hi just got my son an old lt50 bit of a wreck but it runs ive got a problem
if u push throttle lever to fast the engine loses power it goes ok when starting slowly but if u try to go faster it slows down the same we have cleaned the carp
i had a thought it might need lead in the petrol can anyone help me atall
thanks mark

 

clean air filter?did you clean jets while in the carb?

 

sounds like the carb like qwoder stated. did you clean all of the ports out on the jets? you need to completely disassemble, let it soak, and (i use piano wire) clean all of the jets and ports out. check float level, make sure intake isn't leaking.

 

I agree, it sound like a plugged jet.
If not, do a compression test.

 

make sure it has an air filter on it. most people who had these atvs got rid of air filter. they run better with one