help with new BBk ---- please!

[sc00ter]

To rich would be my guess. Do a plug chop (Moped Army has a great how-to) and see what color it is. Compression test would be next. Find out what ballpark your compression is supposed to be. You can "borrow/rent" a compression tester from a better auto parts store. They love to leak during testing so make sure all connections are snug. Soapy water is your friend. The original compression reading would have been you data point, but to late for that. Its out there somewhere on the Web. You checked the valve clearance and made sure the timing was correct so Im not thinking that. If it was sudden (the fog affect) you could have a bad float or the choke got stuck, but not really thinking choke. If it was sudden you may have jumped a tooth? Does the bbk use the same spark plug heat range as original cylinder? Same reach spark plug? Check if the spark plug gap is correct also. Thats all I can think of for now off the top of my head.