Z650 / 1170 Project

I need another project like a hole in the head, but I was offered the basics (very basic) start of a project as part of a swap, and since it was an old Kawasaki inline 4, with a deep breath I took it on board. T
What I have is a 1978 Kawasaki Z650 frame, a Z1000 tank and most of a GPz1100 motor in pieces.

If you've checked out the pic below already, you'll have noticed the frame isn't quite as it left the factory. The frame is to be widened by about an inch and a half (35mm) to accommodate the GPz1100B1 motor, along with modern wheels and swingarm. Well, I say Gpz1100, but I suspect when we've finished with it it'll be a bigger than 1100cc, as the block is badly scored and needs a rebore.

It'll be having better suspension, but not USD forks. As for the wheels, I have a pair of homemade 17inch wheels which came off my old drag bike, not sure if they'll make the final build, but they'll do for now.

I started the project work more than a year ago, and progress is slow due to C19,  but I hope to have it on the road by this summer of 2021.. famous last words..  Though I do have a couple of other projects that take up most of my time and money at the moment.







 

For the swingarm, the first idea was to use an old ZXR monoshock arm, modified to twin shock, with a pair of billet adjusters .. that happened to be going spare. But it needed a lot of work and the result was going to be too heavy. Luckily I was given the arm from a ZRX1200, which was covered in melted plastic, had small hole in one of its braces and had been narrowed at the pivot... Not ideal, but it was free, so I took it home.

Had the damage welded up and then I cleaned it up in a mates blasting cabinet. My old drag bike donated an as new rear Brembo and a mount was machined up to fit it to the ZRX arm and billet rear wheel.. So far so good, and not a penny spent.

Later I had the arm powder coated, and a billet mount made for the caliper.






 

I'm skimming through the last years worth of work, so things didn't as quickly or smoothly as it seems.. Early last year, I could finally mock up the rolling chassis having been given a pair of 41mm forks of the right length (they need rechroming so weren't worth much). I found the billet yokes on my mates workshop shelf where they'd sat unused since he made them a decade ago. Waste not, want not...

By todays standards the forks a little spindly at 41mm, while the yokes are equally modest. They may be replaced with something better, but for now they'll have to do.



The top yoke was drilled to take the risers, all the spacers and engine bolts/brackets have been made.. the bolts being made from 316 stainless. I spent far too much on a pair of remote reservoir shocks by K-Tech. They are built to the spec of a ZRX1200 (365mm) but with slightly softer springs, as the bike should be lighter than a standard ZRX, while its unlikely it'll ever carry a pillion.

The white cardboard over the drive sprocket is just to give me an idea of the size of alloy plate needed to make the outrigger bearing support.




The Z1 side panels and tail unit arrived, they are very well made, come from Japan I think. Sadly and not unexpectedly the tail piece wont fit on the now widened frame. I was hoping the tail unit would have some flex so it'd go over the seat rails, but no chance. 

If the tail piece had been made from fibreglass I'd have been tempted to cut it in half and widen it to fit, but its made from ABS and its too nice to cut up in any case. Instead I bought a cheaper fibreglass Z1 tail piece, and promptly cut it in half. It fits ok when the two halves are angled in the pic below, but not sure yet what the best looking option of positioning them before I fibreglass them back together.

There are a few unexpected problems with trying to fit early Z1 bodywork on a 650 frame, one of which is that the fuel tap will have to be moved forward as it hits the longer Z1 side panels. I thought the tank was from a Z1000, but it seems its from a Z900, which have a different petcock position.

Meanwhile the inner plate for the outrigger bearing support is almost done, its from this plate that the outer plate (which carries the support bearing will be mounted from, via stand off spacers. This outer plate will also be used to mount a clutch slave cylinder to convert from cable to hydraulic clutch. 

The outrigger plates and support bearing were finished, using an ZXR750 Oberon slave cylinder, as its one of the most compact slaves from Kawasaki, smaller than a ZRX1200 which was too big to fit .. don't ask how I know! There is also a roller bearing to support the gearchange shaft, which isn't fitted in the pic below



I then took the cases and the crank, gearbox etc to my mate, who will be building the engine for me.. I have neither the time, space or skill to build the motor the way I want.

This is when things started to go wrong..

With the cases cleaned, a problem was found with the top crankcase.. it had a crack....

This was annoying to say the least, as I'd just spent £360 on the ceramic coating of the cases.. But I know a good welder, so I took my case and my sad tale to him, and he said he could repair the case... or at least make a start on the repair, by grinding away the area of the crack and rebuilding it with weld. I would then have to get the case machined and drilled back to standard.  Thankfully the case was repaired and the engine build could continue..





It didn't take long before we hit another problem.. some of the case hardening on the crankshaft had worn away, so that crank couldn't be used. But a second crank was found, that my mate Jeff had rebuild awhile ago, and that went into the engine. Then had to wait for parts to arrive (APE head bolts etc) before the block can go back on.

In the meantime, I set about the tedious job of polishing the engine covers.. Only to find the points cover was cracked, and the clutch cover had a weird shallow dent in it. (Above the K in Kawasaki). No idea how it got there as there's no other damage on the cover. Someone thought the original bike had crash bars fitted and in a crash the bars bent and hit the cover.

I decided against using these covers, and instead of hitting Ebay for used covers, or buying some cool aftermarket version, I'd have my mate Jeff make them for me. I liked the one I'd seen on one of his projects, so mine will be similar, but not quite the same. Just ordered all the alloy plate to make them. The alternator cover would be to tricky to replicate, so for now the engine will be getting a standard cover. So I guess I cant avoid polishing that one.

With most of the parts arrived, the bottom end could go together, and with the heavy duty APE cylinder studs in place, the block could go on next. In the pic that was about to happen. With that done, attention turned to the head.. and more headaches..

The 1000J head is from a bike imported from the US, and its had a hard life. Some idiot in the past had used a too long bolt in one of the cam caps, which cracked the head immediately below the bolt. Once again, the damage had to be ground away and weld used to build up the area, before being shaped back to original (still not finished), see the pic with the arrow below. In addition a couple of the cam cap threads were damaged... a common problem it seems, so all sixteen threads will be heli-coiled.

But the problems don't end there... all the valves, valve guides are worn, and so will need replacing. While the valve seats will need to be recut too. Its all turning into an expensive rebuild. Shouldn't really be surprised as I started with a set of cases, barrel and head, and not much else, have to remind myself that these engines are now 40 years old.


 

Making a new clutch cover..

I had been intending to use a set of lightly used 1135cc pistons, which came as part of the initial deal, but sadly one of the rings was damaged. It turned out replacements are rare and expensive. The only ring kit I could find was in Germany and costs almost as much as a full piston kit. Therefore I decided to have the block bored out (again) to 75mm to get 1170cc and fit a new piston kit... more expense.





The head was away for months being rebuilt by a drag racing tuner, but it came back better than new, and once ceramically coated could finally go back on the engine. The engine also gained a homemade billet manual cam chain tensioner, along with a new set of Mikuni RS34 flatslides... by this point the budget had gone out of the window..

I also needed a stator and rotor, starter, starter clutch, idler gear and so on...  next time I'll buy a complete motor..  




 

A friend was breaking an R6, so I bought the front end at a good price, so the 40mm Suzuki forks are going, to be replaced with the 43mm forks from the R6, fitted into one billet yokes. I'll also use the R6 discs and blue spot calipers.


Next widened and mounted the duck tail, still needs cleaning up before paint, but turned out ok.



Also test fitted the new billet yokes to take the wider 43mm forks in the pic below, after which I decided to machine the underside top yoke so it sits over the adjuster nuts, as it'll look better and give an extra 10mm or so of ground clearance, at the expense of making adjustment trickier.



Finally made a seat base in fibreglass, still needs a bit more work before it cam be upholstered.


And that brings things up to date, we are still in lockdown here in the UK, so getting anything done is very frustrating. The frame will be going off to be powder coated soon, but first it needs a stainless rear splash guard and undertray.

 

Hi Bevelhead, is that a Laverda SF engine sitting in front of the frame and engine in the first picture? Looks very interesting!

Not a Laverda, but a 60's Honda twin, with a one off block and supercharged..

Wow, that's very interesting. Maybe you could post about it in daily chatter when you get it up and running. I would love to see it when it's finished.
Cheers.

The blown Honda is my friend Jeff's, its from a drag bike he built in the mid eighties, he sold it a few years later, and by luck he found it again for sale recently, so had to buy it back. There's not much left of the original bike, as he's changed almost everything. Don't know when it'll be finished, as lack of money slows progress.

Here's a pic of how it looked when he bought it back, and how it looks now.



When/if it ever gets finished, I'll film it running and put it on YT. All our various builds (including the Z650/1170) are on YT. The most recent vid is here..