Snake - a never ending story - Part 3 : Snake III swingarm

Sorry for all the BIG images on this page. They are necessary to explain some of the problems I encountered.

A friend of mine had, next to an XS 650, a Suzuki GSX1100 with spareparts, and saw that the swingarm would fit, with some serious adaptation and made a very nice bike based on that conversion. He was so nice to do this to my frame too. (thanks Michael)

My frame with the Suzuki GSX1100 swingarm and the mono shock installed. This was a point of no return as the adaptation of the frame was quite extensive.

All pictures except first one and bottom one are shot with the frame upside down.

Something kept bugging me - something I did not know would cause me such problems later on.

Difficult to explain, but take a look at the picture below. The chain has no play when the swing arm is up. But it has way too much play when it is down.

The red line goes through the center of the engine sprocket and the pivot point of the swing arm. The green line goes through the centre of the rear wheel sprocket and the pivot point.

You can see the chain is being pulled apart by the sprockets.

Only way to solve this (simple way anyway) is make that the green line is a lot closer to the red one. I checked on a standard bike and the green line is just underneath the red one and crosses it when the swing arm is forced up.

Pity - as I liked the aggressive look of the back being so high.

I changed the top mount for the shock absorber. This is a lot better, I think. Still - I have encountered a couple of things I´m unhappy with.

I don´t know if this will be an actual problem when riding. When you jack the bike off the ground the suspension drops. It is not really play or the suspension being too soft, but more like the linkage comes to a ´dead´ point and the weight of the wheel makes it go past it.
The weight of the bike easely pushes it over that point again, so it just does that when there is no weight on the rear wheel.
Btw, when there is no spring installed and you push up the swing arm, the linkage turns the wrong way and locks up, halfway.

I have two limiting factors where I can mount the top support for the shock absorber.
1. The bolt has to be able to pass the frame,
1. The tube to the reservoir should be clear of the frame.
The latter was only possible by offsetting the mount to the right a bit. I checked that the shock absorber can move freely, this was not a problem.
This shock is far from new - I am considering buying a replacement without external reservoir. But that will have to wait - it will have to do for now.

After close examination of the monoshock I saw the position of the framemount for the link is the problem. Very difficult to reach, so I had to start from scratch. I stripped the bike and redid everything. Here where the link is attached to the frame.

Mount for the shock on the frame, with reinforcements.

The ruler is the line through the sprocket on the engine and the pivot point of the swingarm. (the red line in the gif above)

swingarm in lower position.

swingarm in upper position.

A closeup of the link - forces are now straight on the big bearing - eliminating the ´dropping´ problem I had before.

swingarm in lower position.

swingarm in upper position.

The little bearing in the link, frame side mount, had a little play. I had to order it from Suzuki, as it is not standard. It came at a staggering 46 Euro. I feel ripped off!

I hope I can close this chapter now. I am quite happy with it. Let´s hope I don´t come across any problems lateron.
One little thing - because I use a 17 inch wheel, instead of the 18inch wheel in the original GSX1100, I can move the rear wheel a little bit closer to the engine.

As I don´t have a drill that size that will fit the handdrill I had to improvise. I made a little thingie to make sure I could make a nice round hold.

Then use a hacksaw to remove the rest of the material - and finish it off. I can now move the rear wheel 40 mm to the front more - giving a shorter wheelbase (and chain). Next thing is check where the wheel will end up exactly when I shorten the chain.
Then I can see if I am going to hacksaw a piece of the end - it will probably look better.