, the engine wouldn't run at all. The rubber seal on that bearing is there only to protect the bearing from dust and dirt..nothing more. Hope this helps.

Thanks AtomHeartMother, I will try your suggestions.

Ram

It is not your front bearing that is causing this. The cinch bolt that holds the carb in on these has a tendancy to work loose but sounds like you have already worked with that. Have you checked the bolts on the backplate ?. Loose bolts here will cause the problem you mention.