1975 KZ 900 , ZRX Swingarm, 89 GSXR front end

Hey thanks..

I sketched out (digital sketch), the fixture I built to center the rear wheel to the front.

After centering the wheel, I laid a long straightedge across the rear sprocket. Examining the clerance between the straightedge, and the flange of the countershaft, we came up with a 5/8" off set for the countershaft.

The rear sprocket, was ordered from sprocket specialties.

www.sprocketspecialists.com/

They are a smaller company, and have great customer service. I talked to the tech on the phone. Sprocket specialties made a ZRX sprocket with .050" removed from the wheel side of the sprocket. This is much easier than machining the carrier, and only cost ablout 20 bucks extra.

The spacing on the oppsite side from swingarm to the flange on the wheel to center the rear wheel was 1.330".

As I posted on another thread, the Japanese were using a very large tolerance, to center the neck on the steering head. It is very important that you align your bike, because they are all a little different.

Oh yea..

1 additional note well 2.

1. I am using a 180/55 Dulop sportmax tire it has a thinner profile for chain clearance.

2. Sprocket specialties encouraged me to use a 520 chain.

I should have listened. the 630 chain just clears the frame, but if it stsrts to smack around, it would have hit the frame, so i had to cut some clearance into the frame. Then put a plate over the cut section for strength. The 520 set-up would be much easier.

hey don't shoot the scooter it would make the perfect pit bike for me.

The "Scooter"..

Until 2008 facts about the scooter were mainly "Classified".

I can reveal a few Unclassified facts at this time. The scooter was developed under a Defense Contract on or about the year 2003.

The mission history is still protected; for the most part.

The scooter was a pit bike for Stoppee, and 341 racing in the WMRRA series in the Pacific Northwest. Unlike most pitbikes, it was not pimped out with long travel suspension, or an expensive paint job. Mission focused we like to say.

Developed at a super secure "Skunk Works" location, the top speed and horsepower figures are protected and cannot be published. The cardboard/fuzzycloth/fiberglass front fairing is inpervious to radar, IED blasts, birdstrikes, and some say even bulletproof, developed through months of wind tunnell and battlefield testing.

As it cruised around the pits weekend to weekend, a few smaller minded people made fun of it's appearance. However, oonce a year there is an annual pit bike race at WMRRA events. The scooter with 341 piloting won easily.

Perhaps 341 can release the details of that race. All I can say at this time is it was "banned" from ever participating in the annual scooter race again.

The scooter makes an interesting sound as it lands from jumping off berms at the track, something like a Couch being dropped from a two story window..you know..KKKLLLlluNNCchhhhhhcc!!

The pipe (exhaust) was designed using the most up to date 3d Cad software available tested and proven to scare weman and children with its "bark". In fact unbrella girls won't get near it even if it's turned off and parked.

The scooter actually crashed on turn 6 or 7 at Pacific Raceway, confusing the corner workers, as it ahh was not actually in a "Race".

People would gasp as we would simply jump off when it was time to stop for a burger, letting the scooter slide on its side to a full stop in the middle of the BBQ area. (See "Bulletproof section").

Currently in mothball storage somewhere in the Pacific Northwest, the "scooter" lies in wait for the next "Mission"


Stoppee or 341 feel free to add to or diispute these facts.

That is exactly how i figured out my rear end.my front end must be off center. i took great pains to line up the rear to the front,now the rear looks off center. but it handels great.(for a KZ).
I used a 5/8" offset and had to heat inside the frame with a torch and squeese it flat with a c clamp. also had to grind the inside footpeg mount off. its fine now.
From what ive read,the concensous is that a 520 chain isnt strong enough.

The 1000cc superbikes use 520 chains, so there is no doubt that they'll stand up to a 200 hp bike. However the racers that use those chains change them on a pretty frequent schedule. Having said all that I'd have to recommend the 530 instead for it's longer life, and the comfort of being able to ignore it. The weight loss of the smaller chain and sprockets is significant if your bike doesn't weigh the same as a KZ. Since we are talking KZ's and not modern aluminum framed race bikes the weight loss is unimportant and the longevity of the heavier change is more important. All IMHO.

That scooter has seen speeds that I wouldn't have believed if I weren't the idiot riding it. I can't remember a lot of the handling and jumping characteristics of it though, as there was tequila involved at that point. Troy341

Hey thanks for the specs and drawing. I was a little worried about finding a machine shop to work on the cush drive. (or understand what I was talking about)
I think I would rather run a 630 chain. This bike is heavy and makes torgue like, RIGHT NOW!
Thanks again.

i have been running the 520 non o-ring chain since i converted my z1r over to the r1 rear wheel tire and brake.i ride harder than most around me and always have.i haven't experienced any more excessive chain strectching than i did with my old skinny 120 tire and a 630.i just purchased a new o-ring 520 because i am fixing to build me another offset countershaft sprocket in an 18 tooth to get my gearing back to where i want it.i won't stop with the 520 because it works for me.that's my .02 fwiw.
here is the bike i speak of.

leon holmes

tk11b40 wrote:

Then just have a buddy help you ease the frame over the engine, it's even much easier to get the mounting bolts in, as there is almost no load on the frame.

i always lay the motor on a blanket and drop the frame down over it

tk11b40 wrote:

The 2005 photo, is after powdercoating it the first time. We tig welded a Kosman gusset kit in. I had decided against teh zrx swingarm in favor of a GSXR 600 swingarm. The 600 swingarm fits right into the frame no sweat.

Well My buddy has a zrx so we took his swingarm out and the rear wheel, put it under the frame, and man it looked good.

So I had to cut the stock bushing sout, and weld in new frame bushings. This was all done with a series of fixtures a good friend of mine helped to build. He is known only as the "Wizard". Very very good at what he does. We welded in the new bushings in perfect alignment.

Next we were concerned the super stiff swing arm would transfer flex into the rear of the frame. Fabricated more gusstting and welded it all in, soking Powdercoat 1 in the process.

i like the way you did the rear shock and fender mount bracing ive been scrating my head about how to beef up that area!B)i was thinking about putting a cross brace just ahead of where you did yours where the down tubes and top tubes meet just ahead of shock gusset areaB)

531blackbanshee wrote:

i have been running the 520 non o-ring chain since i converted my z1r over to the r1 rear wheel tire and brake.i ride harder than most around me and always have.i haven't experienced any more excessive chain strectching than i did with my old skinny 120 tire and a 630.i just purchased a new o-ring 520 because i am fixing to build me another offset countershaft sprocket in an 18 tooth to get my gearing back to where i want it.i won't stop with the 520 because it works for me.that's my .02 fwiw.
here is the bike i speak of.

leon holmes

Leon that Z1-R is flippin' gorgeous. A set of usd forks and an R1 front wheel would put it right over the top, IMHO. Is that a ZRX swinger? I can't tell, it looks a little stretched too. Again, well done. Troy341

tk11b40 wrote:

The frame:

I keep goimg back to the frame cause it makes me so proud. All the welds have been ground to fillets making a smooth looking "sculpture".

This is the view from the front: