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Weekend Wrenching: Installing a Katana Front End

Started by dgyver, November 22, 2004, 11:34:17 AM

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dgyver

Installing a complete 89-97 Katana 600/750 front end

Parts required from an 89-97 Katana 600/750:
- Fork tube assemblies
- Complete triple assembly (upper & lower clamps with stem & bearings)
- Brake rotors (left and right, Katana rotors and smaller in diameter)
- Rotor bolts (5 additional, 10 total required)
- Calipers (left and right)
- Brake Pads (2 sets)
- Brake lines (dual caliper setup)
- Axle (the 98+ Katana axle is the same as the 89-97 Katana, the GS axle is too short)
- Fender (the GS fender may fit)
- Clip-ons (the Katana used clip-ons that mounted to the top of the upper triple clamp)
- Front wheel (same as GS)
- Right side spacer (same as GS)

Parts re-useable from the GS:
- Front axle spacer
- Nut for front axle
- Speedometer pick-up
- Front wheel
- Right side spacer
- Rotor bolts (5)


The steering stem of the Katana is longer than the GS stem but both of the steering stems are the same diameter. There are several ways to solve this problem.

Some GS & Katana stems are welded to the lower clamp while others are pressed in. The pressed in ones can be pressed out of the GS lower triple clamp and pressed into the Katana lower triple clamp.

Another way is to have the stem shortened and re-threaded by a machine shop on a lathe. Not sure if it can done with the stem still installed in the lower clamp. This would be the most costly of options.

The Katana stem can be modified while still in the lower triple clamp. The way I did mine was with a file. I measured the difference in the stems and marked the Katana stem using a pipe cutter. This gave me a perfect line to work with. Not that I could file it perfectly anyway. After about 30 minutes of filing and trial fitting of the upper bearing, the correct height was obtained. I found that 131mm was required between the upper and lower bearing races. Now with the bearing in the correct location a spacer is needed to take up the difference between the upper bearing and the steering head nut.

The steering bearings are the same for the GS and Katana. The lower bearing inner race is pressed on and will be very difficult to remove cleanly from a triple with a welded stem. Also, there is a dust seal on the bottom race that can be easily damaged if the race is pried off. One of the bearings on my Katana triple was bad but I was able to disassemble a bearing from another triple and install it on the project triple. Make sure you lube the bearings while it is apart. I used white lithium grease.


The distance between the upper and lower bearings I found to be 131mm.



Enough material was removed to reveal 28mm from the original machining below the thread to the new shoulder for the upper bearing.



With the bearings installed.



Note the extra length of the stem between the threads and upper bearing that needs to be made up with a spacer.



Here are the bushings that I made to make up the difference in the stem lengths. The left one is made from 1/4" flat bar but has been milled slightly less than the original 1/4" thickness. The one on the right is made from 3/8" aluminum flat bar and has the step in it for the dust cover. PM or email me if you need a set of bushings. I can make a set for a small fee.


Left bushing is for above the stem nut and the right bushing is for below the nut.



Final install of the stem with the bushings.



Installed Katana front end with a pressed in GS stem.



Installed complete Katana front wheel setup.



GS rotor on left and Katana rotor on right. Note that there is a left and right hand rotor for the Katana. The rotors are stamp L and R respectively.



There are several issues that need to be addressed by the bike owner before proceeding with this modification:
1-The GS instrument gauges will not bolt directly to the Katana upper triple clamp.
2-The headlight brackets will not fit on the Katana fork tubes. The fork tubes on the Katana are 41mm where the GS are 37mm.
3-The ignition switch will need to be swapped as well to use the same key.
4-The steering stops will need to checked and modified as needed.
5-The GS handlebars will not work. If you do not get the knuckles for the stock Katana handle bars, clip-ons can be used from other bikes using 41mm tubes (F2, F3, VFR 750/800, VTR 1000, ZX6 D/E (90-03), ZX6R (95-97), Bandit 600, Katana 600/750, RF 600, SV650/s, FZR 600, YZF 600)

Knuckles for Katana clip-ons mounted underneath the triple clamp. They are factory mounted above the clamp.



Additional notes:
1-The stock GS speedometer pick-up can be retained.
2-The plastic hub cover on the left side of the GS wheel is removed to mount the left rotor.
3-The GS master cylinder may work with the dual calipers but you might want to upgrade to a GSXR setup. This would allow for better feel with the dual caliper. Also each of the Katana calipers has dual opposed pistons, 4 pistons per caliper. The GS caliper has only 2 pistons per caliper.


Fork Specs (froma Race Tech's website):
89-97 Katana GSX750 forks are 41mm, made by Showa with a spring rate of 0.629kg/mm
89-97 Katana GSX600 forks are 41mm, made by KYB with a spring rate of ________kg/mm (still need to confirm the spring rate)
88-90 GS500 forks are 37mm, made by KYB with a spring rate of 0.445kg/mm
91-03 GS500 forks are 37mm, made by KYB with a spring rate of 0.594kg/mm

I have been told recently by a Katana wrencher who said that he has not seen any differences in the internals between the 600 & 750 forks. I have yet to confirm this.

Not sure about the fitment of the 98+ Katana front end. The front wheel uses different length spacers but the axle length and diameter are the same. Calipers, rotors, and fender are different as well.

I have tried to address all of the issues that I know of. This has been done on a race bike so there is not any of the street gear to deal with.
Common sense in not very common.

Kerry

I copied the photos to my webspace, renumbered the filenames to be in "post order", fixed the URLs and removed the move / rehost request at the end of the original post.

Keep it up, dgyver!  :thumb:
Yellow 1999 GS500E
Kerry's Suzuki GS500 Page

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