Ok guys I am stumped.
I just got a kfx80 it's a 2003. It starts right up and runs good till about half throttle. Then it Boggs down like it has a limiter on it. I will not hit the powerband. It has a new jug,piston ,rings. I burnt the exhaust out hoping that would help. It did a little . The fuel lines and vac line are hooked up correct.

 

Did you buy it with the new top end or did u put it on. If u installed did u put arrow on piston pointing toward exhaust and did u give it a break in period before giving it a lot of throttle

 

Yes the arrow is facing towards the exhaust, and he ran it just above idle for about 20 min

 

Clean the carb?

 

I going to go thru the carb again. Hopefully it will work.
Lt 80 what do you think the best mod is for trail riding .

 

I don't know what you want to do.
More speed/power? Handling?
Tons of info on here.

 

Prob handling and power

 

Wider is always better. You can make or buy stud extenders/spacers. The James Lucky front end extenders work well.
Power: Maybe my stage 2 motor.

 

Update. Cleaned the carb , ran a little better for about 5 min . Changed the plug ,sat it up on a block ran it with no load and it ran great, nice and crisp power band the whole 9 . And then it ran out of fuel fill her up and back to the same old running like crap. The guy I got it from said it did the same thing to him ran great right before it ran out of fuel ?

 

Could it poss be a reed valve prob ?