gs1100gk 41mm straight leg forks as performance mod for gs750/850/1000?

[Chuck78]

I just happened to read a mention the other day on here about the existence of some 41mm GS forks that came on only the full on bagger touring version the GS1100GK. The standard 1100e & 1100g all had 37mm forks. The bagger was made to carry lots of touring cargo + passenger, so it came with the most stout forks of any Suzuki GS that I know of.

Well it just so happens that a week after reading about those, I tried to dismantle the gs850/1000 forklegs that I thought I had scored 2 weeks earlier for $20, chrome looked great surprisingly, not a spec of rust anywhere, but had been sitting outside for years. I drained the oil out to find some water had gotten in past the seals.

Upon trying to dismantle, I instantly realized that the damper rod bolt that is supposed to be 6mm on 550/650/750 forks & 8mm on 850/1000 forks was actually 10mm... Didn't take me long to reach for the calipers to measure these 41mm beasts...

These are dual disc straight leg forks, tarozzi makes a brace for them, they can run salty's twinpot 296mm ninja/Honda CBR dual disc mod brakes, only caveat is the spacing isnt the 175mm (that I can barely squueze a 110/90/18 into with zero room for a fender), nor is it the 185 width that is darn near perfect, the triples are 204mm spacing. I don't have any here, and I suppose you could run gsxr triples, but then the center section of the tarozzi brace doesn't fit. Best stick with 204.

Has anyone considered running these low cost forks as a performance upgrade, or are they going to be substantially heavier than a modern 41mm fork? Seems like a consideration to think about. Now if I only had some triples to clamp this thing in to get the top caps unthreaded. Impact gun broke loose the damper rod bolt but now its just spinning...

 

[Guest]

I've got those forks on my '79 850. I don't think they are much (if any) heavier than the 41mm forks from a gsx600/750f (newer katana) I had a set of those on my '83 750 for a while. 850 style fender fits if you spread the mount out a little, i have the twinpot mod on it, i had to place the flat steel pieces to the inside of the forklegs, have worked fine for two years now. The rubber handlebar mounts are great, i've got spacers on mine to raise the daytona style renthal alumninum bars slightly. No bar vibes whatsoever.

 

[blackhammer]

Hey Chuck, i have a set of these on my 80 1100E project that Ozman gave me a tip on from a wreckers a while back. Came across your posts on the 41's whilst searching for options on replacing the standard top and bottom triples. Have you actually tried newer GSX triples?

 

[GregT]

They are actually quite desirable as race forks for those of us around the world who must use forks from the period on our race bikes...

I know where there is a very ratty GS1100G local to me - and i'm waiting to see if the owner is going to part it out.

 

[gs58]

I had a pair of these 41's on my race bike fitted with emulators and using GSXR triple clamps. I also had a fork brace fitted that I had made by an aircraft engineer friend. They worked great and were so much more solid under braking than the 37's.

The only difficulty that I had with them was that I could not buy the bushes that fitted on the bottom of the fork leg. I have several sets of bushes that are the wrong size that were sent to me from around the world by people assuring me that they were the correct part but they are all 1mm in diameter too big. Fortunately the ones I had still had some miles left in them, I just wanted to replace everything while they were apart to fit the emulators.

It's a pretty lousy photo but any photo is better than none.

 

[posplayr]

Nice to know, the main reason to go with the gs fork is the fender mounts. With the GSXR forks there is no good way to retain your gs fender. I have soldered on fender lugs once but failed on a second try.

 

[Chuck78]

why not make up a fender that mounts to the Tarozzi fork brace or other fork brace used? The gs500 fork mounts the fender exclusively to the factory fork brace, not the fork legs.

I wonder if any of the racetech bushings/fork tube glides would fit the GK fork? Or if it's possible to take a bushing of the proper thickness but too large o.d. & Dremel slice some material out of the gap and roll/form them to the smaller necessary size? You might need a radiused jig to press form them into the proper curvature. Maybe a long shot.

I think I recall the o.d. of the inner tube getting skinnier at the bottom in the damper rod area, and this is where the problem stems from.

 

[Chuck78]

Hey Chuck, i have a set of these on my 80 1100E project that Ozman gave me a tip on from a wreckers a while back. Came across your posts on the 41's whilst searching for options on replacing the standard top and bottom triples. Have you actually tried newer GSX triples?

No but I measured some triples up at the local vintage Japanese parts salvage business while looking for the GK triples, and found that Suzuki SV650 triples and several GSXR/Katana triples were close to the same width. I was not checking steering stem height vs any of the GS lower triples they had. Someday I may return and do just that.

Seems with the twin pot brakes needing spaced in some, I'd rather go with a 195mm triple clamp or maybe even 185 width, then you could eliminate the need for the hub spacer and/or just run Honda 599/Hornet 296mm rotors that have the 22.5mm offset.

Still, I figured looking at the damper rod a while back that either dome time spent on the tech line with racetech, or else some adapters needing to be machined would be what it would take to fit emulators to these monster damper rods. And then maybe buying the Tarozzi brave and mixing and matching the center sections if they are the same bolt spacing between other models, so that you could get a narrower center piece that worked. Or else have a machinist make up one of those also. Strip & polish the clamp pieces of the Tarozzi brace then.

 

[Chuck78]

Going with some other late 90's/early 2000's Honda forks that run 296 or 310mm brakes may be less hassle in the long run if you want emulators and fork brace. At 41mm though, maybe a fork brace isn't really needed?

I love the Honda forks since they run the 296&310 rotors that we seek out for salty's twinpot brake mod... and that many of those rotors just bolt on to our hubs with just drilling the holes larger.

 

[posplayr]

why not make up a fender that mounts to the Tarozzi fork brace or other fork brace used? The gs500 fork mounts the fender exclusively to the factory fork brace, not the fork legs.

I wonder if any of the racetech bushings/fork tube glides would fit the GK fork? Or if it's possible to take a bushing of the proper thickness but too large o.d. & Dremel slice some material out of the gap and roll/form them to the smaller necessary size? You might need a radiused jig to press form them into the proper curvature. Maybe a long shot.

I think I recall the o.d. of the inner tube getting skinnier at the bottom in the damper rod area, and this is where the problem stems from.

The whole point was to retain a stock fender and not have to use fork brace style mount.

This was the jig I made up to fabricate the mounts that were brazed on with a special aluminum alloy rod.

Finished product, 1988 GSXR 1100 41mm fork/triple but modified with fork mounts to retain stock 83 GS1100E fender, but the GSXR fork brace. The OEM fender mounts are a PITA and my second attempt even failed. So these 1100G 41mm forks would avoid that hassle and with emulator (as I have as well) are probably comparable. BTW my anti dives are from the ED but non functional(fit in place of the GSXR anti dives).

 

[blackhammer]

I've sent the standard top triple off to have a new one machined up after spending a fair bit of time at the local wreckers trying to find something that works.

I was able to get the standard GK axle, caliper mounts and spacers when i got the forks, so everything just bolted up nicely with a standard 1000 19" front wheel and speedo drive.

I intended to talk to Salty about a caliper and disk upgrade for these forks. I believe they should work ok if the standard calipers/discs all currently line up nicely.

Interesting thoughts on the honda forks, i hadn't considered that swap as the 41's i had were in such great condition and bolted up so easily. I'll do some searching, i currently have some spoke hubs being built so i was keen to keep the same axle/spacer set up. Changing bearings and spacers might be in the too hard basket.

thanks for the thoughts tho Chuck.