Ok finally got my short rod motor trx250r out since my hip replacement. Ran great putted around alot. Open it up get on the pipe and it would pull hard. Get where i can really go hit high end of 5th gear into 6th and it stutters like its off the pipe(aka power band) as though before it comes on the pipe rough and not smooth. 110 sunoco 30:1 belray MC1 oil, b8es ngk plug. Boysen reeds do have some age but rpm doesnt seem to be a factor since it doesnt do it in any other gear or free reving. Just annoying will run about 67mph in 6th stuttering. There should be alot more left.
high gear stutter
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Are the reeds chipped on the ends? Was the carb re-jetted with the reeds or any other Mods?
Have you tried turning the air screw?
I have a Super Mod'ed 400 EX now. But have ran many different bikes over the years (97 Banshee.- 98 CR 125 - 02 KTM 250 - 05 KFX 250 - 87 250R - 99 400 EX and a few other that I had that are not worth mentioning).
Jetting is the hardest thing to do, if you dont know what to do. Knowing the difference between Rich and Lean is Key..
Does it have a limiter on it?
Have you tried turning the air screw?
I have a Super Mod'ed 400 EX now. But have ran many different bikes over the years (97 Banshee.- 98 CR 125 - 02 KTM 250 - 05 KFX 250 - 87 250R - 99 400 EX and a few other that I had that are not worth mentioning).
Jetting is the hardest thing to do, if you dont know what to do. Knowing the difference between Rich and Lean is Key..
Does it have a limiter on it?
Sounds like it may be running rich. The main jet takes care of fueling at 3/4 to open throttle. 30:1 is a lot of oil, I'm running 50:1 w/Motul oil and 93 octane in my KTM 300.
Wide open any other gear is ok. So is free reving. I do need to check reeds. Would like to just get a set of vforce reeds and cage. I thought 30:1 was rich also but after some research other R owners run even in the 20s:1. A ex 250r pro racer set up my jetting and recommended the mix. He has a wall full of trophys to back himself up in his atv shop so i took his word for it. Ive run it that way for 8years now on the same rings (it ready for a rebuild). When he jetted it I had 18" tires on the back and went to 20 for occasional trail riding. First done the same thing before tire change so i wonder if its just gearing, somehow rpm not changiing fast enough in those gears.
Love to just go ahead and get ESRs $1500 330 powervalve kit from airbox to silencer if i had a pile of cash around
Giles
Burning Hunk
The first thing that comes to mind is --spark plug. Regardless of how new it is, change to a new one. Most high load engine miss is caused from ignition problem.
The simplest way to check jetting is to do the following test under problem conditions--
Under wide open throttle, Very slightly apply choke-starter jet---improvement would suggest a lean mixture.
While holding throttle at wide open position, slightly back off throttle--improvement suggest a rich mixture.
The simplest way to check jetting is to do the following test under problem conditions--
Under wide open throttle, Very slightly apply choke-starter jet---improvement would suggest a lean mixture.
While holding throttle at wide open position, slightly back off throttle--improvement suggest a rich mixture.
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