M@1

I got a chance to try this today and I found that when I spray WD40 onto the front bearing (between the flywheel and cranckcase, not sure whether thats the front bearing or not but I assume so) the engine cuts out almost instantly. Is this supposed to happen? I'm guessing not but I don't really understand what causes it to stall. Any ideas would be greatly appreciated.

I fairly sure the fuel tank does not leak as I have put my finger over the pressure pipe inlet and blown down the fuel line (with fuel in the tank) and the fuel does not bubble whereas when I take my finger off and blown through it, it bubbles I have looked at the carb and couldn't see anything obviously wrong with it. How would I go about checking the bearings for leaks? Also it was bought second hand so I can't really return it (it didn't have the problem the first few times I used it).

I've got a Thunder Tiger TS4N with the stock .12 engine and it's got a really annoying problem with air bubbles getting into the fuel pipe. I've set it to run really rich and it does so for about 50% of the time and the rest of the time it runs very lean. For example I will accelerate from a standstill and it will bog down and move with lots of smoke pouring out (as expected), I then stop, turn around and do the same and there will be no smoke at all and it will scream and sometimes cut out when it picks up speed. The engine gets very hot which I assume is as a result of it not getting enough fuel. I have checked over it countless time and have found nothing wrong with it, the pipes and tank make an air tight seal and nothing seams to be leaking or anything like that. One thing to note is that when I first noticed the problem I found that one of the engine head bolts had the thread stripped and fuel was leaking out of the top of the head. I tapped a new thread and put a new bolt in which has stopped fuel from leaking out but has not stopped the problem with the air in the pipe. Hopefully someone will be able help me, thanks for reading