engine transplant?

My son brought home a 1980 kz750 this summer as his latest project bike. Well now he's off to college so it's all mine to tinker with when I have the time. We learned very little of the history of this bike from the previous owner, and as I dig into it I now think that the engine is a transplant. The frame is ser.no. KZ750H004441 which according to Haynes manual makes it a US model H1(LTD). The engine ser.no. is KZ750EE007958. That make me think that the engine is from a different bike. Can anyone confirm that for me? If so, are there any differences between the two I need to know about? The carbs are Mikunis, what model I don't know. Would those carbs have been original on either of these (kz750H or kz750E) bikes? Then the carbs have individual K&N pleated filters. I'm pretty sure those weren't original either.

Not sure about the 750's but on the big bikes the frame (vin) number and the engine number don't match. I'm sure someone on here knows where to look up engine numbers and will chime in.

On the 650;s most if not all have different numbers and the air filters are NOT stock.

The 750 (4) series of bikes E, R, H, even the ZX750 series all had KZ750EE00XXXX motor series in them...there is no clear way to differentiate which motors went into which model bikes. I strongly suspect your bike has the original motor in it.

I don't believe the ZX750's (83-85 GPz750) had engine serial numbers that started with KZ750, I think they start with ZX750.

I'll try to remember to take a look tomorrow to verify this.

All the rest did indeed start with KZ750EE though

Zedder lists different engine serial numbers for the E models vs the H models, so you can probably determine what model the engine originally powered by seeing what range your engine serial number fits in.


I just took a look at the Zedder Kawasaki specs page and the KZ750H is no longer listed there, Just the 750 triple, 750 twin, and 750E.

I appreciate the input and comments. I didn't expect the engine/frame numbers to match, it was the KZ750EE in the engine serial no. that threw me off. I would have thought it would be KZ750HE if it were the original engine.