04 CR250 Falls flat on top, Need HELP ASAP!

[squidrider33]

I race motocross in A class so I know a little bit but this one is getting on my nerves. I have a 04 250 that I bought blown up in a box. I got a a hotrod complete crank, honda cylinder and head, and wiseco piston and rings. Carb is basically brand new, 400 main, 35 pilot everything else stock. fmf fatty and shorty silencer. power valves adjusted properly. Everything is visually perfect. BUT when try to rev out a gear the power just falls of, it hits hard out of a corner and on short bursts, just cant rev it out. Also bike loads up bad when I first start it up.

[Big Maico 393]

Originally Posted by squidrider33

I race motocross in A class so I know a little bit but this one is getting on my nerves. I have a 04 250 that I bought blown up in a box. I got a a hotrod complete crank, honda cylinder and head, and wiseco piston and rings. Carb is basically brand new, 400 main, 35 pilot everything else stock. fmf fatty and shorty silencer. power valves adjusted properly. Everything is visually perfect. BUT when try to rev out a gear the power just falls of, it hits hard out of a corner and on short bursts, just cant rev it out. Also bike loads up bad when I first start it up.

Sounds like the reeds might be starting to go bad, take them out & look for little cracks or if the end are starting to become brittle.

[AV8R]

First of let me say your my hero if you ride a 2 stroke in the A class!
I would look to the jetting if the reeds are good like big maico suggests. If the main is too rich it will cause a flat top end and it will not rev out properly. Loading up at idle is too rich on the slow/pilot jet. Try leaning it first with the air screw. If that can't clean it up then a smaller slow jet is in order. Check out the jetting sticky it helps a lot.

[squidrider33]

The Reeds are fine, its a brand new v-force reed block and reeds, but i checked anyway and they are good to go. Do you think it could be electrical, that it could just not be burning enough fuel wide open?

[AV8R]

that it could just not be burning enough fuel wide open?

Just the opposite I would say. Too much fuel at WOT. start leaning the main one step at a time after you get the slow jet worked out.

[jeh32772]

Have you checked the bike for air leaks in the motor. Air leaks always makes it hard to jet the bike right.