Late model GSXR USD Forks w/ Radial brakes on a GS1000SZ Katana??

[fastkatanaboy]

Does anyone know how difficult it is to put Late model GSXR USD Forks w/ Radial brakes on a GS1000SZ Katana??

I noticed from looking at part numbers and diagrams of both that the bearings are different. Could I just swap bearings? I am also wondering about steer stem, length diameter.
What are the steps?

Thanks!

 

[80GS1000]

I put a 2004 GSXR 1000 front end on my 80 GS1000E. It wasn't too hard. I'm in the middle of 2006 GSXR 1000 monoshock conversion as well. Steps are outlined in this thread.

It requires a bearing swap. The stems are the same length, and the Gixxer stem diameter fits the GS headstock just fine.

You will need to lift your back end to keep the exhaust from dragging - either longer shocks or a monoshock conversion. After lifting the back end, you'll need to check your steering geometry to make sure you're in the sweet spot for handling. Too little trail and your bike corners at low speed unbelievably well, but is a wobbly deathtrap at high speed, too much and it'll track in a straight line great but corner like a Winnebago with two flat tires. In the sweet spot, it'll corner well and track in a straight line well too.

 

[Guest]

with the late model conversion you will lose your speedo drive and have to go electronic. I believe the radial forks are only 28.5". stock is 32 and you will lose another inch going to the 17" wheel. The big danger is right hand corners if you have a header. if you hit any bumps while in the corner you will bottom out......which is not good. If its for a drag bike ok.or if your header is in the center of the bike and not off to the side like a vance and hines.

I have been kicking the idea around myself of going to radial front end but with my 29.5 inch gixxer forks plus another inch of height from my drop triple I still bottom out once and didn't like it one bit. I don't know if I want to lose 2 more inches.

the shorter forks drops the trail considerably and quickens up the steering. I don't know that jacking the backend up is such a good idea and it only marginally gains you height at the front of the engine.

Just one mans oppinion

 

[80GS1000]

with the late model conversion you will lose your speedo drive and have to go electronic. I believe the radial forks are only 28.5". stock is 32 and you will lose another inch going to the 17" wheel. The big danger is right hand corners if you have a header. if you hit any bumps while in the corner you will bottom out......which is not good. If its for a drag bike ok.or if your header is in the center of the bike and not off to the side like a vance and hines.

I have been kicking the idea around myself of going to radial front end but with my 29.5 inch gixxer forks plus another inch of height from my drop triple I still bottom out once and didn't like it one bit. I don't know if I want to lose 2 more inches.

the shorter forks drops the trail considerably and quickens up the steering. I don't know that jacking the backend up is such a good idea and it only marginally gains you height at the front of the engine.

Just one mans oppinion

True about the losing the speedo. You'll have to (twist your arm) go to an electronic speedometer. Looks trick on a 20+ year old bike.

Ground clearance under the lowest part of the frame in that photo above is sitting at 8.5". With the V&H 4 into 1 header mounted, it sits at about 4-4.5" of clearance between hard parts and the ground (I need to get the bike off the jack and remeasure again), which is plenty considering the late model suspension's and radial tires' superior ability to soak up bumps. Trail is sitting at 3.6", which is in the sweet spot between quick steering and stability.

Not trying to be argumentative, just saying that using late model Gixxer forks can be safely done with some planning and careful engineering. Not sure if you can do it though with the stock swingarm (or even a GS1100 swingarm) though, a monoshock conversion may be required to get all the variables right since it makes it easier to configure the steering geometry into the correct values since it lets you raise and drop the bike as needed. When I put the new forks on the bike, it sat MUCH too low with the stock swingarm and shocks. The header was hovering about 2.5" from the ground.

YoshiJohnny did the pretty much identical swap with great results. He reports never having ground out his header in the bumps or in the corners, and he has no chicken strips on that 190 radial in the back.

Easiest GSXR fork swap (so I hear) is a 89-95 GSXR 1100 front end. The bearings on those front ends bolt right up to the GS frame, and they're much longer than the late model GSXR forks.

 

[Guest]

My comments were cautionary only. My forks on my kat are 2" longer than yours and I have had an issue in one corner. They are ohlins sprung and valved so they work well.
I love the look of your bike and thought about r1 forks for mine as I like the black tubes and calipers. I may have to revisit my oppinion based on your numbers. you have the same clearance I do but with 2" shorter forks? does that include the sag and rider? My Prob was diving hard into a downward/upward corner and touched the right down pipe of the header. I want to sell my pro-lights set up and get a radial setup but......I will go over it again. How much clearance do you have between your chain and pivot? I run a bandit arm and couldn't lift the back end very much or my chain drags across the pivot. I would amagine the same problem exixts with the new gixxer arm as they have a wider pivot than the bandit I think.
Good luck with the project...looks killer. Oh yeh. What are you using for speedo setup?

 

[80GS1000]

My comments were cautionary only. My forks on my kat are 2" longer than yours and I have had an issue in one corner. They are ohlins sprung and valved so they work well.
I love the look of your bike and thought about r1 forks for mine as I like the black tubes and calipers. I may have to revisit my oppinion based on your numbers. you have the same clearance I do but with 2" shorter forks? does that include the sag and rider? My Prob was diving hard into a downward/upward corner and touched the right down pipe of the header. I want to sell my pro-lights set up and get a radial setup but......I will go over it again. How much clearance do you have between your chain and pivot? I run a bandit arm and couldn't lift the back end very much or my chain drags across the pivot. I would amagine the same problem exixts with the new gixxer arm as they have a wider pivot than the bandit I think.
Good luck with the project...looks killer. Oh yeh. What are you using for speedo setup?

Chain/pivot clearance is unknown at this point until the Gixxer 1000 rear wheel, 5/8" offset 530 front sprocket, and 530 X-ring chain arrive, but initial testing with a piece of string on the front sprocket and the Katana 600 rear wheel/530 rear sprocket is promising. I'll post a note about it in my "GS1000 streetfighter idea w/picture" thread when I find out for sure. Sag caused by rider weight and the weight of the bike is an unknown variable right now - I'll check that too with 4 fifty pound bags of concrete mix on the seat to simulate rider weight when the rear wheel arrives and when the needed monoshock mounting adapter parts are made with a special rig I'm planning to make to hold up the rear end of the bike by its new monoshock rear suspension at the proposed mounting location.

The really nice thing about the monoshock conversion is that it makes the bike basically hinged in the middle, so that the distance between swingarm to upper twinshock mounting points is no longer a limiting factor. You can move the bike up and down as required to get all the variables correct.

Speedo setup will be a hybrid between the stock GS1000 cluster with the speedo replaced with a unit from Acewell.

 

[Guest]

Well, kudo's for taking on such an intensive project...I LIKE THAT. I agree the mono is nice for adjusting height.

I will look forward to your future posts and the finished bike. It will look killer no doubt.