For you 250R engine diagnosticians

[fxnteeth]

I have a beautiful 86 250R with an 38mm Airstriker carb, no air box. Unifilter with outerwear. I live in Louisiana. The bike pulls great when short shifting. Once I get to 3/4 to full throttle, it sputters. We have main jetted from 120 to 180 with no real difference in performance. Perfect Plug chop at 165 through all 6 gears. V-force 3 reed cage and reeds (brand new). I replaced the stator and CDI. No problems there. It all tested normal. Newly rebuilt motor by Krank it. 110 octane vs. 93 octane no difference. The carb has been cleaned no difference. WTF!! What more can I do!!
Please help getting very frustrated.
Thank you
Jarrod

[portland250r]

did you try adjusting the fuel air mixture on the carb? with all the parts you got you might want to check up on everything. your carb may not work properley with some of the other parts you got.

[pablo]

I would try a stock carb and stock exhaust to insure the motor is running good.

Then change out the pipe and muffler. Lastly switch to the airstriker carb.

[RubberSalt]

The air strykers can be a pain in the but to tune in, but once you get it.. it's awesome. Now that 3/4 to full throttle is strictly main jet. Is it cutting out or is it bogging down? I find tuning in this order best; Pilot jet 1/4 throttle, main jet, wide open, 1/4 -3/4 needle position. Don't try to tune he needle first, once you change your main jet, the needle can be off a ton.

Buddy of mine is tuning in his 39mm airstryker for his polaris - Shop was out of 135 jets - the popular 1s lol

[Mosh]

I run a very similar set-up, except I have the air box with no lid and a K&N. Ported jug, VF3's FMF pipe.

Is your flywheel rusty?
And Have you checked if your carb slide is opening all the way? (I know simple but it does get overlooked)
If you can, I would run the airbox.
IMO you should at least be at the a 175 on the main with the needle in the middle position. That is where I am at 600ft above SL.

[atc007]

120 was waaaaaaayyy lean. Your plug could not have been happy there??? 180 you should be real close I would think. Throw a pig in there,200,,or over.Get it black rich on your plug after 3 or so miles of running,and lean down to brown/light black. Compression check it,takes a minute,you may have already scored the piston w that much octane and a 120. Just my .02.

[RIDE-RED 250r]

FWIW, Im running a bored over, stock cylinder (not ported), 38mm Airstryker, 1Dir reeds and cage, full FMF exhaust. Mine settled on a 195 main and Im at about 300ft.....My guess would be that you are probably still lean on the main. If I put a 180 in mine i would probably burn down if I hammered full throttle. Probably wouldnt rev out to begin with...