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Wheel Swaps


  • Wheel Swaps

    Wheel Swaps

    *Originally posted in the Wiki by user Wild-Bill. Edits for viewability or broken links with source change have been made*

    1100 Wheel Swap

    I upgraded from a ’95 750 to a ’92 1100 Kat last fall. The bike came with a number of extra goodies including a 17x5.5” rear wheel from a ‘91 GSXR-750. Having read a lot about the stability benefits as well as the better availability of 17” tires versus 16” I decided to use the winter to do the conversion. Things drug into the spring but that’s mostly due to work and the family life getting in the way of quality time with the bike.

    Note: This information is duplicated from my worklog thread:

    I've got a pretty well-equipped garage with a drill press, wood lathe, wire-feed welder, Dremel and an angle grinder. What I don’t have available is a metal lathe or mill and the biggest drill bit I have on hand is ½”. This imposed some restrictions. I can’t fab up much in the way of custom length spacers, a new axle or bushings to adapt a different axle to my forks or swingarm. With these restrictions in mind, I wanted to keep the custom fab work to a minimum although some was required. Besides that, I wanted to keep costs down to a minimum. This wasn’t going to be a no-holds-barred, spare-no-expense kind of project; more of a watch-the-budget, match parts as much as possible, mod only what needs it kind of thing. Rear Wheel:

    Edit: I'm leaving this in because it was my first impression and, who knows, maybe someone will be dead-set on a 5.5" rim. Following some riding, I discovered that the 180/55-17 tire was rubbing on the chain. Adjustments didn't do much good and neither did adding some washers behind the sprocket. It all looked fine sitting on the centerstand but when I was rolling, either the tire rubbed the chain or the swingarm on the other side. After considerable messing around I finally replaced the GSXR wheel with one from a '96 RF600R, fitted with a 160/60-17 tire. That went in just fine with plenty of clearance. I know the tire is only 10mm wider than stock but modern radial tires handle and grip so much better than bias-ply that it still makes a big difference and moving the rotating mass out 1/2" is good for the handling, too. The GSXR rotor bolted right up to the RF600R rim but I needed a RF600R hub and cush drive rubbers because it uses a 5-point hub versus the GSXR and Kat 1100's 6-point hub. I also had to use a 5-bolt sprocket. The one I used fits an RF600R, Kat 600/750 and a whole bunch of other bikes. I swapped out the chain and front sprocket at the same time since I had the parts on-hand. For spacers, counting from the left, I used a 13/16" hardened washer, the Kat 1100 spacer, the RF600R rim, Kat 1100 spacer (with the tin collar removed), Kat 750 caliper arm (drilled out to 13/16") and the custom spacer detailed below. Everything bolted right up with no problems.

    When I bought my 1100 it came with a rear wheel from a ’91 GSXR-750 in the box o’ spare parts. The rear wheel came with a 180/55/17 tire already mounted, a sprocket carrier, and bearings already installed but no brake rotor. A quick look at the wheels next to each other showed some differences. The Kat rotor wouldn’t bolt up to the GSXR wheel because the Kat uses 6 bolts and the GSXR uses 5. The GSXR hub width is narrower than the Kat’s and, of course, the rim width is significantly wider but they both came fitted for a 20mm axle. I threw the GSXR wheel on the Kat for an initial look and turns out the 180/55 tire fit in the swingarm just fine but I was definitely going to have to play with spacers to get everything lined up right.

    The Kat sprocket carrier fits into the GSXR cush drive perfectly so using it and the stock left-side spacer puts the sprocket in exactly the same position, side-to-side as with the stock wheel, lining up the front and rear sprockets very nicely. Winner! Now for centering the wheel… Once I got the wheel straight, the rim lips lined up about 2.5mm to the left of center. Not perfect but it should be OK. If it really bothered me I’d grind down the left spacer (or, now that I know it works well, weld up a new spacer using 13/16” washers and add washers between the sprocket and the carrier to keep the sprocket lined up right). With the GSXR wheel’s narrower hub there was considerable space left on the right side of the axle so lots of room to play with there but what about the caliper mount?

    Some searching on MetalGear’s website ( showed that the ’89-’91 GSXR-750 had a 240mm OD rotor. The 1100 had a 275mm rotor which is way off but the pre-750 had a 250mm OD rotor. That’s close enough and pre-Kat parts are cheap so that made using a Pre-750 caliper and mount a good option. Added bonus is that the 750 Kat calipers are mounted above the swingarm, like the 1100’s so I could use the stock caliper arm mounting point on the swingarm. No messing around with clearing the centerstand or using the centerstand bracket. I like that. So I sourced a GSXR rotor, a pre-750 Kat caliper and a matching bracket from E-Bay, had the axle hole drilled out to 13/16” (at the base Special-Purpose Vehicle Maintenance shop—thanks, guys!) and I was in business.

    I mounted the wheel with the OEM rotor, stock Kat left and right spacers and the newly drilled-out 750 caliper bracket. That left me with about 10mm empty space on the right side of the axle. I filled this with 13/16” washers from Ace Hardware. Turns out there’s room for about 2 ½ washers. Hmm… That’s a long way to flex the swingarm. Added to that, when I bolted up the caliper and centered it on the rotor I needed about 2 ½ washers to the inside of the bracket and 1 on the outside of it. Solution: I put 1 washer on the outside, 2 washers on the inside, filled the gap between the 2 washers by wedging in a couple thin washers and spot-welded over the gaps with a wire-feed to hold them lined up right. Pull everything back apart, weld the rest of the way around the washers, hit it with the angle grinder to make everything pretty and voila! I’ve got a custom spacer. I ended up just a little too thick and it’s a pain cramming all those parts in there one at a time so the answer is to use a slightly thinner ¾”washer. I mounted that up in my wood lathe and used the Dremel to grind the hole out to a hair over 20mm. If I didn’t have the wood lathe I could have done it freehand with the Dremel but it wouldn’t have been as neat or as convenient.

    Next was the caliper arm. (The bit that goes from the caliper, forward to the swingarm to keep the caliper bracket from rotating on the axle.) The OEM arm doesn’t quite line up with the 750 caliper and the U-fitting at the end of the arm isn’t wide enough to go around the lug on the caliper.

    Wire-feed to the rescue! I picked up a chunk of 1” bar stock and some ¾” square tubing, then bent and drilled new U-fittings. (Note: the fitting at the swingarm end has two different size holes. Drill the smaller one first and then expand the inside hole. You want these holes to line up.) I loosely bolted up the new U-fittings with the wheel and caliper in place. (Caliper at the 12 o-clock position on the wheel.) I measured, cut and tack-welded the square tubing to fit and then pulled the assembly off the bike to finish the welding at the bench. I bent some coat hanger to make the hose holder and welded that at the same distance from the caliper as the OEM arm. A little paint and she was beautiful!

    That about did it for the rear wheel, mechanically. Next it was new bearings, a tire and we’re done. Since the 750 caliper I bought for the project still looked good (black anodized) I left it alone with the exception of a quick re-build.

    Front Wheel:

    The stock front wheel is 2.75” wide with a 17mm axle. Just about any 17” wheel would be an improvement over that since they seem to start at 3” and go wider from there but there aren’t too many 17mm front axles out there. I’m a little picky in that I wanted the front wheel to match the spoke style on the rear wheel. That limits the wheel choice a bit. Based on jaluesing’s wheel conversion write-up ( I got the idea that a pre-600/750 wheel would fit—and it would if I wanted to use the 600/750 15mm axle.

    If I wanted to use that axle, I’d need a metal lathe (which I don’t have) to turn adapter bushings for where the axle goes through the forks and I’d have to get some 15mm spacers to center the wheel up. Oh, and I’d have to get a speedo drive and an axle or turn a custom axle on that lathe I still don’t have. That’s a lot of pain. I’d rather use my original speedo drive and axle and get bearings to adapt the wheel. Unfortunately, it turns out that the 17x42x14mm bearings I’d need to put that wheel on the 1100’s 17mm axle aren’t readily available except as the left wheel bearing for an 1100 Kat at $30 each from the dealer. Good grief! That’d be the cheapest short-term solution but any savings would evaporate the first time I needed to replace bearings. Back to the drawing board.

    Other options were wheels from a 94-96 RF-600R or an early ‘90s GSXR. As I mentioned earlier, I wanted to stick with the slanted spokes to match the rear wheel. Also, there have been some reports of problems fitting opposed-piston calipers on wheels with straight spokes. Apparently the straight spokes tend to be thicker than the slanted ones and hit the calipers.

    I found a wheel from a ‘93 GSXR-750 locally on CraigsList for $100, rotors and calipers included but that guy flaked out. Back to the internet… Finally, I found one for a good price on E-bay but without rotors or calipers. On a ’93 GSXR there’s a 20mm axle and the bearings are listed on Ron Ayers’ website as 20x47x14. The bearings to adapt that to my 17mm axle are 17x47x14. Now, that’s a common size! There’s a write-up from garyphiliph describing his experiences adapting Nissin 4-pot calipers to fit his forks after mounting that same wheel. Apparently the rotors are 6mm closer to center than the 1100 Kat rotors so I can expect to have to fab an adapter plate. That, I could do. Since I didn’t buy the complete setup from the Craigslist seller I didn’t have Nissin calipers or GSXR rotors, though. Turns out the rotors I had left over from the 600 Kat rim bolted up fine. The diameter is a bit different from the GSXR ones and the offset is also a bit larger. (Kat rotors: 290mm OD, 19.5mm offset. GSXR rotors: 310mm OD, 22mm offset.) I was going to have to build adapter plates for the GSXR calipers anyway so I figured I’d give it a go!

    The GSXR wheel, as mentioned, originally rode on a 20mm axle. That means it has a 20mm ID hub spacer. With the new 17mm ID bearings that’s going to be a little sloppy, possibly not fully backing the bearings’ inner races. Answer is to replace the spacer with a 17mm ID one. That’ll keep it centered on the axle and fully supporting the inner bearing races. Let’s see, what has a 17mm axle? Hey, the rear axle of a pre-600/750 is 17mm! KR to the rescue! I put out a call for help and had several KR members offer to mail me a rear wheel hub spacer. I cut that down to the 174mm length of the GSXR hub spacer using the angle grinder with the spacer mounted in the wood lathe to make sure I was cutting it straight across. The GSXR hub is actually a little narrower than the 1100 Kat hub so with all the original spacers I needed one 5/8” washer modded to fit on the 17mm axle to make everything fit in the forks beautifully.

    The next challenge was the speedo drive. Turns out that, just like KFreak warned me, the 1100 Kat’s speedo drive almost, but not-quite engages the drive tabs on the GSXR wheel. The calipers show that the OD of the tabs on the speedo drive is exactly the ID of the tabs on the wheel! If I went with a GSXR speedo drive it would match up right with the wheel but the 20mm ID (to match the GSXR axle) would leave it sloppy on my 17mm axle and might not match up right to the bearing’s inner race. I looked at the clearances and decided the best bet was to make an adapter to fit my 1100 Kat speedo drive to the GSXR wheel. I used 1/8” thick aluminum plate from an old street sign (The world’s best bracket material!) and cut it out with a scroll saw.

    The first attempt ended up fitting in the wheel perfectly although, looking at it, I should have pre-drilled all the inside corners and beveled out the inside tabs. I’ve made those changes in the drawing. I did the drawing with IMSI TurboCad 2D, a free basic drafting program. If you’d like a copy of the .tcw file let me know and I’d be glad to send it to you via e-mail.

    The caliper adapter brackets were next. The critical dimensions are the hole spacing and the thickness at the point where the calipers attach. I mocked up the adapters out of some plastic sheet I had lying around and used washers to get the thickness right. I cut the adapter plate out of some heavy-duty angle iron, welded nuts at the fork mounting points and spacer plates to the caliper mounting points of the bracket. No big deal, right? I would suggest drilling the holes a little oversized. If you try to get things too tight then if your hole centers are just a little off then things won’t line up at all.


    The GSXR wheels both came with ratty looking black spray paint finishes. That wouldn’t do. No point in going to all this work and ending up with something crummy looking. My old Kat 750 came with bare aluminum rims and I always liked that look so I decided to go with that. Turns out that the wheels came from Suzuki with a pebbled finish on the spokes/hub and a smooth surface on the outer rims. The combination of that pebbled finish and what has to be the world’s greatest primer makes it really hard to get all the paint off. I tried with the rear wheel and gave up. New plan: Paint the hub and spokes silver and just clear-coat the rim. The front calipers came with gold paint (tacky!) under a whole bunch of grime. They got gloss black paint to clean up the look.


    Tire size discussion:

    Since the whole point of this business is to get better stability in turns and get a better selection of tires, I didn’t want to mess much with the bike’s geometry. This means I wanted to end up with the same diameter tires as stock or at least as close as I could get. That way I get the advantages of moving the rotating mass out from the axle without screwing up the rake/trail or vertical center of balance. Being an avid Excel junkie, I figured I could make the computer do the drudgery of bashing numbers around. I found the formula Diameter in Inches = Rim Diam Inches + [ (2 x Aspect Ratio x Section Width) / 25.4] on , plugged it into Excel and divided the diameter by 2 to get the radius. (Center of the axle, measured from the ground.) I started with the stock tires on the 16” rims (120/80/16 and 150/80/16) and then compared those numbers to some likely-looking 17” tires. Turns out a 120/70/17 front tire and a 180/55/17 leaves the front axle at the stock height and lowers the rear end by .3”. I’d say that’s pretty close and those tire sizes are readily available. Wrap-Up:

    When I started this I had no idea how involved it would get. I also had no idea how many family issues would get in the way of some quality time in the garage. I’m glad I did it, though.

    By the time I finished building the adapters and test-fitting everything, it all bolted together really easily. The 185/55 rear tire was a pretty tight fit in the swingarm and I had to remove the chain guard to get it in there but once the wheel was in place the chain guard fit back in there just fine. The only problem was working around the stock exhaust. A 175/60 tire might have been a better choice for fitment issues. I may try that next tire change although the Pilot Power 2CT tires don’t seem to be available in that size. Then again, one of the reasons for going through all this was to get a better tire selection, right?

    The bike feels a lot lighter with the larger wheels. I noticed the difference just rolling it out of the garage. For the initial testing I took it to a parking lot and played around doing MSF type maneuvers. Again, in low-speed maneuvering it felt like a lighter bike. Kinda like a long, low-slung 750 Kat. Even with brand new tires I was quickly feeling perfectly comfortable doing 20 foot diameter donuts and figure-8s. Some of this may have just been due to tires that weren’t flat in the middle but it felt like a whole new bike.

    I’m still having issues with the brakes. The front brakes feel like they still have some air in them even after pumping most of a whole bottle of Dot-4 through them. The rear brake feels fine except that I have to move the pedal a lot farther than I did with the original brakes. The answer may have to be swapping the master cylinders. We’ll see. I’ve been planning on replacing the lines with braided ones anyway so maybe that’s as good a time as any to play with MCs.

    Edit: The issues with the front brakes ended up being caused by worn caliper pins. The pads were catching on the pins and then flexing as I squeezed the lever harder. It felt for all the world like air in the lines and I spent an incredible amount of time andd effort bleeding the brakes before I realized what was going on. Lesson learned; if you're going to rebuild calipers, spend the extra couple of buck for some new pins.

    This information was last originally posted on 8 February 2012 by User Wild-Bill in the old Wiki.
    Last edited by Kreylyn; 06-23-2019, 10:16 AM. Reason: Updates

    • Kreylyn
      Kreylyn commented
      Editing a comment
      Currently only 1 example of wheel swap, for 1100. Plans are to have more options, or articles on wheel swaps for multiple models, and directions to go in. More info needed. Lots of updates needed.
    Posting comments is disabled.





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