webby7

Hi don't know if this is going to help but I had the exactly the same problem with B12 Kat, I tried new coils, new CDI, new set of carbs, Compression tested, Valve timing, in the end I solved the problem, it was the float heights even thou they were set correctly the B12 engine sits at a different angle in the Kat frame slightly lent more forward so not getting enough fuel. played with the standard carbs for weeks got it running pretty good but not 100% so tried a set RS38 carbs. problem solved.

Hi on my B12 im runing gsxr 750 cams and rs38 - with 140 mains and needle 3rd from top should be a good starting point, runs great, best to start rich and go from their.