Of Minds and Motorcycles

I Got 99 Problems

I got 99 problems...

Swingarm swap

And mounting a swingarm to a frame is one

While looking for a swingarm to swap into El Citron, I was so focused on making sure the pivot width was similar between the old and replacement swingarms, that I completely overlooked the fact that the chain won't fit! Not that I thought it would be an easy swap, but I guess to a certain extent I thought I would deal with problems as they came up; and well, a problem came up.

"Brian, what's a swingarm?" - Friend who isn't into motorcycles, but is very supportive of what I'm trying to do.

Simply put, the swingarm is that arm at the back of the bike that holds the rear wheel to the frame and swings up and down. It connects to the rear suspension and keeps the rear wheel attached while also allowing it to move up and down with the terrain separate from the frame.

Swingarm from a KTM 690 Duke; Photo from RideApart

I decided to go with the swingarm from a Bandit 600 since the width of the connection at the frame is only slightly wider than the current mounting points. This means that I could get away with shaving a bit of material off the swingarm in order to cram it into place. What I didn't realize is that since the S3 is built on such a chintzy frame - or at least a small one relative to its power output - the chain line would go right through the left frame tube. I realize now that the modern swingarm swaps I've seen on this bike are from 250cc bikes such as the Yamaha TZ250. Ideally I'd put modern wheels from a Ninja 250 or something similar to make it fit easily. A short wheelbase and skinny tires would match the frame well. The drawback then of going to a wider rear wheel is that the frame will have to be widened or completely redesigned. The benefit is that I'll have a wider rear tire; more fitting for such a powerful beast.

Bandit Wheel

Wheel from a Suzuki Bandit 600

S3 frame

The swingarm pivot on the S3, too narrow

Nothing is impossible though, and now it's just a matter of making a new plan based on the parts I have. I've looked into what other people have done and realized that widening the frame isn't as uncommon as I thought. Classified Moto, a company I look to for inspiration, had to mount an entirely new boxed section to the frame in order to fit a larger single-sided swingarm onto a XL600R. Another builder decided to weld in a new wider section for half of the frame; a decision which made him realize he could have just designed an entirely new frame from scratch.

So I now have a choice between 3 options:

1) I go the Classified Moto route and weld-in a new section wider than the existing tubing. This will require a jig and a new set of aligned swingarm mounts.

Classified KT600

Classified Moto's KT600, with new widened section for swingarm mounts. Photo from Bike EXIF.

2) I make wider tubing for half of the frame and cut and replace. This will require a more complicated jig along with new engine and swingarm mounts.

Widened frame on an S3 to fit an SV650 swingarm. RobbieRob of wforiders.com

3) I just go all the way and make a new frame from scratch. This will require a complete jig with everything aligned perfectly. All mounts will have to be recreated and aligned; otherwise I'll have a bike that likes to turn in one direction only.

I'm leaning towards Option 1 since it's probably the easiest, and it keeps the look of the existing frame for the most part. Whatever I choose I'll have to build and tack weld everything myself, and then get a professional welder to do the finishing welds. They're going to be critical welds which will need to be bulletproof.

Brake disc

Bent brake disc

Oh yeah, and the brake disc from the rear wheel I got off of ebay is all bent! Damned ebay. The rest of the wheel looks good luckily, and I didn't pay all that much for the entire thing, so it's not a big deal. Hipster lamp anyone? Made with real brake disc! Keep an eye out on Etsy for my new line of chachkas made out of old motorcycle parts! Chachka-Moto.

I'm kidding.

Or maybe not, depending on if I need money next month.

Stay tuned for more updates!

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