GS500 Dual Sport Project

[Chris S]

Hi Adrain, the pic should be fairly self explanatory
Top shock is standard
Yellow shock is SV with a hole drilled an inch higher up the mount.
Lifts it a couple of inches

C

Pic of near-finished bike here:

[Adrian V]

Thanks Chris, that's pretty clear.

Does anyone know if any more radical alternatives have been tried? I'm wondering if given that the swing arm from the DR650 will fit, whether that gives additional alternatives for more suspension travel, perhaps from the DRZ400 or RMX 250?

Just wondering, could be way off the mark here

Cheers,

Adrian

[Bleached]

Originally Posted by Chris S

Check out my what I call my 'GSR500' here.
Been at it two and a half years, but only the back wheel and gearing to sort out now.

DR front like you, but 19" Excels both ends like a flat tracker, so one spare does both. (I watched On Any Sunday at a vulnerable moment ;-)

Have you heard of the SV650 shock trick? Get's the back up to match a DR front end.

Good luck with your build. Looks like you're working it all out.

There are some terrific machines in this SARequired section - my sorts of bikes!

Chris S

this is great! good to know that someone else out there has taken this path and found the little 500 to be the right choice. I had planned on using the SV650 rear shock. I didn't realize that you have to drill it out, so that's very good to know. In addition to the lift, I think it also gets you about another 1.5" of travel.

Since I think its pertinent here, and I'm curious, can you share the details of your front end swap? It looks like you used the earlier (Pre 95?)DR650, which from what I've found, should be pretty straight forward.

To answer some other questions, I did think about welding material to the GS500 stem, but couldn't do that easily myself. In the end, I have the ability to have a new stem CNC'd pretty easily, so I'm taking that route. here is the model just for reference of the DR650 stem shortened for use in the GS500. we should find some time to get it turned in the next couple weeks. I have the actual solidworks file as well. If anyone needs it, PM me and I can email it over.



Also, good to know on the DR350 rear wheel. I'm kind of looking at the rear, aside from the shock, as phase 2.

A few thoughts on design of the stem: I purchased 12" of 1.25" 7075 T651 aluminum. It's a heat treated, stress relieved, high strength aluminum. The drawing shows it hollow, but I plan on leaving it solid. It's 17mm shorter in length than the original DR stem, and I'm using the same OD's as the DR650, so it theoretically should have a better column strength and be generally stronger. If anything, it's the neck of the frame that might experience an increased load.

I'll get some pictures of the finished part once we're done.

[Bleached]

Originally Posted by Adrian V

Does anyone know if any more radical alternatives have been tried? I'm wondering if given that the swing arm from the DR650 will fit, whether that gives additional alternatives for more suspension travel, perhaps from the DRZ400 or RMX 250?

According to Rattonshaw, the first gen DR650 swing arm is a direct bolt up. Challenge is apparently with finding space for the shock.

[ohgood]

oil cooler...
new petcock...
black paint (to hold the headers together)
5 degree advance for fun..
mind your goats and stalwarts syndromes...
and hire a crane to pick it up...

you should be set now !

(subscribed, just for the mammaries)

[JamesG]

Originally Posted by Adrian V

Thanks Chris, that's pretty clear.

Does anyone know if any more radical alternatives have been tried? I'm wondering if given that the swing arm from the DR650 will fit, whether that gives additional alternatives for more suspension travel, perhaps from the DRZ400 or RMX 250?

The SV shock is usually for the stiffer spring and (slightly) better damping.

"Short" of a longer swingarm, you can increase ride height all the way up to the maximum extension allowed by chain clearance with shortened dogbones.

[Adrian V]

I'm curious what the effect of shortening or lengthening the dog bones might have on the rear suspension. I have a KTM 640 and have put different dogbones on to reduce the height a bit (short legs) and this has definately affected the feel of the suspension, as it feels harder initially and bottoms more easily. The concensus as to why this is occuring (if I recall correctly) seems to be that doing this affects the rising rate of the suspension for the worse. I also tried a greater reduction in ride height and the effect was more pronounced, with the shock bottoming way to easily. If anyone is interested I can probably find a link to a long thread about this.

On a related note I think a longer swinging arm would give greater leverage on the shock, but this could probably be tuned out with a heavier spring and a re valve as the rising rate effect would not be compromised (I think).

Anyone any other thoughts about this? At the end of the day I'm just wondering if a bit more travel could be gained and at the risk of offending the DR afficonados, as slightly better fork/shock be adapted to fit?

That said though the DR/SV suspension certainly fits with the ethos of the bike and it's suited purpose, I'm just curious I suppose what's possible with the GS.

Cheers,

Adrian

Cheers,

Adrian

[JamesG]

Changing the dogbones changes the leverage ratios, or rather changes the relative position of the linkage which is connected to the spring, so its force isn't linear. Yeah its all very complicated geometry and some calculus, but luckily is not all that critical unless you are on a race track going 10:10ths. You just have to find a set up that gives you the results you are looking for and then accepting/get used to the resulting behaviors. When you go to a longer link (to lower the arm) is put the arm/shock further on the force curve acting like increased preload (sorta). Going the other way reduces it, which in this application is a good thing, you want softer to take advantage of the available travel, but its not perfect, and any change in suspension requires adjusting/changing everything else.

[Chris S]

Since I think its pertinent here, and I'm curious, can you share the details of your front end swap? It looks like you used the earlier (Pre 95?)DR650, which from what I've found, should be pretty straight forward.

Actually it was a 2003 front end, and in great nick too. Late DR650s are not so common on the UK. We did the same as you: shortened and turned down the stem so the DR triple clamps and bearings fitted onto the GS headstock. To others: try and get a complete front end with wheel, disc, caliper and so on. Little bits like the speedo drive cost a fortune (could not find used, even on US ebay).

I cant recall if we knew a DR650 swingarm would slot in, and if we did why we didn't do it. We've certainly talked about lengthening the GS swingarm (steel), but right now it looks like the 19" will fit.
I dont know the exact shock space complications, but if you have a ready-assembled DR back end with wheel and brake with just the sprocket to line up, that could be less work than lining up the DR wheel/hub/brake in the GS arm (that's being done now).

btw, I recall rattenshaw mentioning the pegs are too far back for easy standing and weighting - they are.
It could be a major ergonomic issue, and moving it all forward is not so simple - is it?

[malokam]

Originally Posted by Chris S

Actually it was a 2003 front end, and in great nick too. Late DR650s are not so common on the UK. We did the same as you: shortened and turned down the stem so the DR triple clamps and bearings fitted onto the GS headstock. To others: try and get a complete front end with wheel, disc, caliper and so on. Little bits like the speedo drive cost a fortune (could not find used, even on US ebay).

I cant recall if we knew a DR650 swingarm would slot in, and if we did why we didn't do it. We've certainly talked about lengthening the GS swingarm (steel), but right now it looks like the 19" will fit.
I dont know the exact shock space complications, but if you have a ready-assembled DR back end with wheel and brake with just the sprocket to line up, that could be less work than lining up the DR wheel/hub/brake in the GS arm (that's being done now).

btw, I recall rattenshaw mentioning the pegs are too far back for easy standing and weighting - they are.
It could be a major ergonomic issue, and moving it all forward is not so simple - is it?

I have a DR650 speedo drive laying around somewhere. If I can find it, pay shipping and its yours.

[GI_JO_NATHAN]

Sorry I don't have the time to read through all of this right now. Just wanted to throw my two cents in real quick. The GS shock is probably a little for off-roading. You can throw in a Katana shock with no issues. You will get more adjustability, and a couple inches right off the back.

[buls4evr]

And remember that if you put a much longer shock on it then you have made a problem at your swingarm pivot/chain run interface. You try to saw your swing arm in half on rebound all the time! Not so easy to match up that countershaft to rear sprocket angle and still consider getting the chain not to hit. The GS countershaft is farther from the swingarm pivot than the DR is too.

[Bleached]

Had a bit of time over Christmas. Here's the finished stem pressed back into the lower triple.



And here is the front end mocked up. It's assembled with the wrong top bearing, and none on the bottom, but it all fits, and looks pretty good! No clearance issues.



The factory steering stops even line up and work properly. Bearings are on order and I'm looking for a first gen SV650 rear shock if anyone has one they want to part with.

[Keith]

Originally Posted by Bleached

...And here is the front end mocked up. It's assembled with the wrong top bearing, and none on the bottom, but it all fits, and looks pretty good! No clearance issues.

That front end looks good on there!

[ben2go]

Digging your thread.I own 4 GS500s and have two spare frames.I have done a lot of mods on my 89 GS.It's designated a GSX500F.

You could have used the katana 600/750 front end, with .95kg or 1.00kg racetech or sonic springs, set static sag around 1/2 inch,and install the forks flush with the top of the upper triple clamp.Most come with 3 position rebound dampening with the selector on top of the fork.This would give you at least 2 inches of lift,adjustable rebound,the ability to run most any Suzuki dirt bike wheel in 17 to 21 inch sizes,and gives you dual brakes that will haul a GS from sub light speed to stop in negative 2.3 seconds.Just kidding, but they stop really good.Did I mention that the Katana front end is about the same weight or maybe a little lighter.The SV650 shock installed straight up without redrilling the hole gives approx. 3 inches of lift.Depending on how you set the preload and how much loaded weight,it will sag from 1/2 inch to 2 inches.I am running 95 Katana 750 front end and rear shock on my GS.The forks are slid up in the triples about 1.25 inches and my CBR F2 clip ons are top mounted.My bike sits about 2 inches higher than stock with the rear shock preload maxed out(I'm fat) and my static sag in the forks set at about 1 inch.I could raise my bike 2.25 inches in the front and under mount my clip ons,but then they would hit my tank.Dgyver(GStwins member) and I did the Katana front end conversion together.We pressed in the GS stem into the Katana triple and welded it up.I run GS head bearings and everthing else is set up like the Katana.I have a lot of write ups on GS Twins and I have a blog about my black bike.When I finish up my "Lite Tourer" project I will start putting it on my blog.
http://maniccycles.blogspot.com/

This is my bike.It is roughly 2 inches taller than a stock GS.I could go up 2.25 inches more in the front by simply adjusting my static sag through longer spacers and lowering the forks in the triple clamps.I would gain probably 1.5 to 2 inches in the rear by installing a stock SV650 shock.Even more if I went with the longer DR650 swing arm.



Just some food for thought.

EDITI should say that IMHO, this set up would give the performance something akin to a V/wee strom or Versys,and be good for gravel running or double track.Your set up will be good at single tack hands down.There is more travel in those forks than the Katana can provided.Maybe more lift if set up with minimum sag.