1978 KZ650 Bike Build

All the bikes are finally cleaned up and put to bed for the winter. The last week or two have been pretty boring so I started looking for a project. Today I found a 1978 KZ650 for sale....well just the frame, engine, carbs and a couple of the electrical bits. This will be a challenge, but it's not intended to be a restoration. I have some spare Z1 stuff that will probably fit....wheels, gauges, lights, etc. So it will be a bit of a frankenbike. The goal is to get it back to reasonable condition over the next year or so.

My first problem is the frame. Someone at some point had the bright idea to make a bobber out of the bike, so they cut the frame just behind the back seat hinge. There are a few tail pieces available on ebay and I want to buy one but I want the best one available. There are '78, '79. and '80 sections available. My question is whether they are all the same or do I need to stick to '78 only?

You can see where the frame was cut, just behind the rear seat hinge. I guess the plan was to build a hardtail because the shock mounts are missing.



The engine was supposedly rebuilt by the PO, who apparently is a diesel mechanic with access to a full shop. The engine is still pretty dirty so I wonder. Same with the carbs...said he pulled them apart and replaced all the brass, but there is so much dirt on them I'm pretty sure they didn't come fully apart.




Closer view of the frame where it was cut

That one will keep you busy. What flavor of 650? A ‘78 C2 was my high school transportation.

Yes, busy for sure...I need pretty much everything. It's a B version. Original had spoke wheels, same size as the Zed. I have a spare front from a 77 KZ1000 and a spare hub and rim from a Z1B, so I only need spokes and I've got a roller!!

I might have, might I say twice. A counter sprocket cover. I had a few 650 item tossed into a parts lot I bought several years ago. It could be from a 79 1000 though. I’ll dig it up

I think B and C model have the same rear subframe, but D won't accept B/C ducktail and rear fender.

Thanks so much for that comment seanbarney. I bought one on ebay two days ago...it came off a '79. Should do the job.

I've finished cleaning the frame and set it aside until the tail piece arrives. Then off to a welder to attach it and then down to a friends place in Chilliwack to sand blast the entire frame. He also has a dry vapour blaster and an aquablaster so I will try to disassemble the engine and take the parts down for cleaning.

Today I started taking the engine apart. The PO said he rebuilt the bottom end and changed the valve guides. At first I thought he was lying, but as I pulled the engine apart and saw the new gaskets I realized he had actually had the engine apart. For the most part it looks clean, but dry...no evidence of reassembly oil. The piston tops are still pretty black. Most of the exterior needs a thorough cleaning. The M6 bolts felt really tight when I removed them...not sure if they were torqued properly.

This photo shows the valve cover. It needs a good cleaning. PO had bought a set of NGK B7 plugs. B8 are the standards according to the book. Note how the valve gasket was designed for a smog head.


Photo of the back end, showing the dirt left on the engine during the PO's rebuild. He used Permatex on the cases and it looks to be a bit excessive on the outside. Hopefully not the same on the inside...this would have plugged the oil strainer if the engine had been run like that.


This photo shows the front...more dirt.

I think kz650 uses B7 plugs

The downloadable manual on this site for the '77 version says B8. I haven't found a '78 manual but am assuming it's the same.

hardrockminer wrote: The downloadable manual on this site for the '77 version says B8. I haven't found a '78 manual but am assuming it's the same.

Be very careful about the plugs. The original manual shows B8ES but that was an error. Every later Kawasaki Service Manual specifies NGK B7ES or ND W22ES-U spark plugs. I am very familiar with this issue because I am the original owner of a 1977 KZ650-C1. The first time I changed the spark plugs I used those specified in the original manual and those plugs fouled and had problems. I bought a later manual and found the correction, and after changing plugs to the new specification I never had another fouling problem. I have found that the ND (may be labeled Nippondenso or Denso) ND W22ES-U spark plugs work great in my 1977 KZ650. Ed

Thanks for that information Ed. B7 it is then. The plugs I have are brand new.

Here are the counter sprocket covers. If they fit one is yours.

If they are not 650, then I’d appreciate it if a member can identify them.

hardrockminer wrote: Yes, busy for sure...I need pretty much everything. It's a B version. Original had spoke wheels, same size as the Zed. I have a spare front from a 77 KZ1000 and a spare hub and rim from a Z1B, so I only need spokes and I've got a roller!!

the Z1 hub is different from the KZ650. also KZ650 has a 17mm rear axle. im sure it could be made to work.