I have a 1989 LT80 that I just put a new top end on. I also took the exhaust restrictor off and the card restrictor was already long gone. It will start up great bit bogs and dies at half to full throttle. At first I thought it needed a larger main after taking out the restrictors but that made it worse. I currently have a 87.5 in it and it is a little better but will still bog if you go full throttle right away but if you was into it you can get it up to full throttle. The part that has me stumped is if you take off the air cleaner and elbow, it runs great. If you leave the air cleaner off but just put the elbow in it will bog, and the elbow is completely clean. I am getting to my wits end with this ting and cannot figure it out. I have checked for leaks with carb cleaner but cannot find any. Any suggestions?

 

I did forget to add that it was just an ebay top end kit. Could that be the problem? I just can’t understand why that would cause a rich like condition. Also it has a new air filter. Any help is greatly appreciated.

 

Have you cleaned the carb?

 

I figured it out. The head gasket was leaking. I haven’t had time to tear it apart yet and see if it is just the gasket or if my head is warped. Thanks for the response.

 

IMO, it's the china cylinder studs stretching. They are terrible.