CR250 running poorly

[lineskier24]

I have a 99' cr250 that has been running great since i bought it 3 years ago. it didnt start at the beginning of the season so i ripped it apart cleaned it and put new seals on the top end. it started the other day pretty easily, however it smokes like a SOB and it doesnt sound like its running very smoothly, to top it off it only runs under constant throttle response. Dont no wats my next step in getting it to run like it used to.??

 

[IndyMX]

Did you clean and blow out all the jets in your carb?

 

[CarnageZ28]

Check your gear oil. If its low, its possible the crank seals are leaking and you are burning transmission fluid that has leaked past the crank seals and into the crank case where they are drawn into the cylinder, and burning ...

What color smoke? Smell? Is your antifreeze low? Do a compression check as well! You need like at least 100# to start kicking it.

 

[dirt bike dave]

When you put the cylinder back on, it is possible the little fork that operates the powervalve was not positioned properly, and your power valve is either not opening or stuck open.

This is an easy mistake to make on the '92 - '01 CR250 motors. You need to really make sure that the little fork and shaft at the bottom right front of the cyliner lines up exactly right. If you are not aligned properly, you will have to remove the cylinder again to get it right.

There is a powervalve inspection cap on one side of the cylinder (left side, I think). You can remove that cap, and start the motor. Rev it in neuetral. When the revs build, the powervalve shaft should turn 90 degrees from closed to open.

Also, the only time my old '99 CR250 had trouble starting, it is because the reeds were bad. Even a slight warp or crack can make it very difficult to cold start.

But sounds like you have a new problem.

 

[lineskier24]

The smoke is a very light grey. the antifreeze was just drained and refilled along with the gear oil.

i did have to disassembe the power valve the other day. i had a hard time putting it back together, but i thought i had it correct. i did make sure the connection at the bottom of the cylinder was aligned correctly. it could be the reeds cuz they werent in perfect condition, although im skeptical that is the why it sounds the way it does.

 

[IndyMX]

Fix the reeds before trying to diagnose..

They will only make another problem that much harder to figure out.