I just finished rebuilding the top end on my 99 400 (piston and rings). As I was installing the carb I noticed that the cylinder side of the carb slide is plastic. This has a crack in it toward the bottom. Anyone else have this problem before? Would this cause a some backfiring when I chop the throttle at speed? I have ordered a new one and plan to install ASAP. $75 for that little piece of plastic! The bike is totally stock, and yes I did adjust the air screw long ago and it rarely backfired untill later this year. Thanks in advance!