Difference? They are completely different. The needles and main jets *may* be interchangeable, but everything else is different. I would bet that the 28 carbs are *easier* to overbore since the bore is round, while the 21 carbs are an offset kind of oval bore. Even then, the needle-jet on the 28 is non-removeable so you cant get a boring device to go through without hitting it. _________________ Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS
We will be running a vortex electronic ignition that will talk to the tps and power-jets, so the mc28 carbs may be the go.
As for boring out the carbs, we can possibly bore up to the needle-jet from each side and then hand finish the rest.
What about the mc28's pgm system which apparently "opens solenoids at appropriate times which in turn control specific air passages into the carbs"(quoting a magazine article here).
Anyone got more info on this carb set-up for MC28's?
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