Ben French
CB750 New member
Ok so here's the problem: I bought a wreck of a cb750 (1981) as a project café bike. cylinder block has 900cc on the casting near the base where the gasket to the crank case is. The guy I bought it off said that the 750cc crank case was interchangeable with the original 750cc cylinder block and head and the 900cc cylinder block and head. He said that the cylinder block and head had been swapped with the 900 so that the engine id number still matched a 750cc and thus registration, insurance etc would be cheaper (not that I care if that is the case or not). The engine is a non-runner, so far I have began rebuilding the carbs and in the mean time have managed to get the engine cranking over and firing a couple of times with starter spray sprayed into the holes where the carbs were. My question is, is it actually possible to run the 750 block with the 900 cylinder? or am I going to spend a long time rebuilding the engine just to find out that the reason he sold it to me is because he realized that the two aren't compatible!! has anyone hear of this or done it before??