Still having problems with low end missing

[rtcc]

Ok guys, this has been going on for some time now. On really hot days after I have been riding for about 15 to 20 minutes I start getting a really serious low and mid range spuddering.

 

Before this though I swear it runs amazing. Runs perfect. I really feel my jetting is spot on. I am going to do a plug chop the next time I am out though. Needle is middle clip.

 

(I leaned the jetting out on the screws and needles, but reading the plugs it seemed it was too lean so I put it back.)

 

When it starts to do it I will stop and let it sit for 10 minutes or so and then it will run fine again for awhile until about 10 minutes down the trail.

 

Im getting frustrated cause I have replaced most of everything. I have a new stator in, new (used) coil, changed plug caps. I even pulled the timing back to stock.

 

I then decided it was the cooling system, changed out all fluids to water and water wetter and got an aluminum impeller. It has improved slightly but still does it.

 

What stumps me is that the radiotor is not boiling over or anything, there hasnt been any water come out the over flow tube.

 

So what else is there that could be getting hot? Could the CDI be going out? I really feel like it is electrical now because Im not boiling over coolant.

 

Any help is appreciated guys, cause I dont even like to take it out cause Im affraid something is going to melt down on me.

 

 

thanks

[mercury65]

it still could be jeting to be shure its not, take a new set of plugs with you and when it starts to do it put in the new plugs in and ride it some more, but do not go WOT(no power band) then stop and check ur plugs. i had a same trouble with my sons 250 i was jut a tad fat at wot but at 1/2 throtle it was loading up. we have to stay a tad fat here becaue temps can change 40 dagrees from morning to mid day, and back to dusk. jetting is never on the money were i live. but when the temps drop they run great. yesterday 97, this morn right now 56. so now if one of my bikes are not running right its just to hot out.

[rtcc]

ok thanks, I will have to try that. I am gonna do plug chop as well. The top end feels so good though, it doesnt spudder out and pulls really hard all the way through, but it makes since what you are saying. Hopefully that is it. I will try backing off the mains one size as well.

[fatcracker76]

a failing cdi also acts the same when it heats up. next time it acts up try pouring water on your cdi and see if it's better, if so r2 cdi.