I have a 87 F1 in a micro sprint and the local dirt track has allowed a open motor rule for 2007. At the current time the motor is stock and the only mod. is the top of the air box was cut off to fit in the car and it has been switched over to methonal alcohol, with the main jets drilled out .125 and the idle jets out to .037. My question is, can anybody tell me how much bigger of flat slide carb I can run on the motor. The only thing that will be changed is the timing is going to be set around 38-40 deg. BTDC due to the alky. I'm trying to get a little more out of the motor since its running against f3's, f4's and R6's but dont want to spend a bunch since I'm just having fun. Thanks in advance.

 

33mm is oem, 34mm is about as big as the intake track opening will take.