Author Topic: K100 GSXR conversion questions  (Read 922 times)

Offline Max

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Re: K100 GSXR conversion questions
« Reply #25 on: September 24, 2018, 11:22:46 AM »
Nickheijman 👍Cheers bud. I am still going ahead with the GSXR front as I have come this far. Be careful with what brakes you put on as I have looked into upgrading my master cylinder to a k1100 as the diameter is 20mm but this then means I have to change the controls, throttle etc and this is not cheap. What I am going to do is use the gsxr600 twin pot calipers as this will work fine with the standard 13mm set up on the BMW.

Google is your friend if you like computers and the Internet. I don't! Infact I hate computers because I cannot see how they work. Trial and error and having the balls to give things a go is what I find works but thank you for all the constructive comments. The thing that got me was being told the GSXR wheel cannot take the tire but without any explanation why?

The pic is the Firestone classics I want to buy in a 17" tire. I'm sure they will work but only way to know is to try. If not I have other bikes I can put them on, it's only money.
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Offline NickHeijman

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Re: K100 GSXR conversion questions
« Reply #26 on: September 24, 2018, 11:47:04 AM »
The tire looks good !

Iím planning to change the controls also, so I will buy a brembo master and clutch set this winter when I do the USD fork swap.
Regarding the K1100 brake cylinder, iím using one now on my k75 and it works like a charm bro!
Here is a picture.

I used the throttle cable of the k1100 with a custom braket on the k75 throttle body.
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #27 on: September 24, 2018, 02:11:24 PM »
I'm struggling to find a k1100 set up second hand and its around $500 new, might be cheaper to buy a k1100 complete. Love the intake on the k75 bud, bet she sucks like a prostitute.
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Online Laitch

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Re: K100 GSXR conversion questions
« Reply #28 on: September 24, 2018, 02:19:39 PM »
Love the intake on the k75 bud, bet she sucks like a prostitute.
Don't try that with it at home, Max.  :nono
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Offline NickHeijman

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Re: K100 GSXR conversion questions
« Reply #29 on: September 24, 2018, 02:57:24 PM »
For me the k1100 is just temporary since I borrowed it from a friend. The female banjo is thread is worn out on my k75 master cylinder. As mentioned I will go for a brembo set with also a usd swap so for now its okay. For you it will be a good solution to use the 4 pod calipers with the usd form and oem handlebar controls. How come they are so expensive if you want we have these k1100 local for not more then 100Ä used in good shape.
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Offline johnny

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Re: K100 GSXR conversion questions
« Reply #30 on: September 24, 2018, 03:54:52 PM »
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Offline robotradio

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Re: K100 GSXR conversion questions
« Reply #31 on: September 26, 2018, 12:29:13 PM »
I'm doing a GSXR conversion myself on a '91 K100 LT.  Purchased donor fork from 2008 GSXR 600, cognito moto conversion stem and cognito moto gsxr machined upper triple, allballs bearings same for top and bottom (99-3521-5) , front brake calipers from 2009 Yamaha R6r paired with venhill brake lines, mswitch 3 button control / munit blue / master brake cylinder / clutch controls from amazon.  I will be reusing the bmw rim on the gsxr front with some tbd spacers. Ditched the choke.

https://www.allballsracing.com/99-3521-5.html

https://cognitomoto.com/collections/fork-conversion-parts/products/gsx-r-fork-on-bmw-r50-r60-r75-r90-frame-conversion-stem?variant=3724295241768
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Offline robotradio

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Re: K100 GSXR conversion questions
« Reply #32 on: September 26, 2018, 12:31:16 PM »
What's keeping you from using the BMW rim? Aesthetic?
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #33 on: September 26, 2018, 01:22:54 PM »
Fair point! I thought trying to make to BMW wheel fit would be a nightmare in itself, as in disk alignment to the calipers, disk size etc. I am going to play around and see if I can make it work. Where do these spacers go? Between the disk and wheel or disk and fork?. I have a complete GSXR front end and just tried like for like but you have got me thinking now.
I have ordered the cognito stem and top yoke, just waiting on delivery to continue
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #34 on: September 28, 2018, 01:26:06 PM »
Ok so I have the original BMW wheel fitted to the GSXR forks with spacers and now have an issue with caliper alignment as the BMW disks are too small a diameter. I have 1998 GSXR forks with 90mm hole centres for the caliper mounts, r6 calipers have 100mm mounting points so they won't work. Either I find larger disks to fit the BMW wheel or find calipers with 90mm mounting points that sit at an angle to fit the BMW disks.
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Offline NickHeijman

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Re: K100 GSXR conversion questions
« Reply #35 on: September 28, 2018, 01:34:51 PM »
What about the GSXR calipers? Will they do the job?
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #36 on: September 28, 2018, 01:40:05 PM »
Got them on at the mo, the GSXR disks are a larger diameter than the BMW disks so the brake pads are only just on the outer edge of the BMW disks. I have a set of BMW rr wheels that would work but I don't like the off set on the rear wheel as its about an inch off centre and looks pants.
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #37 on: September 28, 2018, 01:44:09 PM »
Next challenge
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #38 on: September 28, 2018, 02:14:51 PM »
I have also solved the issue regarding the GSXR wheel with a cafe style tire on. I spoke to a TT racer and he explained the difference in radial and crosply tires and said I could put a crosply onto the GSXR rim with the use of an inner tube but this would make the front end twitchy and dangerous. I can use a radial on the rear BMW rim no problem but this is not the look I am going for, So once again it's back to the drawing board.
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Offline NickHeijman

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Re: K100 GSXR conversion questions
« Reply #39 on: September 28, 2018, 03:58:00 PM »
Ah okay I see you need bigger rotors, however it must work because a lot of people did it before :)
I'm going for the ZX9R or ZX7R fork, this is interchangeable and also the BWM K rims will go in easy with the stock Nissin callipers.

Good luck, looking forward on your end result.
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #40 on: October 11, 2018, 12:57:37 PM »
Ok so I have decided to carry this on for future Frankenstein minded people. The cognito moto trees are fitted, I'm not overly impressed with the trees as for a polished finish they are covered in machining marks and has a score running across the top tree. I will have to anodise or paint these now, also the steering stops are rubbish and I had to grind down on the inner lip to clear the steering tunnel, even with spacers on the stem, then add a 4mm rubber pad as there was not enough adjustment on the stops.
The tire issue has been solved by running a 110/70/17 on the GSXR rim and a 140/60/17 on the k1100 rim. I know I could have gone to a 160 on the rear but you will gain much more in height than you would width because of the narrow rim and this would change the geometry even more. In reality the bike has been lowered a total of 46.6 mm front and back with the the aid of the adjustable rear shock, not ideal but best I can get it, the test will be in the ride. I am interested to see how this effects the side stand issue too, should help if any thing and better than attaching a big block on the end of it.

I have also upgraded the rear disk and pads to brembo as the front now has 6 pots. Side exit exhaust fitted and just the electrics and hook up the koso dl-03sr speedo to work out.
NickHeljman thanks for the offer on mastercylinder bro but I'm going to buy the k1100rs master new, I have gone this far with it and can't cheap out now.
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Offline robotradio

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Re: K100 GSXR conversion questions
« Reply #41 on: October 12, 2018, 06:43:44 PM »
Thanks for the update! I went with the black anodized gsxr -> bmw conversion top triple.  I also noticed the machine marks, but gives it more character :P  So your analysis is that the bmw brake rotors won't fit with the gsxr calipers? I personally have 2006-7 GSXR 600 front end, so the sizings are probably a little diff than your 98(?) gsxr front. 
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Offline Max

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Re: K100 GSXR conversion questions
« Reply #42 on: October 13, 2018, 04:37:02 AM »
It was not the machining marks that bothered me so much as the score down the middle of the top tree, this is a machining line where the two surfaces are slightly different heights.
Regarding the rotors I worked out if I used a k1100 rs front wheel as the spindle size is the same, rotor dimensions are 300mm then did some reading into what Suzuki runs a 300mm rotor. The closest I could find was a 305 rotor on a Suzuki ( can't remember which ) this would mean there would be a difference in cercumfrance of 2.5 mm and would mean I would have to purchase another set of calipers, as well as the k1100 wheel and disks. You just need to look to find what will work for your set up and then get a master cylinder to fit, but then in changing the mastercylinder you also will need to change the controls,throttle etc.
What I am looking into now is a BMW r1100s front wheel, the spindle size is smaller but wonder if I can press bigger I/d bearings into it to fit the larger spindle. Disk rotors are the same 320mm as the Suzuki so it should work.
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