GS500 Dual Sport Project

I've been holding off starting this post while I was waiting to make sure I had something that would come together. After some wrenching tonight, I'm committed and know that this should work.

After a lot of research, I decided that a GS500 would be the optimal bike to convert: relatively light, modest power, SIMPLE, cheap, bullet proof power plant, 2 into 1 exhaust, a huge following, plenty of parts and there are thousands of them. I wanted it to land somewhere between a DR650 and the Wee in all respects: weight, off road ability, on road ability, etc. This isnt a woods bike, instead it's aimed squarely and fire roads and double track, things like the trans mass trail and the PDR. Basically the same reasons that the KLRE650 is becoming a popular project. Finally, it had to be doable on a tight budget. I've already got a second bike (Triumph Thunderbird 900) and saving for plenty of other things, so the target is to get this done for $1000, including the cost of the gs500.

Rattonshaw's converted bike is really what inspired me to get going. He's been very helpful sharing some details. HIs bike is below:



So on to the plan and where I am now. So far, I've acquired an entire 2006 DR650 front end including the 21" wheel from a member here. I've got the GS500 pretty stripped (sorry no before pics). Here is the root of the conversion: a comparison of the steering stems, the smaller one being the GS500. I'm going to have a custom stem turned down from 7075 alu to fit the DR650 top and bottom triples but use the stock GS500 tapered bearings and obviously fit in the GS500 headstock. I'll be running a Vapor Tech computer in place of the stock gauges.



Here's a terrible shot of the stripped GS500. It's a 1993 with only 4500 miles on it. Sat for years and needs some good paint and cleaning up. I trailered it home after a 7 year slumber and had it running the next day. It was staggeringly inexpensive for a complete bike. It's a bit rough, and has clearly been gently put down at some point, but it was a deal. An ounce of marvel oil in each cylinder, cleaned up the plugs, cleaned the carbs, jumped it and it fired right up!



The tank leaks a bit at the seams and needs to be sealed. I'm looking for input on people's experience with Kreem and POR 15. Right now I'm leaning towards the POR 15 treatment, mostly because of the lack of MEK and that I've used normal POR 15 before and that stuff is amazing.

I'll get some better pictures but it's late and cold here. For the rear, I'm going to start with the GS500 wheel. An SV650 gen 1 shock bolts right up. It will give about a 2" lift in the back and about 5" of travel, and I'll adjust from there by shortening dog bones. There are plenty of dual sport tire options for the 17" rear wheel. The forums at gstwins.com have been a wealth of information for this project.

Ultimately, the DR650 swinger is supposed to be a bolt up, but some significant modification is required to get the stock DR650 rear shock to fit. The stock lifted rear will work for now. The biggest down side out of the gate is the mismatched wheels, but I'm happy to let that go given the promise of utility vs. cost here. I think this could be a great machine.

This is a winter project, so progress may be slow at times. I'll do my best to keep this up to date. That's all for now. Next steps are to press out the DR650 stem and get the new stem made up, so things will slow down until thats done.

FANTASTIC!!! I think these are one of the best "dual sport" bike out there! I have lusted over Rattonshaw's bike for a long time!
Like you said bulletproof, cheap, and they can make really good power too! I have a friend with a bored, and stroked GS500 (now 676cc) that is almost 90hp. Not really a reasonable gal, as this took a 4 valve conversion, and custom built crankshaft, but getting almost double the stock HP is doable!
Good luck with the build, avoid kreem, and have fun!

So the later DR650's used a 30mm ID top steering bearing. I had assumed it would be a 25mm like the earlier models. Oops.

This isn't a huge deal but it would have been easier if it were an earlier model DR650 since the GS500 uses a 25mm ID upper bearing. The OD for the GS500 bearing is 47mm. The only reasonable ISO taper bearing that has an OD of 47mm has an ID of 25mm, so I'm stuck with that dimension.

The problem is where the top triple slips onto the top of the steering stem. The stem is a slip fit at 25mm where that joint occurs. That's good and bad. It's good because I can still slip the 25mm bearing over that portion to where it needs to be. It's bad because it doesn't leave any room for me to cut threads for the castle nut (which holds the bearing in place).

So, my first thought is to turn down the top triple tree/steering stem joint down to say 20mm and use a bushing with an OD for 25mm and an ID of 20mm. So assembly would be steering stem in from bottom, top bearing from top, castle nut, bushing, top triple and bolt.

(The later DR650's used a nut over a threaded stem to hold the top triple on - maybe they all did, I'm not sure. I already know I'll have to ditch that and tap the top of the stem for a bolt to hold the top triple on.)

Seem reasonable? Any foreseen issues with using a bushing in that space?

Also, since this is becoming a reality, I need a name for this creation. Suzuki 500 G/S maybe? GS500ADV?

Hard to visualize exactly your problem, but I think I get it. Can you post a pic?

Are your forks conventional or usd?

could you swap the stems?

With a lathe anything is possible..

This will be interesting....
I have been looking at the GS500 or ER-5 to
build a duel sport side car hack..

I'm looking forward to seeing one converted here.

I have used both, Kreem sucks! POR15 tank sealer is a very good product. Like with most things follow their directions, take your time and don't try to rush the job (plan on it taking most of the day). If done right the results are awesome.

BTW, neat project. Why no wire rear wheel?

Thanks for the feed back on the POR 15. The issue I was having with the top bearing is hard to visualize and no chance to get pics today. Long story short, having to use a 25mm ID bearing messed with everything ABOVE the the top bearing, including where the top clamp mounted.

Luckily, after a few phone calls, I was pointed in this direction. http://www.twfracing.com/PartsPages/steeringheadbearing.html

These guys modify a readily available (in germany) 30x48x15 to 30x47x15. They use them to run GSXR USD forks in the SV650. Perfect for what I need. So, in the end, I'll be able to essentially recreate the DR650 stem, just make it shorter. No redesigning needed.

To answer a few questions:

I'm using stock DR650 forks, so standard not USD.

Also, as to why no rear wire wheel. I'd like to, and plan to at some point, but not right off the bat. To use the wire wheel, there are 2 options. 1 - use the rear DR650 swinger, which is supposed to bolt up, but results in significant challenges with the length of the shock. or 2 - modify the rear wheel to fit in the GS500 swinger. this is doable, but requires a good amount of machine work to do. Most stock DR650 parts are cheap; however, the wheels are not. In terms of keeping this on a low budget, I've opted to start with the cast wheel.

Still a possibility, but I'm concerned about pressing a steel stem (GS500) into an aluminum triple (DR650). Concerns range from breaking the aluminum triple to the galvanic reaction between the 2. Isn't steel in aluminum a bad idea? any thoughts?

Also, the GS500 is welded in, which is just a pain. When I get them both pressed out, I'll get a mic on them and see if the stem swap is an option for future reference.

My fz1 was steel stem in aluminum triple. The galvanic reaction is overrated on a bike, maritime environment sure.

If you turn the steel to press fit in the dr triple it should be fine. I'd freeze the stem and gently heat the triple. Mine went together easily

G'day,

Excellent choice I reckon, please keep us posted with how you get on. Do you know of any other dirt builds with this motor?

Cheers,

Adrian

Excellent project. I've had a boner for rattonshaws bike since I saw it. It fitst my needs quite perfectly. In the process of getting enough $ together to buy a reasonably nice runner to convert.

I'll be following this thread for sure to see just what it takes. Seems pretty straight forward so long as the earlier forks are used. I like the later forks, or even drz forks (direct swap to late dr650) better, so this is good.

None that I know of. I've wondered a bit if anyone has set up a DR650 with the 500.

I made a bit of progress on the build and got both stems pressed out.

My buddy let me use his press 12 ton press. It wasn't bad, but had to grind off way more material than I thought from the GS500 stem. Also, we bent the bottom GS500 yoke pretty bad. Luckily it doesn't matter, but anyone reading this for info on the GS500, be careful.

top stem = GS500 - press fit diameter 30.0mm
bottom stem - DR650 stem - press fit diameter 30.3mm

I had hoped to press the GS500 stem into the DR650 bottom yoke, but that's not going to happen since is a smaller diameter. Having a new stem machined is next. For what it's worth, I think this would be really straight forward with an earlier DR650 front end.

Sweet! Love the GS500 and thought mine was a great gravel runner stock, with those skinny little tires. My 93 had progressive springs and absorbed small bumps with aplomb.

I like it. I've been thinking about this same thing too.

Bitchen! I was thinking the same thing. I think there are front ends that might have fit in there fairly easily. I've swapped a few out over the years on various projects and between spacer and creative bearing swaps I've been lucky and am yet had to have to press out a stem.

i used to be of the same mindset - hunt around until i found the forks that had the lucky combination of right stem length AND correct bearing diameter to fit whatever frankenproject i was building. ran into a brick wall on my last two projects in that regard. one was swapping a kx500 front end onto the faux rallye xt600, the other was swapping some new 50mm marzocchis and a husqvarna triple clamp onto my aprilia rxv550. in each case, the stems needed to be swapped, and in each case doing that reduced the bearing sourcing, machine work and headache time involved by a factor of about a million.

Stem bearings.....


http://www.allballsracing.com/index.php/forkconvertion


Axle diameters....


Rear: http://scandalon.com/2009/06/motorcycle-rear-axle-diameters/

Front: http://scandalon.com/2009/06/motorcycle-front-axle-diameter-chart/

The AllBalls site is a HUGE help. It's shorcoming is that it doesn't list stem lengths, but It did help me figure out which bearings to use for my Ninja/KLR/KL conversion (someday!). Turns out the Vulcan 500 stem bearing kit has the exact bearings I need for mine.


Have you thought about having weld in cups made? That way you could just lengthen the steering head on the GS frame and use the DR stem, bearings and triples without modification.

And you might look at using an RM-Z/RM-X rear suspension. I've seen them swapped into DR650's and they have a much better ratio than the DR.

I ended up with the DR650 front end thinking it would an easier swap based on the info I had at hand. Once I got it, I realized that the later DR650 didn't fit as easily. Either way, I decided to keep what I had bought and use it. Also, any other dirt front end that would fit with the GS500 frame with minimal mods probably wouldn't be beefy enough to handle the bikes weight or have good enough brakes. The DR650 was perfect for that.

Pressing out the stem really wasn't a big deal. It's much simpler to turn a piece of aluminum stock into a stem than it is to machine and weld a head stock extension, IMO. Also, by machining a stem an using that SV650 bearing I referred to earlier, I can keep all of the stock dimensions of the DR650 stem, just make it shorter. That's easy directions for the shop and peace of mind for me that it's going to be strong enough.

Thanks for the heads up on the rear susp. When I get to that point I'll check it out.

You've seem this right?

Webber Rallye Twin