Rear Swingarm Conversion Question

Well, I have been lurking around for awhile, joined recently and am going to begin a 1976 KZ900 project bike very soon. I have been accumulating parts and have a few rear suspension questions. I have been looking through the projects section at the rear swingarm conversions. What I would like is an aluminum rear twin shock swing arm for the rear. I have seen a bunch of monoshock conversions, but only a few dual shock ones done other than the ZRX conversion.

My question is, (I don't want to do buy a new JMC swingarm or use the ZRX one) so, what swingarm would you guys tell me to buy? I do want an aluminum one, but which is the easiest to fab up? Just so you know, I am pretty good at fabrication. So a little work is OK, but I don't want to have to re-engineer everything. I am going with a ZX6R front end if that helps. I like the look of the Sanctuary bike with the Sculpture swingarm, but that is simply out of my price range LOL.

My last question for now, I see many people doing the 530 chain conversion. why not go to 520? Does no one make offset sprockets in 520?

Any help would be appreciated.

I would suggest buy rear section as a whole from whatever bike you decide you like.then you arent trying to figure out everything like rotor size to caliper mt or,spacers wheel? most likely you will still need to fab some spacer off sets but having the whole thing kinda gets you started.less chasing around for this or that.good luck.

Suzuki GS1100 aluminum twin shock swingarm is another choice.

As mentioned above,the Zuki GS1100e swingarm is a direct swap.Also as mentioned get thr swingarm, the axle,the shocks and the chain guard as the Kawi stuff wont fit.As the Zuki stuff is as old as your bike,plan on installing new bearings in the arm.Spacers can be fabbed up using appropriate sized washers.Be sure and align the front and rear spockets so chain wear will be minimalized.did the same swap on my bike in a couple of hours so it really is easy.bj

Great answers, thanks guys. Now the next question, can I put a 180 tire in the GS1100 swingarm? If not, then I need another idea for swingarm. If I get a Zr750 Zephyr swingarm what size rear tire can I get in one of those?

Your project will entail more than just a swingarm swap, since you will have to convert from drum to disc brake. You will also have to make provisions for a rear master cylinder and such. A KZ100 would be a much better candidate for this upgrade. A GS1100 swing arm will not handle a 180 tire without major mods. You will also have to use an offset front sprocket and get a rear rim to match. This is a gs1100 swing arm with a 3x16 rim and a MT90 130 tire. The shocks are made for a leadwing so they are 1" longer

The Zuki arm is about 1.5 inches wider,2 inches longer and with the stock Zuki shocks will lower the bike 2 inches.I am running the stock Kawi rear tire and it is close from side to side but plenty room top to bottom.Have no idea about the other arm,someone else will need to answer.bj

Allright, more good info. Just so you guys know, I'm not afraid of a little work, I just want to try and minimize if at all possible. However, I am thinking that might not happen for what I want.

Here is a bike I built from the ground up. I did everything except the welding. It is a RZ in a 1990 TZ chassis. I do have fabrication skills...LOL

Back to the swingarm, I have a Kawasaki ZX6R rear wheel setup (except the swingarm) and the Kawasaki ZX6R front end. I want to make the back accept a 180 rear tire, but still be a twin shock bike.

Your best bet will be a Zephyr 750 or 1100 swingarm.

You can fit a 180 tire and a 5.5" rim into a Gs1100 arm. Check out www.suzuki-katana.com/katana_suspension.html and scroll down to the 5.5" Rim/180 Tire section for details.

Don't forget that you can also get an older Gsxr arm and weld shock mounts on and get your wider rim that way. I've done this and now I'm running a 160mm tire on a 4.5" rim.

Later, Doug

For dual shocks on the swing-arm, have some aluminum shock mounts fabbed and welded on... I have a 180 tire on mine with plenty of room for chain and tire clearances...

You'll require a 12mm (1/2") offset cc sprocket.

The ZX rear sprocket is a 530 pitch. Options are the 1979 KZ750 sprocket template is the same as the ZX6 if desiring to go to 630 pitch. Same time, American-Classix offers offset 12mm cc sprockets in 530 pitch as well...

americanclassix.com/streetfighter_conversions.html

KZ900 Stock gear ratio 2.333 @ 630 pitch
35/15 = 2.333
Stock front is 15 tooth
Rear is 35 tooth

@ 530 pitch
Front (15 tooth / 5) * 6 = 18 tooth
Rear (35 tooth / 5) * 6 = 42 tooth
42/18 = 2.3333

ZX6 suspensions... You'll love how smooth she'll ride...

OMR

Click > Shock Mounts at Z1E

Good Fortune!