Suzuki GS650 Monoshock Conversion Cafe Racer

[Dennis]

I decided to try posting progress pictures of the GS650 Monoshock build. 

[Donovan]

Dennis looks great.  I wonder how it will handle.

[fj1200]

I was thinking more about "pinch points".   

[Dennis]

First big "oops."  I chose the geometry for the monoshock based on the bike being on the center stand, and the wheels on the ground.  I think I should have had a board or something under the rear tire (normally, the bike on the centre stand would lift the rear off the ground).   My thought was that the shock would compress quite a bit when I rolled it off the centre stand, plus I wanted to change the over all geometry slightly.  The stock bike was a cruiser, and I want a bit more aggressive geometry.

It turns out that the shock in its present adjustment, hardly compresses at all.   I am going to try loosening the pre-load to see if I can squish it down, but right not I have way too much height.

[Rusty Bucket]

There is a non-linkage monoshock at the shop, I think from a Seca 400.  How long is the Ducati shock you have now?

[Dennis]

The Ducati monoshock is exactly 12" from eye to eye, as it is currently set.  The pre-load is cranked up pretty good.

I went to Princess Auto to get a tool to loosen the big threaded pre-load adjusters, but it was closed.  Imagine that, on Boxing Day.  Oh well.  I still want to try loosening the pre-load before I look into a new shock or cutting my welds and moving the top mount further up in the frame.  The close up picture of the shock shows that I have more than an inch of adjustment.  If loosening the pre-load actually shortens the shock, I should be fine.

[Dennis]

A couple of weeks ago, I welded in the tubing for the seat and rear.



This weekend was productive.  I spent almost all Saturday fabricating the rear brake set up.  I was looking at used rearsets on Ebay, but in the end decided I want to keep to my theme which is "lo-buck."





The battery is supposed to be able to sit on its side.  Once its filled and capped, it is supposed to be permanent and spill proof.  I am counting on that.





I was worried that the seat was too high, but now I think it looks pretty cool.  Russ helped me loosen the pre-load, so now when I sit on it, it drops a bit.

[Dennis]

I just stumbled upon someone else's version. 

http://3onthetree.wordpress.com/2011/06/

[Fritz]

Last pic looks Good...Lowering the shock improved the stance to my eye....
That Rusty Bucket is like an Aleister Crowley of Motorcycles......
Looks like you are having fun with that bike.....

[Rusty Bucket]

Your swingarm is triangulated and I have no qualms at all about it's strength:  that guy's linkage-style swingarm at least looks like it might want some bracing, even if just to protect the driveshaft components.  When Honda started building the same style linkage set-ups they used a rectangular box-sectioned steel arm that gave the appearance of being a big beefy piece.  Check out Mike McLintock's Pro-Link CX650.

[fast1]

even with the lessened pre-load the geometry you have along with what I believe is too much shock is gonna make this thing try to "buck" you off on every bump. Be sure the fairing/ dash is not to close to your face or you will be kissing it! Shorter or lighter shock, or at least a lighter spring would help. Thought about early Virago monos?? Should be able to make it hop and skip all over on a burnout.  Maybe cut 1 or 2 coils off the spring......

[Dennis]

I got a pair of 16" tapered mufflers and tried just putting them on where I cut off the old mufflers.  The look just isn't right.  The straight line from the exhaust through the mufflers would look fine on a more traditional styled cafe racer, but not so great with the monoshock and mags look.  I had previously thought that if that failed, I would bite the bullet and buy a new 4 into 1 Mac system.  The problem with that is threefold (1) with shipping its $400 (2) they are all chrome, and I prefer flat black and (3) I like to see everything in place before I make a committment, and if they end up looking wrong, then I am stuck with an expensive exhaust system that I'd not likely be able to resell.

My present brainstorm is to fabricate my own system from scratch.   This would be a great challenge, but I might be biting off more than I can chew.  Especially difficult would be the section where all four pipes come together.  In most aftermarket 4 int 1s they collect from four smaller (1.5") tubes into a larger tube which then goes to the muffler.  If I do this I will need to buy at least two bending dies which I don't have and they are expensiive ($226 for the 1.5" die and over $350 for the 2", before shipping ... ouch).

Query: does anyone have an old set of 4 into 1s from a 750cc or smaller, UJM (universal Japanese motorcycle)?  It would be far easier for me to modify some existing pipes rather than fabricate everything from scratch.  No muffler is needed as I will either use a modern can, or make my own.

[Fritz]

This one may be too Ratty....KZ650....

[Dennis]

Thanks Kurt.  I am thinking from the pictures those may be past their "best before" date.   After we chatted on the phone Russel assured me that fabricating my own 4 into 1 collector piece is easy.  He drew pictures, "nuthin' to it," he assured me.    Of course, Russel is the club's master craftsman so I am sure what he says is easy is another person's nightmare.  His confidence is inspiring though.

I'd still like to have a look at them,  and see  in the flesh (steel/rust) what the picture doesn't show. 

[Dennis]

I purchased a 1.5" die for my tubing bender in anticipation of making my own exhaust.  I did a sample bend last night with thin wall tubing and it bent just fine.  The big problem is the bend radius to too large for the tight bends needed.  Damn.  So close.

I am going to take one last stab of utilizing the 4 into 2 in some tasteful way before I simply admit defeat and buy the Mac chrome 4 into 1. 

I have a date with my man cave tomorrow for the full day and evening.  After the exhaust I will be working on mounts for electrical components, fabricating the seat pan, and mounting the whole she-bang.  Anyone interested is welcome to drop by.

Peace and Grease. Dennis