Quad 50cc (minarelli horizontal) overheating issue
I am working on a SMC quad wich has a minarelli horizontal replica engine in it. First it was not running at all. I decided to replace the piston and cilinder. I bought a 50cc kit because that was on the side of the original cylinder. But when i took it apart the original cylinder and piston where way bigger than the 50cc kit i bought. It looked like 70/80cc. I had bought the kit already so i put it in. After messing with carberatuers for a while because it wasent running great and kept dying after a couple of seconds i got it running. Turned out the jet in the original carb was too big for this cylinder.
But now i have a problem. It keeps running really hot. And it has already died 2 times while i was riding it. One of the two times it became stuck. Had to kick it really hard to get it loose again.
What i have tried is changing the mixture because it could be to lean. But i have changed the jet already from 54 to 64 and also to 75. With 64 it runs but not stationary and with 75 it will start but die after a couple of seconds. The original carb had a 74 jet inside it
I have read the spark plug and it is looking very nice coffee brown with no white spots in it.
Can someone help me?