I'm building a 1980 GSX250 E (I think) with my son. I need to get some carbs. I think the originals were twin mikuni bs30, and there's a couple of old sets on evilbay, but before I buy some.... Its going to be modified so there's no need to stay standard: is there a good upgrade to go for? ... that are cheap? thanks ps - if anyone has a spare set, and an exhaust going cheap, please let me know. There are many non model specific aftermarket carbs on e-bay.  Figure out which ones have the same size outlet.  They will be two separate carb, so you would need to run a one-into-two throttle cable like many of the old Suzuki two-stroke twin cylinders ran.  Non CV carbs should run well with inexpensive pod filters.  Get new rubber intake manifolds. Just my thoughts. There are many non model specific aftermarket carbs on e-bay.  Figure out which ones have the same size outlet.  They will be two separate carb, so you would need to run a one-into-two throttle cable like many of the old Suzuki two-stroke twin cylinders ran.  Non CV carbs should run well with inexpensive pod filters.  Get new rubber intake manifolds. Just my thoughts.