Z1OwnersClub GB

I really didn't need another project, since I already had three in various states of completion, but then again, when the other three are finished, don't want to get bored... So I took it on board, but as my 2020 project. The good news was it didn't cost me any cash, as I swapped an old pillar drill for it.

The 'it' being a 1978 Z650 frame with logbook, a Z1000 tank and most of an early GPz1100 engine, in pieces.
However, the engine wasn't the only thing in pieces, as the frame had been chopped up too. My mate had done this in preparation for widening the frame to take the bigger engine, and to allow a wider swingarm / rear wheel to be fitted.

My first thought on seeing the frame was that it was a bit extreme, did it need to be quartered like that? Oh yes I was assured by my mate, its not a problem, wont take long to weld it all back together...

I helps that my mate is well versed in old Zeds, and has a frame jig..

So what we started with was this..

Once the frame was on the frame jig, an old set of cases were used to work where the new mounts should go etc. It was decided it would be easier to cut out the lower frame rails and replace them rather than try to modify the originals. Also since we were going to fit a wider back end, the swingarm mounts were drilled out and new mounts welded in to take a 20mm spindle. The area was reinforced too. The down tubes were braced and another cross brace is to be added to go behind the carbs, and it'll no doubt get a few more mods along the way.

The Z650 frame didn't have a swing arm, and even if it did, once the frame has been widened it wouldn't fit anyway. A different swingarm was needed. From our pile of junk.. er .. valuable old spares.. we found an old steel arm taken from a 90's Kawasaki ZXR750. But ZXR750's were mono shocked, while the Z650 is and will remain twin shocked. Oh and it was also at least 100mm too long. Not a promising start.

However, in the workshop I found a pair of 'spare' one off alloy wheel adjuster blocks.. which I soon snagged for the Zed project. Next I chopped the swing arm down to size by cutting off its original wheel adjusters, in preparation for fitting the new adjuster blocks. The mounting bracket for the mono shock will have to be cut off and new shock mounts made and welded on to take twin shocks too.

In the photo you can see that the new alloy adjuster blocks are far too wide for the swingarm, but that's ok, as the extra will be needed when we add an under brace to the arm.

While the new swingarm would look pretty cool, I wasn't too happy with the idea. First it'd be a lot work to complete it.. need to make a jig to hold it all in place for welding, then when it was complete it would be pretty heavy, too heavy perhaps.

I mentioned the problem to a mate, who is building a big bore Z1000Mk2, and by luck he had a tatty looking ZRX swingarm, which he said I could have for free, as he now had a better one, and he'd only used it for setting up. So it came home with me. It did have a couple of issues.. first it had been machined down to fit the old Z1000 frame (where the bearings fit), second it had a small hole in one of its braces, and finally it was covered in melted plastic. Then again it was free

I used another mates blasting cabinet to clean it up, then had a local (and very good) welder repair the damage to the under brace. Next the eccentric adjusters had some deep scratches, so they went on the lathe to be cleaned up. That means they'll need to be re anodised at some point. The arm didn't come with any spindles or bearings, but turned out ok with a little work..

In an ideal world I'd like to run it on 18 inch spoked wheels.. alloy rims, stainless spokes lovely. But even suitable hubs are expensive, never mind rims and spokes. I can lace them myself, but even so, I had to look elsewhere.

The obvious answer would be to buy a pair of 17 inch alloys from a modern-ish sports bike, and that's an option for the future, but in the meantime I didn't have to look far to find a pair of wheels to use for now. I had a pair of billet wheels (made by my mate years ago), which had come off my old drag bike. The rear came with a new sprocket and a disc, and with new spacers, a one off brake mount and the Brembo off the drag bike, the back end was coming together..

Bevelhead wrote:However, the engine wasn't the only thing in pieces, as the frame had been chopped up too. My mate had done this in preparation for widening the frame to take the bigger engine, and to allow a wider swingarm / rear wheel to be fitted.

My first thought on seeing the frame was that it was a bit extreme, did it need to be quartered like that? Oh yes I was assured by my mate, its not a problem, wont take long to weld it all back together...

Interesting project..
A bit overboard and unnecessary chopping the frame like that to fit the bigger motor though .
It's a common mod and just a change of engine mounts.
Maybe there's another reason why it was done like that ???
Looking forward to more instalments.
Good luck with the build.

I asked the same question later, the answer being it would be easier to fit a wider swingarm / rear wheel if the frame was widened by one and half inches. You could do that without widening the frame of course, but my mate didn't like the idea of having to space out the top shock mounts to line up with the wider swingarm shock mounts.

Hi Bevelhead
seems to me like you know what you're doing. Not my piece of cake but it looks very promising. Good luck with it!
GrtZ
Philippe

Very interesting. You sure have a great bunch of clever friends will watch this wit interest

Nice wheels... interested to see this progressing.

Ditto on the wheels.

Looks luverly.. I have a csr650 and a z1000j lump,erm???? Tempting conversion. Watch this with interest and see what happens

Did you ever think about a gsxf motor? Seems the mods are a bit heavy handed when that would of fitted easier? I have probably missed the point,again!!

drew

An interesting build.. Good luck.

No I never considered using anything other than another air cooled Kawasaki engine, it'd be a lot easier using a Z750 motor, but the 1100 was part of the deal, so that's what its having. Talking of Z750's, my first 'big' bike was a Z750L3 bought new in 1983. Loved that bike, did nearly 200,000 miles on it without a problem, except for a rusty tank (it went behind the badges where water collected). Pics below were taken at the Bol D'or 24 h race at the Paul Ricard circuit.. for us campers it was called Paul Rock 'ard for good reason.. I took my kid brother along. We went back a few years ago.. only took us 31 years lol..

chrisNI wrote:Nice wheels... interested to see this progressing.

The front was originally made to have just one disc, but being built up, the hubs can be unbolted and machined to take a second disc. This is how they looked on my old drag bike..

Bevelhead wrote:

chrisNI wrote:Nice wheels... interested to see this progressing.

The front was originally made to have just one disc, but being built up, the hubs can be unbolted and machined to take a second disc. This is how they looked on my old drag bike..

Hardtail - oooh the pain.

PS - following this thread with interest.