750 engine in 650

My future father in law has two bikes. One is a 78 kz650D the other is a 79 kz750. Neither bike was running as of the first of this month. I have gotten the 650 running and in great order. Working on aesthetics with it now. Soon after starting this project I found the 750 disassembled. The frame is outside under a covered area and the engine is inside. I would need to locate all of the parts to rebuild which eventually WILL happen.

My question is.. Will the 750 engine fit on the 650? If so how much of an improvement will this make. The engine is black and I could rebuilt it into the original frame or remove the 650 engine and put the 750 in. What do you think? Worth it?

yes the cases for all four cylinder kz/ltd/csr 750's will fit in the kz650 frame and bolt up....there is a change to the stator that needs to be done but others here will know more...i think you need to put the stator from the 650 onto the 750 motor after switching....it makes a fun easy boost in power and also gives you a back up engine for later....imo...fix the 650 until it is all legal and ride it while you work all the bikes worn or loose stuff out...then later mess with the motor swap...funner to have running bike to ride before making it a project imo...

many years ago we put a ltd750 engine in a really clean looking sr650 and had a fun little bike the would pop wheelies by just punching it .....we did the swap because the 650 engine was broke and both bikes were cheap so we had beater 750 with a good motor to donor.....it was great bike after the switch

The 1979 KZ750 is a 2-cylinder motor so no, it will not bolt up into a KZ650 frame. As trianglelaguna mentioned, the 4-cylinder motors will fit the KZ650 frame, but there were no 4-cylinder KZ750 models built in 1979. On the bright side - the 2-cylinder KZ750 motor does not have as much pep as the KZ650 so you are better off keeping the 650 motor; although the 4-cylinder KZ750 motor did have more punch. Ed

Thanks trianglelaguna and Ed for another helpful post. I really thought that it was a 4 Cylinder. I Will look again. The possibility that I am wrong on either point is pretty high. I took a nice blow to the head yesterday when a ceiling tile fell on me at my desk.

I do agree that having. Working bike and a project is probably better. Rode to work this morning. Was amazing

I will probably finish polishing the engine and then start cleaning and rebuilding the other bike. Probably easier disassembled anyway.

It is a 1980 kz750E.

That is a 4-cylinder model, so the engine will fit in the KZ650 frame. If they were mine I would keep the engines in the same frames they came in and restore both bikes separately. That way you can ride the KZ650 while you restore the 750. When they are both finished you can decide which one you like best and if you only want one bike you can sell the other. Ed

650ed wrote: That is a 4-cylinder model, so the engine will fit in the KZ650 frame. If they were mine I would keep the engines in the same frames they came in and restore both bikes separately. That way you can ride the KZ650 while you restore the 750. When they are both finished you can decide which one you like best and if you only want one bike you can sell the other. Ed

+1 on Ed's input

Sound like a plan

the 750 is the one to put an 810 cc kit in :evil: !!!!!

kzzone.com/pistons.html

just sayin :whistle: .

leon

yeah...killer that the 650 runs...keep on fixing and tinkering with stuff on that one till you are all smiles every ride....one running bike beats three or four project bikes any day

the 650 is a strong everyday rider that will do anything you want...tour....carve a road....two up date rides....great bike,....score...on the 750, 1980 was a killer year for that bike too