I just bought the TBBK and set it in my 50 yesterday and for some reason it wont run for shit when i use the big carb it came with.. but when i set the stock carb on it ran fine!? it has to be a problem with the carb, any one have this problem?
Sounds like timing to me as said above by someone. I know on mine i had the same problem and it turned out that the timing wasnt right even though I had it set right with little t lined up and the little hash mark and o right. I had to figit with it a couple times before it would run right.
I had a simaler problem awhile back and it was as simple as the overflow tube was pinched on the cylinder.Man it popping and backfiring like crazy.However I do agree it does sounds like the timing is off though.
Take the carb apart and check it over. I just reread your first post and realized that you said it ran with the stock carb on. So take the new one and just take it apart and go through making sure everything is clean and together right and that none of the hoses are pinched when you put it on or anything. If none of that works, shoot Mike a email at TrailBikes and we will do everything he can to help you.