GS1000 streetfighter idea w/ picture

Anybody know if 93 GSXR750 forks will be long enough for my 79 GS750?

[John Kat]

Here are the lengths of the "older" Suzuki forks:
GSXR K : 740 mm
GSXR J : 765 mm
Bandit : 780 mm
GS 1000 : 775 mm
Katana 1100 : 800 mm
The FJR 1300 fork legs measure 800 mm another potential candidate with GSXR K/L triple trees?

I have tried the GSXR K ( 2nd gen) : too short compounded by the 17" wheel
The GSXR J is just fine with the 18" wheel.
I also lengthened the GSXR K for my 1100 Kat.
Very complex and expensive: not recommended!

http://www.thegsresources.com/_forum/showthread.php?t=188127

[salty_monk]

I bet a friendly machine shop might make you extended caps that are longer than 20mm for not much more than $100...

There's not a lot to them apart from the thread.

[John Kat]

Great info!
I collected the data on the "old" GSXR forks that I'll add tomorrow.
By the way, I noticed that Ohlins now produce RSU upgrade forks for bikes like the FJR 1300.
Surely not cheap but it would turn heads for sure

More suspension tech details....check this chart out.

06 Gixxer 750 forks are 18 mm longer than the 04 GSXR 1000 forks I have now. Unlike the Bandit forks, they're new tech and have compression, rebound, and preload adjustment. The spring rate is correct for GS applications at 1.0 kg/mm.

Also, 20 mm fork extender caps are available for the 750 forks, for a total of about 1.5 inches of additional front ride height over what's on the bike now.

So, it'd bring the fork length to 758 mm.

Stock GS1000 forks are 775 mm for reference, so using the 06 GSXR 750 forks with the extender caps would drop the front end down about 1.6" over stock, factoring in the 17" front GSXR wheel. Not bad.

And they look trick in that nice anodized black.

Interestingly enough the SV650 uses a 4.5x17" rear wheel (160 tire) and those wheels are cheap as chips on eBay right now....a 160 definitely turns in faster than a 180...

Also uses a 20 mm axle so if some 20 mm chain adjuster blocks can be slotted into the GSXR 1000 swingarm, we might have a winner....

Would need some wheel spacers made up but no biggie....

I took no risk by using a complete GSXR 4.5 inch rear wheel on my GS 1100 Kat.with a 530 chain.
The front sprocket needs to be offset by 13 mm.
The AFAM P/N is 25003-16T

Good to know for those using the stock 1100 swingarm.

[John Kat]

I took no risk by using a complete GSXR 4.5 inch rear wheel on my GS 1100 Kat.with a 530 chain.
The front sprocket needs to be offset by 13 mm.
The AFAM P/N is 25003-16T

I checked the alignment with a laser tool.

[Agemax]

the wheel is all gsxr, nothing machined, just bolted straight in.
the swing arm is a one off made by JMC, it is a gsxr arm with a gs1000 pivot so it uses the stock gs spindle.
the JMC arm did come with 2 x5mm spacers that fit either side of the wheel in the swingarm

i have a gsxr1100 rear wheel with a 180 tire, bolted straight into a gsxr1100 swinger with no mods on spacers etc. 530 chain and sprockets and a 1/2 inch offset front sprocket.
admitedly the chain is close to the frame, but it clears it and the 2 sprockets are dead in line

Which sprocket carrier did you use, the GS or GSXR?

Also what is the spindle diameter at the pivot on that GSXR swingarm?

[Agemax]

i have a gsxr1100 rear wheel with a 180 tire, bolted straight into a gsxr1100 swinger with no mods on spacers etc. 530 chain and sprockets and a 1/2 inch offset front sprocket.
admitedly the chain is close to the frame, but it clears it and the 2 sprockets are dead in line

[John Kat]

Thanks!There is maybe another explanation about the difference in road holding between the two versions I built: the fork mounted fairing!
I discovered this on my 100%OEM GS 1000ST that handled very poorly, specially over 100 km/h.
After a lot of trials and errors, I discovered that the fairing had a very negative effect on high speed handling.
This could also explain the difference between my two versions of my GS 1000 XP as I never tried my first version with a fairing!
Later on, I discovered that the fairing was not the root cause of the weave on the std bike but the non-linear response from the suspension
Any small bump would unsettle the bike at speed made all the worse with the fairing...
First I replaced the old Konis that are apparently well know to develop hard spots over time.
The situation improved a lot but I still could not attack the turns with full confidence.
So last but not least, I changed the front fork for a true OEM one and...bingo the issue disappeared totally
The issue was related ( I believe) to stiction in the non-OEM front fork tubes.

Glad to see you are back to the GS R&D
I followed your thread carefully before upgrading my own GS's.
Strangely, I decided to go less agressive than what you did.
First try was with my GS 1000 S that I equipped with GSXR 2nd gen wheels ( 4.5" rear), monoshock swingarm and RSU fork.
My ground clearance was also a little too low ( upfront) for my liking, so I decided to move to GSXR 1st gen components.
The fork is much longer and I have now the 18" wheels.
The roadholding is not quite at the same level as the previous set-up but it could be because the front fork is too softly sprung?
Maybe the tires also allthough I used radials for both?
Here are pictures of the two set-up's

Nice bike! What do you mean when you say the roadholding is not at the same level? From what I've seen, 1 kg/mm springs in the forks are correct for any type of aggressive cornering with GSXR forks on a GS1000.

[John Kat]

Glad to see you are back to the GS R&D
I followed your thread carefully before upgrading my own GS's.
Strangely, I decided to go less agressive than what you did.
First try was with my GS 1000 S that I equipped with GSXR 2nd gen wheels ( 4.5" rear), monoshock swingarm and RSU fork.
My ground clearance was also a little too low ( upfront) for my liking, so I decided to move to GSXR 1st gen components.
The fork is much longer and I have now the 18" wheels.
The roadholding is not quite at the same level as the previous set-up but it could be because the front fork is too softly sprung?
Maybe the tires also allthough I used radials for both?
Here are pictures of the two set-up's

Getting the GS R&D building bug again...

It's getting to be winter project time so I have a few things to do on the bike this winter:

Improve ride height: As cool it looks (IMO), I think the Gixxer 1000 front end will be eventually replaced with something like a Bandit 1200 front end. This will help regain valuable ground clearance. With RSU forks, it will give the bike a more traditional appearance vs. the USD forks it has now. Also, I don't like how the bike looks like it's leaning forward, so longer forks should "level" the appearance of the bike. Hurts the boys too when you're pretty much sitting on the gas tank when hard on the brakes.

Quicken the steering, improve chain straightness: Considering replacing the current 5.5" x 17" rear wheel with a 4.5" x 17" rear wheel, from a Bandit 600 or Katana 600. This help by allowing me to run a 160 vs. 180 rear tire, quickening the steering by narrowing the tire and raising rear ride height by about 12-13 mm, while bringing the rear sprocket closer to the center of the bike, making for better chain alignment. I'd like the bike to be able to turn in faster. As it sits, the front and rear sprockets are probably ~ 10 mm out of alignment, causing premature chain and sprocket wear. I want to get the sprockets dead nuts straight if possible.

GPS speedometer: I like the idea of having a speedometer which is self-contained, doesn't need a reading from a front wheel sensor etc.