Midrange Stutter

[Honda 250r 001]

Now that I've got my cooling issue figured out, I'm on to tuning now.
My 250r has had a midrange stutter for quite a while, I can only notice it when I'm riding down the roads in higher gears. I lug it a little in a high gear then just pin it and it takes off pretty good with no bog or hesitation, but just before it hits the power band it stutters and will misfire and "4-stroke", If i keep holding the throttle wide open, it will keep stuttering it for approx. 3-5 seconds then it gets into the power band and takes off, however if I let up on the throttle just a tad when its stuttering it takes off right away. What does this mean? My plug is a darkish brown, not black or tan. Should I try down on the main or change the needle position? Maybe a different needle all together? Also, I have a number 7 slide in my 39 PWK. Could this have something to do with it?

I've asked this question before, but my motor was running hot and i had an air leak so I figured starting fresh would be best.
Thanks guys.
Will.

[205dke187]

sounds like it may be just a tad rich on the main jet side..... not sure though

[Honda 250r 001]

Even though the plug is milk chocolate color you think it could be rich?

[205dke187]

i run my stuff a little on the lean side probably but a perfect plug should be a little lighter colored than milk chocolate. and it could have something to do with the reeds. but i would bring the main jet down 1 size and try that

[Grande Huevos]

you want your plug to be a light brown color almost carmel colored. It sounds like your fat on the main jet since you say it sputters at full throttle then cleans out when you let off a bit. I would would drop it a size and go ride it for a bit and see what happens. I wouldnt worry to much about the color of that plug unless you pull it out and its dry and white looking. You might end up dropping it a couple sizes before you get what your looking for.
Also when jetting dont worry about how many rpms you are pushing. When you notice a sputter pay attention to where your throttle position is, because it doesnt matter if it sputters at 1000 rpms or 8000 if you have the throttle wide open then its on the main jet

[205dke187]

yeah what he said....

[Honda 250r 001]

Alright, thanks guys, I went out and dropped the main from a 178 to a 172, it got better but didnt completely stop. Now that ive read this im gonna go drop to a 168 and hopefully it will go completely away.

My jetting currently is
172 (soon to be 168)
DGH on the 2 from bottom clip
55 Pilot
Stock cylinder on race fuel with MX porting

Now I have another question guys. Once again riding on the roads around my house. When Im in higher gears, and im coasting down,throttle completely closed, with the engine still hooked to the ground, as it gets near idle idle it starts firing before it gets to actual idle. It only fires occasionally, kinda, Put, put put, sound. Whats causing this? I sat and messed with the pilot for an hour or so and couldnt seem to fix it. Would this be too rich or lean on the pilot jet?

Thanks.
Will

[265 sleeper]

I had the same problem when tuning in my 310 I could get perfect red brown tint . Tryed all sort of jets I started to get to 168 and that I know was lean for my area at the temp . Tryed pilot 42 that's to lean from my experience of tuning a R stock motors up north call for that my bike not stock . I brought it well my friend bobizzle brought it to a known R builder in my area to see if he could figure it out I was fed up . I never let someone else touch my bikes never . Well he rode it and came back told my friend to use a carb he had that's known to be good I had tryed 2 different carb that worked for me before . Well the least to say it worked his carb hit the spot . All I had to do was retune she was set . So moral of the story is check your carb

[Honda 250r 001]

I switched my main jet down to a 168 and it didnt help any. The stutter was still there. Im puzzled. I only have another stock carb. Do you guys think its carb related? Or spark related? Maybe ill pick up another carb and try that.

[265 sleeper]

My was a mid range sputter perfect bottom great top would only sputter mid no matter what tuning I did always there . So the carb was my problem

[Honda 250r 001]

did it sputter at midrange RPM but with the throttle wide open?

[265 sleeper]

Sometimes but not all the time

[C41Xracer]

did you try dropping the needle?

[Honda 250r 001]

Ive tried raising it one notch, didnt help. i didnt try lowering it.

[mcboomport]

If it is clearing up at the top.. it sounds like you are too rich on the needle, not the main.

[Honda 250r 001]

Originally posted by mcboomport
If it is clearing up at the top.. it sounds like you are too rich on the needle, not the main.

Even with the throttle at 100% open position? With the motor running in midrange area?

[mcboomport]

Yes.. If it is only doing it for a few seconds as you say, the carb is clearing itself out when you are 100% full throttle, but it could be recovering from too much fuel from the needle position. I have to adjust my needle everytime I ride my bike based on temperature because it does what you are explaining.