KZ650 Sleeper Build (831cc engine)

This is a ongoing project bike I first rebuilt in 2012. I bought the complete bike in bits for $200 and it has been my main street bike until 2021 when I removed the engine. The frame has now been converted to run a Z1 engine.





Its a early '77 B1 frame that has been converted to use '81 GPZ550 wheels/brakes/fork/swing arm. I bought it this way, it came with a '82 CSR engine, and it had been road raced at one point (drilled/wired)

The first 650 I bought in 1984 had been rebuilt by me right after I bought it. I built that engine up with a new 831cc MTC piston kit, self ported and modified big valve head, and GSXR750R flat slide carbs bored to 33mm.



This same bike went on to be drag raced after I stopped street riding in 1992.



The engine was retired in 1996 but the chassis is still a race bike. This original 831cc engine is what is in this street bike build (cases/pistons) The pistons were originally 13:1 but were cut down to around 11:1 compression. A new barrel was built with oversized liners.



A new 650 street head was built using 35/31 SS valves sunk back and ported to flow as much as a GPZ1100. Actual measured compression with this head is 9.9:1



Cams are .400" lift WebCam #189, and carbs vary from VM26 to RS34's. In sleeper mode it probably makes around 85 HP to the wheel, more with pipe/pods.





For most of its life it was running a MAC 4 into 2 megaphone exhaust and a air box (sleeper mode) but on occasion it has had a pipe and pods.



Currently the engine is together and sitting on a cart waiting till I get another frame built for it.