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Hey i have a 1979 kz650 that needs a new engine. Anyone have suggestions on a faster engine that will bolt in or use very little mods. 750's, 900's and 1000's would be great. Thanks

Any 4 cylinder KZ750 engine will bolt right in. The 900 and1000 wil require frame modifications.

The 1980 and 1981 750 should be easiest to install. On later years Kawasaki changed the engine mounts somewhat and added rubber mounts. To install one of those engines some frame mods would be necessary.

Do you know any other engines other than kz? I wouldn't mind slight frame mods. I've heard gxr750, ninja 900?

Nope.
GPX750, ZXR750, GPZ750/900 water cooled will require major sugery.
Stick with Ed's advice. 1980-81 KZ750 E or L engine.
/Anders

I have 650 frame with 750 upgraded to 810 bigbore, alot of fun

Hopped up GPZ1100 engine into a KZ750 frame which is almost identical to the KZ650 frame.

Love to follow your project

Ariel96 wrote: Do you know any other engines other than kz? I wouldn't mind slight frame mods. I've heard gxr750, ninja 900?

Anything will fit into anything else if you have the skill.
Oilcooled GSXR 750 ,GSF 650/750, Bandit 600/650 are the easiest to fit ( Been there, Done that ) as they leave plenty of room in the frame but you still need to change all but one of the engine mounts and then fabricate exhausts and use most of the Suzuki wiring etc.
As this site is KZR i personally would either go for a bigger 750 /1000 kwak motor or just go buy another bike as that would probably end up cheaper.

zed1015 wrote: ............................. just go buy another bike as that would probably end up cheaper.

Exactly! Ed