KZ900 Streetfighter

How did you work out the rear wheel and swing arm issue?

Just looking back on the thread- couldn't see if you had the monoshock mounts done up yet. If so, could you post a few pics? I'm debating on what to do for mine. I have a few ideas, I'd just like to see a few pics if you've got yours in.

Devin

No problem, things are still in the fab stage, but I think you can tell how it goes together. I did the mounts a bit different than what I saw on other builds. I have one good pic of the mount installed, looking down under the seat, even if it looks terrible:

The mount itself is a piece of half inch 6061 mated to a piece of 2" 1/4 wall box tubing:

Mounted in the bike, the shocks travel is straight upward to clear all sides of the swingarm opening. The shock is pretty tight probably because its from a GSXR600 and the swinger is a ZX636. I read OMR's writeup last year or so to get an idea, I liked the way it looked and followed that almost to the T (it seems that conduit tubing really is just about the right size :silly: ). I pondered the upper mounting for a while before I decided to make it bolt in. For some reason I was worried about it being in the way, perhaps for battery clearance, but I went a different route there as well. I thought about ditching it and welding in a steel mount just to be safe. But it seemed that since most of the load (most of the time) would be upward, distributed across the 1/2" plate to the frame, and therefore the weak spot would be the tabs on the frame. So the mount has four weld passes on it and the frame tabs are made of extruded steel angle and welded on with three passes and then capped with 1/8" sheet to gusset to the lateral support tubes. The lower mount took less engineering. The ears are made from 3/16" steel that came from a.... Wait for it... Case VAC of about mid 50's vintage :lol: I welded the tabs to some DOM and used a pipe clamp to hold it to the frame so I could sit on it and set the ride height. Too bad I don't have pics of that setup, but it made getting it close much easier (but it still sat too high for my liking and I ended up using some Protek lowering links to drop it again :pinch: ). The goal was to have the bottom of the shock knuckle sit parallel to the ground.
I'd like to get some better pics but I think it will be a week or two before I get a chance, work has been killer the past couple weeks. I hope to get some parts cleaned and painted this weekend and hopefully installed.

Mounting the R1 wheel was relatively easy, but it took some thinking to know where tolerances could be taken or not or what parts worked with others. I spun out a couple spacers to get the rim centered as much as possible while using a stock 636 rear brake caliper bracket. With the wider rim though, there is the problem of countershaft-sprocket offset and finding an axle to fit. As of yet, I don't know of any axles that are long enough and with the correct diameter to fit both the hub and the swinger. First, I cut the R1 axle in half and sleeved it, with the plan of making a solid one from scratch to use with the R1 sliders shaved down to fit in the 636 swinger. Then, To combat the offset problem I set the rear sprocket carrier in the lathe and machine off IIRC it was 5mm. I don't have that wrote down though, but the easiest way for me to figure it out was with a straight edge against the sprocket and removing the sprocket carrier multiple times. After taking off enough material to feel comfortable with and meet the specs of aftermarket sprockets I ended up getting a 18 tooth PBI 5/8" offset sprocket. I was aiming for 13mm but I would have had to take off quite a bit of material from the sprocket carrier. The sprocket cover also had to be trimmed for the chain to clear as well. Another funny thing about the alignment is that I flipped the R1 sprocket over to shift the center of the chain toward the bike-center about 1/8". It made all the difference. I now have to use a 180mm wide tire and it leaves me with 3/8" chain clearance between the tire and the frame. I have to check again to see if I need to support the chain though. The 110 link chain was too short and 112 was too long, so to solve that problem I opted for a smaller 45T sprocket from Venom. The final drive ratio is 2.5:1.
I have pic or two of the bike for reference purposes that may help with the descrip here, but feel free to ask if anything is unclear. I wish I could give some more photos of all this right now, as it ended up being pretty involved and took about three months time to get it all worked out.

That's awesome info, thanks!

Sorry about being away for so long. After having to move back to my parents I have been getting the old garage straightened up a lot and resumed the project once again, while seeking a new job and pursuing school; alas, things have slowed down a bit. So far I have finished tearing down the engine and cleaning up and painting the cases and covers. I never really looked the engine over very well, but it turns out to be a replacement unit when i compared the numbers. So I have no idea what the back story is on that but here it during the tear down:





Most of the cylinders looked okay, one of them had a bad scratch, but the rest seemed superficial; I couldn't snag a nail on any. I decided to swap out the bad sleeve for one out of a set of fleabay jugs. The pistons had a lot of scratches and some dark patches where they galled on the cylinder walls. After going through the trouble of cleaning them up, I just pulled the trigger on a new set with rings etc. from Z1E. Now I can sleep at night :lol:

DoubleZed wrote: . . . never really looked the engine over very well, but it turns out to be a replacement unit when i compared the numbers. So I have no idea what the back story is on that . . . .

For reference --
Per Zedder:
Year & Model '76 KZ900-A4
Frame No. Range Japan MFR Z1F-085701 - 117060
USA MFR Z1F-500001 - 510340
Engine No. Range Z1E086001 - 138846

Good Fortune!

With a new heavy duty timing chain installed I checked over the bottom end clearances and assembled it. Other than the pistons and cylinders the engine seems to be in good shape. When the oil pan came off there was not a lot of gunk built up or any metal bits laying in it. The tranny looked great, so no need to dig into that.
I painted the cases with Duplicolor engine enamel semigloss black, although it looks more or less flat. the rest of the covers are the same semigloss paint but they actually look like semigloss.

The jugs are gloss black and so are the points and dynamo covers. All the covers were glass-bead blasted and then washed again and again, the jugs and cases were blasted with aluminum oxide.



There is a huge difference that's for sure, I wish I could have just cleared over the glass beaded stuff but I was afraid it would yellow.
After thoroughly cleaning everything, it was all baked at 200* for an hour and allowed to cool to about 100* when I shot the paint.

I tried to keep as few light coats as possible to avoid a heavy build and make things more prone to chipping. Honestly though, It doesn't matter it will still chip if it gets knocked hard enough.


Now I decided to use Duplicolor paints because I thought about what would happen in the future; if it did get chipped, I could easily repair it, versus if I used a specialty coating like I thought about, and not be able to blend the repair. I would have to strip the entire part and re-coat. When I searched around to see what others used, Duplicolor seemed to be a common one with few bad reports. Just for grins I looked it up again a few months later to see if anything had changed and now see ads for VHT brand "engine case paint".... It must be new, since I didn't see it before or in any of the retailers like O'Reilly's or Autozone, and they kept up with stuff like that where I was working. lol

For the top end, other than fresh pistons ( and I still need to weigh them! ) I am kinda OCD about head gasket leaks, so one of the first things I consider on every engine I have built to date, is heavy duty head studs. Some might say its overkill on a stock motor, but if I ever decide to go bigger I will already have them and for the time being I know that I can torque it down without flinching, so APE studs and nuts for the win!! For anyone who has thought about doing this to their engine, a word of caution: The original studs in my engine were tight as a ticks @$$ and took a LOT of heat and torque to remove!!! :woohoo: I spent about 2 solid hours twisting them out. Doubling up some nuts? Forgettaboutit! The only thing that I could clamp onto the studs tight enough was a bench-top vice with a length of pipe... and turning a little ata time between applications of heat, penetrating oil, and then mechanics best friend (wax) over and over. I had my work cut out for me :laugh:
But with the new APE's in, I followed a little bit of advice I read a while back and put heat shrink over the 8 exposed studs. Apparently that will make removing the jugs in the future "easier", but I thought it would do better just to prevent them from crusting in the distant future. So I wiped them down with heavy oil before slipping the shrink on.


I also rewired the dynamo, per a few suggestions I read on here. Unfortunately, I missed the part where I should have bought a new grommet from Z1E when I placed the order with the pistons :blush: So I put it together with a copious amount of RTV.....

Since I am only one man, I found it easier to move the engine without the top end. I slipped the frame over it without a hitch (or scratch) and the heart was once again mated with the body


And the rear end installed with a couple temporary bolts. The swinger was repainted with a rattle can paint I brought back from my old job. It looked to be some custom mix from a local shop called "brilliant black" by SEM, black with metallic flake. It matched the original swingarm paint almost perfectly, had I not put clear over it. I will have to see if I can find a place that will mix and fill rattle cans and get some more.... I also repainted the yellow shock spring and upper mount gloss black.


For the upper mount, I made a couple steel inserts on the mini lathe (all I got ) to press in with a bit of red lock-tite.

Thanks Patton, I will have a looksee at those numbers once again and post them here and learn a bit more about this bike. Happy Thanksgiving!

Looking awesome! I'm just waiting for my stuff back from Leon so I can start my rebuild process too. :whistle:

great job.......cant wait to see it finish. well be looking for more info as you go as im also just starting my project.