at about quarter trottle my motor hesitates. How can I test this area of trottle. Should I clean the plug and run it at quarter trottle then look at it. Any suggestion if it is rich or lean.

 

ok no one else has taken a guess so i'll hit it...

i think 0 to 1/2 throttle is controlled by primarily the pilot jet, with some control by the main as well. i would submit to you that a quarter throttle stumble might indicate that the pilot jet size is too small. try bumping up a couple of steps and see what happens. it's not much more difficult than swapping a main jet.

 

If the pilot change doesn't help then you could also try moving the clip on the needle (up for leaner and down for richer). I'd drop the needle a notch and see what happens then.

 

bigmanm,
First of all let me correct you on one thing before anyone makes a cute remark to you...the word is THROTTLE (with an H). That said, when you say it hesitates, do you mean at a steady throttle or when you get on the gas? Also the pilot jet operates basically at idle to 1/4 throttle, the needle jet operates at 1/4 to 3/4 throttle, & the main at 3/4 to full throttle. As you can see, your problem is right at the threshold between the pilot jet and the needle jet. I would suggest that you RAISE the needle to the 4th position (the positions are numbered 1 thru 5, with 1 being the top position on your needle). This will fatten up your mix in the 1/4 to 3/4 part of your band. Keep in mind that these various jets have a certain amount of overlap, especially at thresholds like yours, so you'll need to test ride at the rpms where you're having the problem; and yes, using a new or clean plug when doing so would help so long as you don't run at any other part of the band before reading.

 

It occurs when i slowly push the gas in. It will hesitate then continue on normally. The needle jet is all the way to the top. When i put it down more it gets worse. All the signs show that it is to lean except the plug. Maybe that is because I always run at full throttle. I think I am going to buy 2 sizes smaller pilot and 2 sizes larger. And then see which make is better. I am leaning toward the larger ones because I just recently took off my air box. I rejetted the main. But What i can't figure out is why it gets worse when i make it richer by lowering the needle clip when taking the air box off made it leaner. I can't figure this out.

 

You may want to try a diffrent needle or even better get a DynaJet Kit.

 

if you allready rejetted then you went too big and the engine is running rich.put the stock jet back in and lower the c-clip 1 notch from where it was stock

 

Well before you even mess with the carb, clean your air filter and then see if the problem is still there. Don't re-jet for a dirty air filter

CT250R