250R pops and sputters after 1/2 throttle?

[RUNMYTA]

My 89R for the last 2 rides would run great for the first 5-8 min and then start missing popping and sputtering past half throttle! What confuses me is that it will run like a beast for the first few minutes and then it will start running like junk. I think it might be the coil getting hot and breaking down. I don't think it is a carb problem because I just replaced the RAD valve and intake boot. Is there anyway to checkout the electrical system easily??? Thanks,MIKE

[jerry-89-250R]

got any friends with a R, switch the coil and cdi from your's, ride-em and see. don't know of any places that load test atv ign.

[beerock]

if it runs good for the first couple minutes then it sounds like it could be your jetting.

what color is the plug when you take it out?(try to look where the threads start, inside)

usually sputtering and popping is a lean condition.


what sparkplug are you running? you should be running a br8es.

dont fool with the electronics just yet.

Maybe your rad valve is leaking? did you use new intake gaskets?

[smith]

also swap out the stator with a buddys (if you have one with a 250r). Sounds to be the common problem with your description.

[Bean]

check the CDI wires and Stator wires, u mighta blown one of them out, or melted them togather or something, also u might be lean on the needle and main, what are u runnin?