TOPIC:

Hey gang. I'd appreciate a little input on a swingarm modification I am looking at doing for my 650/810 project.

I have a customer who owns a fabrication/machine shop and he works with all types of metals.

What would you guys suggest for strengthening, an underside swingarm brace or should I just go balls to the walls and get him to fab a boxed aluminum swingarm (similar to a modern crotch rocket) or chrome-moly replica of my stock '77 swingarm. I am looking to retain the original stock rim and axle.

Cheers-Colin Firth-Ontario Canada

ive always been a fan of cal fab swingarms,they are big and beefy aluminum swingarms i can see about posting a picture if you need some ideas.

A boxed aluminium would be easiest. I always liked the look of a braced swingarm. A chromoly would be ultra wow and keep it stock sleeper looking.

An easy way to get a bit more strength, and retain the stock (sleeper) look, is to go with a KZ1000 arm, they are made with a bit thicker tubing, and are just a bit longer(I think 1 1/2 inch).
If you do get a custom chromoly one to "look stock", I would base it on the 1000 arm instead of the 650 arm, just to get the added "beefyness" and a slight stretch.
Scott

those chrom moly box section swingarms twist really easy also if you put a lot of power or a sticky tire on em also unless you use the outboard"clubman" support on them .i guess im just a sucker for nice looking heli-arc welds on a piece of aluminum looks like a roll of nice shiny nickels! goodluck,happy wrenching!

Thanks gang. Wireman, you definitely know of what you speak! Gotta love a good row of nickels on any metal. My Dad spent over 40 years with his face under a welding mask. I learned a little from him when it comes to laying down a good solid bead that also looks purrrrdy.

I had a chat with the machinist and the boxed aluminum or chrome moly design would have been nice but the price would have probably come in around what a new crotch rocket swingarm would have set me back.

I am probably going to have an underside swingarm brace made of mild steel tubing slightly smaller than the factory swingarm diameter with several pencil-sized triangulated braces kinda like the ladder bars I had for my '70 Chevelle SS.

Until we fab it up I can't guess its weight but it should come in under 5 pounds. I have a friend who put a similar one on his Z1r and he said he didn't even know it was there.

Cheers-Colin Firth -Ontario Canada

'77 Kz 650 Custom - (Miss July on 2006 Kzr Calendar,) Being rebuilt again with...Wiseco 810 kit, Kz750 cams, Kz750 intake valves, 750 GPz springs, Ported head, WG Mikuni 28's, Filters, Dyna Ignition and coils, MAC pipe, 13 tooth sprocket, going back to original '77 Moon Dust Silver. Goal is to have a stock-looking bike that will tighten up any loose dental fillings off the light.

there was a couple nice looking braced swingarms on that old superbike post of cruising rams last week,might be able to get some ideas from there! goodluck,happy wrenching!

Heres a pic and link to a Minton modification on a Yamaha XS 650 swing arm.
Fish

www.650central.com/tech/mintonmods.htm