I'm helping my buddy fix his yzf 250. it only idles with the choke on. we checked the valves cleaned out all the jets and and especially the (pilot jet) when reassembling the carb I noticed what looked like a crack in the lower carb. the bike was pre owned (craigslist). im a lil unfamiliar with Yamaha's pleas help me. I GOT SOME PICS I POSTED WITH THIS FORM.