kz900-A4 Swing Arm ZX-6RR Swap

Hey all,

Obviously I'm new here so please ignore any old man ignorance. LOL!

Well after 30 years of waiting, I found the love of my cycle life, a 1976 KZ900-A4... Some will say she's ugly, not to me, she's awesome but she does require some cosmetic surgery (internal & external).


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Yesterday I scored on a 2003 ZX-6RR complete rear end (swing arm, 180mm rim/tire, rotor & brake assembly) and have begun the surgery.

Questions: NOTE, I have read every forum discussion on this, some helpful, some not fully explained.

I realize the ZX swing arm is wider and I will have to cut, grind & weld the frame for the wider swing arm. The KZ pivot bolt is 5/8" versus the ZX being 3/4" with adjustable pivot.

Questions, here we go...

1) Use the original KZ pivot bolt and sleeve the inner swing arm pivot tube 5/8" ID @ 3/4" OD or do I enlarge the frames pivot bolt to 3/4"?

2) I have read where bushings where used but not sure how this was accomplished. Any further information would be helpful.

It was mentioned not to enlarge the frame to 3/4" but no reasons as to why.

3) With the swing arm up in place, I'm seeing a slight as expected offset between counter sprocket and rear sprocket. I have read where a 3/8" Kosman counter sprocket is required. Anyone have further information on this?

4) Will there be enough clearance to the casing (chain/oil pump covers) using a 3/8" offset counter?

5) 530 vs 630 chain required or KZ900 O-ring chain?

Thanks in advance,

Old Man Rock

BTW in case anyones interested....
Future plans include ZX-6 or Zx7 front end, APE Big Bore block, APE 1075cc piston kit with K410 cams, Mikunui RS flat side 34mm carbies, DYNA S DS2-1 electronic ignition, Aztec dual 4" headlights, Corbin seat and to top it of 4 into 1 Kerker header.

Post edited by: Old Man Rock, at: 2008/01/05 12:08

Post edited by: Old Man Rock, at: 2008/01/05 12:10

Well I will start and say excellent choice in motorcycle and proposed modifications. Now on to your questions:

1) Yes, keep the KZ pivot bolt and have a machinist turn new bushings. There should be bushings and needle bearing in the ZX pivot point. Take the original ZX bushing and the KZ pivot bolt to the machinist and tell them what they are for and make sure they do tight tolerance work.

2) These bushings are similiar to the originals on the ZX but made to fit your pivot bolt.

DO NOT ATTEMPT TO ENLARGE THE STOCK PIVOT POINT ON THE FRAME!! You will most likely ream the holes improperly and this will throw the swingarm to frame alignment off.

3) The alignment will be off, you are putting a much bigger tire on the bike. I believe that kosman has the sprocket but you need to mount the rim and measure the offset, all of these bike are a little different and may be different by a mm or two. Try a dutch site called klasmo, they are the true KZ mod specialists.

4) You may have to relieve the countershaft sprocket cover a little bit to get everybody happy under there , but maybe not.

5) Definitely swap to the 530 o-ring. Lighter and it is thinner to allow more clearance on the frame of the bike. This also may be an issue.

This should do you for a while, get everything mounted and take some pics. Check out that web site Klasmo too, there is some really neat stuff there. Good luck and keep the rubber side down!!

Bdog

That is a nice ride. Would like to see pics of the progression as well.

Good luck.

start buy installing the arm with the kz bolt.u will have to file some material off each end of the zx arm first. just measure the width and keep track of how much material u remove from each end .now install arm and wheel ang aligne the rear wheel up with the front.this will center the rear wheel on the bike.i found that the wheel on my zrx was not in the center of the zrx swingarm .some guys move the wheel off
center to gain clearance, and report no ill affects.make sure u are clear on this as u ask questions. mine is centered so i cant comment on the affects of being offset.now that u are centered u can measure clearances and deside if u need to go off center.i had to heat ans squeeze the frame rails and remove material from my hub to gain clearance, and stay on center .i used a 5/8" 630 offset sprocket($60,from Pringles)
my project.
kzrider.com/component/option,com_joomlab.../id,103381/catid,11/

Post edited by: mark1122, at: 2008/01/05 15:16

Rock,
You got good advice; great project, good luck, I'm going to enjoy watching it come together. Oh yeah, POST PICS of your project and everybody here will be your best friend!
-KR

Thanks for the advice guys... Sleeving it is!
For the counter sprocket, get the conversion finished than measure for exact displacement. 530 chain as well.

Mark1122: What material did you use for your 3 piece sleeve? Almost looks like brass which I would have thought would be soft. Same time, I guess all that is required is taking up the additional 1/8" space inside the swing arm pivot tube. Thanks, I get it now!

By the way all, scored again, 100% undamaged zx-6R(636) complete front end (triple trees, forks, tire/rim/disk and calipers). I obviously am going to have a whole slew of questions regarding the lower tree steering stem swap but another time. lol! :blink:

I will keep all posted as I go. I am taking pictures throughout the whole conversion and will provide as I go.

Actually, I am planning to do a complete write up with images (tutorial format) from start to finish for other newbies such as I with all the collective advice from others.

Thanks again,

Old Man Rock

the matirial was brass or bronze? my machinist had it in stock. the kawi bushinigs look like the same stuff.
i am doing a zx9 front now. looks like my guy is going to press out the zx stem, cut a piece off the bottom and drill it out to fit over the bottom of the kz stem. then it can be pressed back into the zx tree.

bronze bushings are the aftermarket answer to the stock swingarm s tendency to wollow out the stock (softer) bushing material. Bronze is easy to cut, but tough enough to rest suspension on I guess.

Please measure the OD and the length of the sleeve from the zx6rr swingarm, and the length of the sleeve from your KZ900. I have done several swingarm swaps and been able mix and match sleeves from lots of donors to make things work. If your lucky you will be able to find a combo that works. My notes confirm that the sleeve from my YZF600 is .945in (24mm) OD, it is .629in (16mm) ID and it is 9.290in (236mm) long.

Good Luck,
Jon

OMR: I've done two ZX9R (inverted) front end conversions. First time, an pure mechanical genius named 'Muskgrave' worked the voo-doo on the front by pressing out the ZX9R stem, putting the old KZ stem inside and welding it together. The ZX9 stem is larger in diameter and therefore leaves a larger hole in the bottom (and top) triple for the KZ stem to fill. Chuck Graves laid the weld bead on the first set (for a racer that guy has some great machining and welding skills). Second time Brian Lewis at Extreme Cycles in Topeka, Kansas did it all. Pressed out the KZ and ZX9R stems, made a sleeve for the bottom triple, placed the KZ stem in and welded it in. The top triple was basically the same thing, he reemed the top triple hole a bit more so that the sleeve he installed there could have a shoulder on top and that shoulder acts as a collar or a spacer for the top nut. I think I put it in a post around here somewhere.

To me, doing a complete front end swap worked out waaaaaay better than piecing together all the parts that I thought would work...something that I did once before...lesson learned.

Again, nice project. Post pics!

-KR

Post edited by: Bad Kaw, at: 2008/01/15 18:34