over heating

['blanshee'man]

i ran a 310 main jet last season with no problems when i put on my dyno port. After re-jetting back to a 310 after winter it still ran fine. i did my top end and broke it in correctly wit that same 310. Then i put a larger carb on that gave me issues so i went back to stock. It still ran great with the stock carb for about a day, then randomly it over heats and dies, and i cant start until it cools off. I had bad blow back so i got new reeds, they only cured the blow back. i put in a 330 main and it lasts a lil longer but it still is over heating. There is no way it should be that large right? My oil injection has not quit, i checked it.There are no air leaks icheck several times. Im running a dyno port exhaust, vf3 reeds, open airbox and a moose racing filter. The air/fuel screw is one and 1/2 turns out and my needle is on seat 3, but both have been all over the place trying to get it to run correctly, ive spent 3 weeks trying to get it run and im out of ideas. So Any ideas would be great. thanks

 

[Banzai]

I had the same sort of problem with a chainsaw a couple years ago.

Ran fine in the shop, but when I took it out to cut wood I'd make a few cuts and then it would quickly lose power and die.

I checked the carb about nine times, never found anything. So i tore the motor down.
The bore was egg/oval shaped it was so worn.

I would suggest pulling your jug and checking the bore at top and bottom. it might be out so bad that when the motor heats up the cylinder grows enough that the piston clearance gets too big, and that makes too much blow by.

Too much blow by would make it heat up real fast and then lose power.
Just a thought.

 

['blanshee'man]

Thanks, ya i thought that too but i just had the cylender honed and checked for round when i did my top end, it was fine then and ive had very lttle ride time on it since then. But i will check it again i had a few of my ridin buddies say it aswell. i also was gunna check compression before it warmed up and after but i didnt have my compression tester.

 

[89custom]

have you dont a leakdown test? it could be a bad air leak.

 

['blanshee'man]

i sprayed every gasket and opening with wd and havent found one. Or are you talking about somthing else?