96 kx 250 spluttering?

[Shane3004]

wel lads have a 96 kx250, just done a full rebuild, 2day was the first test run, was driving it half throttle for most of the day, at the end i was giving it a bit more, but i noticed dat when i hit the power band it spluttered a bit as if the revs were braking down, i messed around with the air/fuel screw, which made a bit of differences, opened bout half to 1 full turn, but was still missing a bit when hitting powerband, 1st 2nd are worst then as u get up threw gears not as bad, bike was grand before rebuild, what you,s thinks, timming, jetting, any suggesting? 

[sandblaster]

I'd pull the plug and take a look first to see what can be seen...
I would then check my kill switch by disconnecting it and running it.
Next, I would check the reed valve to make sure all the petals are in full contact when closed with no cracks or pieces missing.
If no problems are found there I would check the ohm specs of you stator, cdi, and coil.
Let us know what you try... And the results..

[Shane3004]

i,l try all dat 2moro, theres a new plug, plug cap and air filter and the reeds were all cleaned and they look good, no cracks or anything, the carb has a 42 slow jet, 162 main jet, and second notch on neddle, it dont have a powerjet, the engine got a full rebuild and it has a full pro cuircuit exhaust, i,l try what ya said first anyway, its just weird cause the bike was goin fine before the rebuild, it is revving grand, just when ya get up in the high revs it brakes down, its like she,s still cold thanks anyway, i,l let ya no

[Shane3004]

Got the kx sorted, put in the old plug and off she went, back wheel the whole way, happy days  , turns out the new plug was faulty, thanks for your input sandblaster!

[sandblaster]

No problem.
Always check the cheap and easy things first