i have a 87 lt 250 quadracer with a stock bore.one of the washers on the piston pin broke and messed up my engine. i had it resleeved, new piston and crank rebuilt along with new crank bearing and seal. the air screw on the side of the carb was missing and it would idle fast before. I replaced the screw and it now runs ok on the top end but won't idle and has little power on the bottom end. i haved cleaned the carb twice. it seems to run better with the screw out. i had to turn the idle screw in all the way. the timing marks are alighned. the gas is fresh, plug is new.would the power valve have anything to do with it. i know it was taken out and cleaned when it was resleeved.. please keep in mind that this has never had anything done to the motor before and is used for mostly trail riding.. i would be greatful for any ideas and tips.
Did you have more bottem end power before? There could be a compression leak after reassembly. If there was any change in displacement you may have to rejet it by changing the air/fuel mixture. There is ussually a little screw on the side of the carbuerator. Increasing idle screw and rejetting should help your quad idle better. Let me know how you make out.