KZ305AE vs. KZ305AE

Hey guys, I posted up pics of my new bike in the "newbie fourm." I got an '82 KZ305 CSR with the engine model KZ305AE... I also picked up a "parts" motor with model number KZ305AE. The parts motor appears to have a different head, and all black casing. I'm wondering if I got a KZ305AE out of a GPZ305 sportbike? What are the differences? Doesn't the GPZ305 make ~6ph more than the KZ? Any info is greatly appreciated.

Kawasaki used the same motor series in several different lines of bikes...e.g. the VIN KZ305AEXXXX series is the same basic motor for the KZ305A line, KZ305C line, and the EX305 (AKA GPz 305) line. Granted there are difference between the motors, but they are fundamentally the same. And yes, the GPz motor has 6 more HP than the LTD/CSR bike. Kawasaki did the same exact thing between contemporary 750 bikes with the KZ750 and ZX750 sharing the same basic motor platform (and engine VIN series).

In the series where various model lines used a shared engine line, there is no way to ID a motor based on VIN as to what model series it was installed into (Kawasaki apparently didn't keep track)...you must look at the physical appearance of the motor....i.e. if it looks like a GPz motor, then it probably is.

It sounds like you have a GPZ engine due to the black paint you described. One thing that could id it for sure would be the presence of an electronic ignition. The CSR's used a point ignition.

Yes... this is the "head" difference I was talking about. The head cover on the "parts" motor does not have the "points." I got the top end torn off the spare motor, and it all seems good... No burns, scars, and the cylinder cross-hatching is still good.

I'm 95% sure the spare motor is from an EX/GPZ. Which, if I'm correct, means that the extra 6hp probably comes from the camshaft, and higher compression pistons? I believe I read that the CSR has a 9.5:1 CR where the GPZ had a 9.7:1 CR. So do you guys think I should be able to swap the camshaft into the CSR head? The piston will most definitely be used on the CSR.