I recently had a buddy give me a 87 warrior 350,the bike ran awsome in the winter then i took it out first thing this summer and it idles great and revs nice, as long as you stay at the top of each gear it's ok, but then it bogs out for a few seconds until you either get barely on the clutch or downshift, it backfired a few times and blew a crack in the muffler. then i cleaned the carb and flushed the tank and changed the filters in the petcock and the plug..all to have the same bog problem without the backfire. everyone is telling me it's a valve issue and i'm hoping not since i know nothing about valve adjustment or replacement.i've also heard a few other things that it could be just as simple as carb adjustment,would it be to much fuel or air,i have a compression tester but no damn idea how to use it, should i bother or just go with the fuel air mix screw, also inside the mikuni carb when i opened the side cover there is a pin that at high throttle looks like it gets poused down by a white plastic lever could i have re-installed that backwards or something??