I have a 93 650SX which we have rebuilt the motor on, and in the process lost the original carb. After looking around I purchased a used carb and could never get it running... It would start but every time I gave it throttle it would go BWAA BWAA. After getting frustrated enough to chuck it in the trash I purchased a mikuni SBN-44 carb. Tuned it with original adjustment screw settings and it worked great. Took it to the lake, did a little fine tuning, rode it for about an hour, and left. Now I can't find my adjustment screw settings on carb or online, and it is doing the same thing it did in the first place, bwaa bwaa bwaaa lol.... I've about given up hope, but that ski is my favorite thing I own. Does anyone have any clue what could be causing this?? Or what a pretty accurate screw setting would be on that carb? BTW ski was bored out to around a 670 is what they said? I've though maybe it could be my primer creating a weird vacuum in there?? Thanks, I'd appreciate any help from this long, boring post.