Hi,
My brother bought a 1991 KX250, but there is a problem, it wont hit the powerband, the power infact seems to drop off as it attemps to reach it.

We did a full rebuild, piston, crank etc, and the issue is still there. We are thinking its either the card jets or the reed valves, any other suggestions?

Or has anyone had a problem like this before?

Thanks,
Chris

 

what rpm is droping off at?

 

Not sure, As theres no tacho on the bike.

 

Does the bike have a power valve,when you say card jets do you mean Carb jets, maybe, what else does the bike have done to it, have you cleaned the carb, id put my money on the PV if the unit has one., what NS was making remarks towards was could you be a little bit clearer when the power drops off, ie, 5th gear, last 1/4 of the throttle ,

 

More info ChrisBoom. How did the plug look? Welcome to the forums.