GS850 Streetfighter

[Indy]

First off, a big thank you to wringer. He helped me big time disassembling the bike. It's down to the frame, pics to come.

Anyway, plans for it, with some questions on how to attain these plans.

I've been thinking of ways to mod it, my only regret so far is that it's a shaftie, which means pretty much any 'cheap' way of swapping swing arms and going to a monoshock seem unattainable.

But, I do want to go with an updated front fork setup (GSXR type), and I'll be doing some tank swappage. (Looking at figuring out how to put an 1100e tank on it). It's going to be a single seater, so the rear fender is going to be 'small' and compact. Like the picture.

So, what forks/fender/etc would the group suggest?

Kind of 'free forming' this, since it's my first foray into a custom(ish) bike. Anyone have any ideas that they would like to see done? A 'group' project. LOL

Thanks in advance... I'm out.

[80GS1000]

What are you trying to gain by doing these mods? Is it for looks, performance, or a mix of the two?

That shaft drive will make life a bit more difficult. Find out if maybe a GS1100 shafty swingarm will fit in your frame, and if the shaft will line up with your motor once installed. If so, you *may* be able to put a 4.5x17" rim on the back, which would get you a 160 radial on the back. That is, if the shaft doesn't interfere.

Standard front upgrade for GS's is a 89-95 GSXR 1100 front end. Bolts right up, no fuss or muss. Better brakes, lets you run a radial, and stiffer forks. If you can't do the back end with a radial, don't bother with the upgrading the front since mixing radials with bias ply tires can be dangerous.

If the shaft drive prevents you from upgrading the rear suspension, the next best thing to radials on these bikes IMO is a set of Pirelli Sport Demons - very sticky.

Keep us posted on how you get on.

[bwringer]

I was happy to be of assistance!

Besides the obvious functional advantages of the shaft drive, I happen to think a nice polished rear drive housing looks about 1000% better than a greasy, nasty old chain. If you search around for "BMW Cafe Racer", you'll see lots of proof that a shaftie can look extremely cool.

Anything is possible with enough explosives and a welder, of course, but I'm not aware of anyone who has successfully transplanted a wider rim onto a GS shaftie. A wider tire is obviously not needed in any way (the bike handles extremely well with stock size tires, and larger tires only hurt handling), but many have asked because they think the 130/90-17 rear looks skinny or something.

Some have stated that a 140/80 tire will fit, but they all end up going back to the 130/90 because it messes up the handling. Bikes are a lot more sensitive to tire size and profile than cars and trucks.

Lots of people have also asked about converting a shaftie to chain drive, but I don't think anyone has been silly enough to try it yet -- it's a lot simpler and less expensive to buy a chain drive bike if that's what you want, since there are so many differences in the engines and frames.

Another approach could be to use a 16 inch rear wheel from an L model GS850 (I happen to have one in my garage you'd be welcome to...). The slightly smaller rear wheel would make the bike sit a little closer to the ground, and a 130/90-16 rear tire looks a little fatter. It's also a much more common size than the 17 incher, so you have more choices in tire brands and patterns.

Here's another thought -- you're welcome to come over sometime and take some measurements on my VX800 -- it has a wider rear wheel wearing a 150/70-17 radial, which looks nicely meaty, and the driveshaft system is virtually the same as my GS. I know for a fact that the VX rear wheel will mate right up to a GS850 rear gear (yes, I got bored and tried it with a spare rear gear), so who knows what parts might mix-n-match? Of course, the VX800 is about 10 times more rare than the GS850, so finding a donor bike would be a huge challenge (you can't have mine...). The VX forks are nice 41mm units (GS850 forks are 37mm), but the single front disk is admittedly rather lame. The brake is barely acceptable on the VX, but would be overwhelmed on a GS that weighs 80-100 pounds more.

A nice upgrade to the front end would be the braking system from a 1980-83 GS850 or larger GS model -- the slotted rotors and improved calipers and master cylinder will improve braking dramatically over your '79's solid rotors.

Personally, I'd be inclined to keep it looking light and stick with the correct tire sizes. The '79 wheels are cast in a different pattern that I think looks much better than the later wheels, and would look really cool powdercoated black or a bright contrasting color like red or yellow. Paint or powdercoat the fork legs black, chop the fender (or remove it entirely and run a fork brace) and that would be a really nifty-looking front end.

Add a nice round chrome headlight from CRC2 like the one on my bike, maybe a Buell flyscreen or a cafe fairing... http://www.omarsdtr.com/fairings.html There are also a few companies importing some really wild fairing/headlight units from Europe if you want something wicked and evil looking.

[Indy]

Brian, what have I told you about 'chrome' or shiny things in general? lol

Yea, I'll have to take a look. Right now, just weighing my options, looking at a lot of pictures, trying to determine what I like, and what I don't, and really, why I don't 'like' a certain thing.

I'm really kind of just using this as my 'first' (practice) bike, not only for riding, but general maintenence, discovering the 'inner workings', and a little light customizing. (It didn't help that my son and I went to the Triumph dealer and I sat on a brand new Speed Triple, which is what I really like in a bike. Not a buttload of plastic, just motor). BTW... those fairings are butt ugly. LOL

So, I want something that I can work on and do what I like. Lord knows my wife would kill me if I bought a 'new one' and started tearing it apart and cutting off stuff. LOL

All that said, I want to do this all 'once', and be happy with it, hence the questions and the research.

-------------

Back to the topic.

I don't like the backend 'cafe' style that alot of guy have. I admire the work, in fact, I think it's awesome and some of the techniques will be employed, by I don't like the back portion (sticking up) rear fender. But I do know that I want it lower than stock, and like the look that 80GS1k has with the front end. I think that fits nicely into my over all 'look' that I'm trying to achieve, plus it has the added benefit of performance, which I have always been a subscriber of (don't add anything just for looks, looks are secondary, performance is primary).

I think the three things that I can easily (cheaply) do are a tank/fork swap, and some new fangled rear fender design. That should achieve what I am looking for both in performance and appearance.

One thing that kind of stood out from 80GS1k's post was this:

If you can't do the back end with a radial, don't bother with the upgrading the front since mixing radials with bias ply tires can be dangerous.

Are you meaning that I shouldn't do the fork upgrade? Or just the tires?

I think that's it. LOL

[80GS1000]

One thing that kind of stood out from 80GS1k's post was this:

If you can't do the back end with a radial, don't bother with the upgrading the front since mixing radials with bias ply tires can be dangerous.

Are you meaning that I shouldn't do the fork upgrade? Or just the tires?

I think that's it. LOL

A bit of clarification. The limiting factor seems to be the rear end of the bike, particularly the shaft. If it turns out you can't mount a wider rim made for a radial on the back due to the shaft, then you should NOT mount a front end that is made for a radial tire (ie GSXR 1100), because mixing the two types of tires on the same bike can lead to dangerous handling properties which could make you crash. If you you CAN put a wider rim made for a radial on the rear of your bike, then by all means put a GSXR 1100 front end on and enjoy the better brakes, the radial tire, stiffer forks etc etc.

A bit of experimentation with a GS1100 shafty swingarm and a 4.5x17" (2000ish Katana 600) rim may be in order.

If it turns out that you can't upgrade the back, then think about maybe swapping front ends from a sportier GS model. It'll bolt up no problem, and then you can get some sticky bias plys on the front and back like the Pirelli Sport Demons or the Bridgestone BT45's.

[bwringer]

The swingarms and tires are identical on all 79-85 GS850, GS1000, and GS1100 models, so that's not going to get you any width.

Besides the 90-93 VX800, the "other" early-'90s Suzuki shaftie with wider wheels was the 91-93 GSX1100G. However, both this bike and the VX800 are VERY rare.

Since then the only Suzuki shafties have been the Intruder 750, 800, and 1400 cruisers. The rear wheels are spoked 15 inchers with drum brakes, probably no good for mounting radials.

http://motorcycles.about.com/cs/makesandmodels1/p/04suzvs800glk4.htm

[Mike_H]

As far as the rear fender is concerned, you can graft a new fender to it, and lower the fender on the frame, to give the appearance that the bike is lower than it really is. I am doing this to my 650, (see link http://www.thegsresources.com/_forum...d.php?t=101452). I will be posting a "how-to" article soon. The read fender you have right now doesn't look to bad, IMHO. Kinda gives the bike a flat tracker look, which is not a bad look to have. Keep with it though, nothing better than having someone complement your bike, and being able to tell them, "Thanks, I did all the work myself."

[80GS1000]

The swingarms and tires are identical on all 79-85 GS850, GS1000, and GS1100 models, so that's not going to get you any width.

Besides the 90-93 VX800, the "other" early-'90s Suzuki shaftie with wider wheels was the 91-93 GSX1100G. However, both this bike and the VX800 are VERY rare.

Since then the only Suzuki shafties have been the Intruder 750, 800, and 1400 cruisers. The rear wheels are spoked 15 inchers with drum brakes, probably no good for mounting radials.

http://motorcycles.about.com/cs/make...zvs800glk4.htm

The swingarms and tires are identical on all 79-85 GS850, GS1000, and GS1100 models, so that's not going to get you any width.

I respectfully disagree at least as far as chain drive models go - the later chain-driven GS1100 swingarms were wider and made of aluminum (much lighter!) compared to the GS1000/850 swingarms, which lets you mount a wider rear rim and tire. Were the shaft drive model swingarms all the same width?

Check out RJ's GS1100E with a second gen GSXR 5.5x17" rear rim and radial mounted.

If the shafty 850 and 1100 swingarms are the same width, then this point is officially moot.

A wider tire is obviously not needed in any way (the bike handles extremely well with stock size tires, and larger tires only hurt handling), but many have asked because they think the 130/90-17 rear looks skinny or something.

Some have stated that a 140/80 tire will fit, but they all end up going back to the 130/90 because it messes up the handling. Bikes are a lot more sensitive to tire size and profile than cars and trucks.

Yes and no. Installing wider tires than intended on stock rims, such as a 140 radial on a stock GS rim, is a bad idea because of the change in tire profile, which will adversely affect handling.

At the same time, if you install the hardware appropriate for radials (wider rims, newer forks), you'll see an improvement in handling.

Have you ridden a modern sportbike lately? Their high speed, high angle cornering stability and ability (http://teamsuzuki.com/RoadRacing/Pho...llsize/AY6.jpg) in part stems from the large contact patch those wide radials provide in the corners. Their shorter forks also significantly quicken up the steering by increasing rake and decreasing trail. So, you get faster steering AND better stability when leaned over. And you can take the corners MUCH faster than on skinnier tires.

[bwringer]

If the shafty 850 and 1100 swingarms are the same width, then this point is officially moot.

Yes, the 850 and larger shafties are pretty much mechanically identical except for the engines. The swingarms are the same. And, in fact, the engines can interchange easily -- a few people have transplanted a 1000G or 1100G engine into a 850G chassis with excellent results. Of course, I'm leaving aside the usual detail and cosmetic differences between the G and GL models and years.

I know someone's going to bring up this next detai, so I might as well address it now... yes, I'm aware that the wheels on later shafties are a wee bit wider. The recommended tire sizes are the same for all: 100/90-19 front, 130/90-17 (G model) or 130/90-16 (GL) rear . And then there's the whole tube/tubeless confusion surrounding the wheels on e some early shaft drive models, but I'll leave that out.

Installing wider tires than intended on stock rims, such as a 140 radial on a stock GS rim, is a bad idea because of the change in tire profile, which will adversely affect handling.

At the same time, if you install the hardware appropriate for radials (wider rims, newer forks), you'll see an improvement in handling.

I agree with the above completely, and never meant to imply otherwise. If you have the stock rims, you'll screw up a fine-handling machine by simply stuffing wider tires onto the rims and causing the tire's profile to get all pointy and weird.

I agree that modern tires, forks and brakes are pure magic and look really phat and cool when tacked onto 1970's frames. Nothing morally wrong with that. Swapping forks is relatively easy, of course, but getting a wider rim into a shaftie would be a challenge.

I'm thinking it may be just barely within the realm of possibility to find components from later shaftie Suzukis that might, possibly, maybe could be squeezed into a GS850 and thus give you the wider rim. The problem is that 99% of the later shafties sold were Intruder cruisers, which may not make suitable wheel donors.

Simplest, of course, would be a wheel transplant, but you may also need the swingarm and modifications to the frame and driveshaft.

I think Rich and I will have to do some experimenting and measuring with my VX800 and GS850... we're getting pretty stir crazy here in Indiana.

[Mike_H]

My buddy has a M50...I think that has a shaft drive. I know it has at least a 160 rear on it, It may be as big as 180. His front is a 130. I oughta take some measurements next time I'm over to his place. The frame is MUCH wider on his M50 so it's probably NFG, but I'll take a look.

[kingofvenus]

There are places that can widen rims, my old 1100 honda drag bike had an early cbr 600 rear wheel on it that had sent to such a place by the previous owner. Had wider outer rim sides welded to the center section.

[Indy]

There are places that can widen rims, my old 1100 honda drag bike had an early cbr 600 rear wheel on it that had sent to such a place by the previous owner. Had wider outer rim sides welded to the center section.

Yea, Brian and I were discussing that very thing off line. The big question of doing that however is how wide is feasible, and what size tire would that afford.

Going to be working on it this weekend, we'll see.

[80GS1000]

Yea, Brian and I were discussing that very thing off line. The big question of doing that however is how wide is feasible, and what size tire would that afford.

Going to be working on it this weekend, we'll see.

Probably the best way to figure this out is to measure how much clearance you have between the tire and the shaft right now. Based on that measurement, you'll know how wide you can go.

[zeroaffinity]

Thanks for this thread. I have a 1980 GS850G ... at least I thought that until just now. See, there is a 16" wheel on the rear. I knew a 17" came with the G, but had no idea why a 16" would be there now. Just saw that GL's came with 16's.

I bought a 17" off of eBay for cheap and I want to mount it. (Got a rear rotor on the way too.) Anyway, will the 16" and 17" wheels mate up to the same swingarm or is there a chance that these aren't compatible?

If so, what kind of workarounds would be available?

[Chris Bohane]

Personally, I'd be inclined to keep it looking light and stick with the correct tire sizes. The '79 wheels are cast in a different pattern that I think looks much better than the later wheels, and would look really cool powdercoated black or a bright contrasting color like red or yellow. Paint or powdercoat the fork legs black, chop the fender (or remove it entirely and run a fork brace) and that would be a really nifty-looking front end.

As suggested so you can see what the front might look like. Powdercoated black wheel, black mudguard and forkbrace.

http://i74.photobucket.com/albums/i276/201156/TrikeBarrelRECustomShow286.jpg

Good luck
Regards
Chris