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Thread: Front forks 92 R100RS improvements

  1. #1
    Registered User JGREGOR1.JG's Avatar
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    Front forks 92 R100RS improvements

    Guys
    I have a 92 R100RS. One of the pinch bolts has a broken casting. Some PO had through bolted it with a nut and bolt. Seems fine. But the guy I got the bike from had got a set of complete used fork legs. I am thinking of installing better springs in the spare set and what ever other improvements there are to make and swapping them out. The old existing forks on the bike have fresh seals and fresh oil. They are VERY compliant but a bit squishy for my taste. Seems like too much sag as well, using up too much travel though I have never bottomed.
    Anyway, thinking of souping up the spare set. Any suggestions? I guess I could go the normal route and drop proggessive suspension springs in but maybe that's not the best thing?
    I have a billet top clamp coming next week. I know I have to set the sag on the bike.
    Also I have the slightes bit of clicking when I hit bumps particularly when cornering. Put's me off a bit.
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

  2. #2
    . AntonLargiader's Avatar
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    There's a thread from about a year ago about using Gold Valves in these forks.
    Anton Largiader 72724
    largiader.com bmwra.org

  3. #3
    Registered User JGREGOR1.JG's Avatar
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    Quote Originally Posted by AntonLargiader View Post
    There's a thread from about a year ago about using Gold Valves in these forks.
    I was thinking about gold valves and works springs but the amount of set up for me is daunting as I havent much time to play with things. I think I will just set the spares up stock and do a swap. MAYBE progressive suspension springs. Running 7.5 weight BMW fork oil now. Really is not bad. Lot's of dive though. I imagine Progressive's springs may help that but at the cost of a firmer ride.
    Thanks for the response Anton.
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

  4. #4
    Registered User 88bmwjeff's Avatar
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    Quote Originally Posted by JGREGOR1.JG View Post
    MAYBE progressive suspension springs. Running 7.5 weight BMW fork oil now. Really is not bad. Lot's of dive though. I imagine Progressive's springs may help that but at the cost of a firmer ride. Thanks for the response Anton.
    I have Progressive springs in my 88 R100 RT, and I'm running 10 wt oik on the forks to avoid lots of dive. The RS fairing weighs less so perhaps a lighter oil would be appropriate. This is my experience. Keep in mind I'm very much a novice in the areas of forks.
    Last edited by 88bmwjeff; 11-20-2013 at 02:54 AM.
    Jeff in W.C.
    1988 R100 RT (the other woman)
    "I got my motorcycle jacket but I'm walking all the time." Joe Strummer

  5. #5
    . AntonLargiader's Avatar
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    Actually I misread the title thinking it was an R100GS, not RS. The thread I was thinking about was for a GS.
    Anton Largiader 72724
    largiader.com bmwra.org

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    Registered User JGREGOR1.JG's Avatar
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    Quote Originally Posted by AntonLargiader View Post
    Actually I misread the title thinking it was an R100GS, not RS. The thread I was thinking about was for a GS.
    And I misread the bottle of oil the po sent with the bike. It's the BMW 10 wt oil. Naturally 36 dollars a quart as opposed to 10.00 for 7.5 wt.
    I believe I will switch brands!
    I have 10 wt bel ray on hand.
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

  7. #7
    Registered User JGREGOR1.JG's Avatar
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    Quote Originally Posted by 88bmwjeff View Post
    I have Progressive springs in my 88 R100 RT, and I'm running 10 wt oik on the forks to avoid lots of dive. The RS fairing weighs less so perhaps a lighter oil would be appropriate. This is my experience. Keep in mind I'm very much a novice in the areas of forks.
    What brand oil are you using?
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

  8. #8
    Registered User 88bmwjeff's Avatar
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    I've used both Bel Ray and BMW, but mostly Bel Ray
    Jeff in W.C.
    1988 R100 RT (the other woman)
    "I got my motorcycle jacket but I'm walking all the time." Joe Strummer

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    Registered User JGREGOR1.JG's Avatar
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    Quote Originally Posted by 88bmwjeff View Post
    I've used both Bel Ray and BMW, but mostly Bel Ray
    I'll probably go with bel ray 10 and stock springs. Might add a touch of preload though.
    Thanks!
    Last edited by JGREGOR1.JG; 11-20-2013 at 08:37 PM.
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

  10. #10
    MonoRT MonoRT's Avatar
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    If you don't mind spending a bit more, you can send both forks, top cap and all (and a pair of new seals) to Race Tech and they'll choose the spring and Gold Valve settings for you, install everything including oil and send it back.

    I live about 30 minutes from Race Tech, so I drove over there, answered all of the questions about the bike, riding style, passenger (or not) and luggage and just left the forks with them. I have forks where the slider is made by Brembo - I think that your bike would have Showa sliders - at any rate, Race Tech needed to do a little machine work on the lower legs and I don't know if that would be needed with the Showa forks. I picked up the assembled forks and put them back on the bike as-delivered and they've been great.

    I bought my R80RT new in 85 and the fork dive plus the lightly damped pogo effect scared the heck out of me. I tried some heavier, adjustable rate springs from Works, and along with heavier weight oil, I was able to improve the dive situation, but that did not help too much with the pogo stick damping. Varying the oil weight allowed me to choose between a lively pogo stick or a stiff one, but I was never very happy with the fork's ability to track over bumps and dips. Getting onto the Bot's Dots and reflectors between lanes on the freeway would cause the bike's front end to jump all over the place.

    About 15 years ago, I gave up and took the forks to Race Tech. I sure wish I'd done that earlier. It would be a stupid thing to do, but I could ride a line of Bot's Dots all day if I wished - the fork just tracks right over stuff like that. Plus, the dive situation is much better than stock.

  11. #11
    Registered User JGREGOR1.JG's Avatar
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    Quote Originally Posted by MonoRT View Post
    If you don't mind spending a bit more, you can send both forks, top cap and all (and a pair of new seals) to Race Tech and they'll choose the spring and Gold Valve settings for you, install everything including oil and send it back.

    I live about 30 minutes from Race Tech, so I drove over there, answered all of the questions about the bike, riding style, passenger (or not) and luggage and just left the forks with them. I have forks where the slider is made by Brembo - I think that your bike would have Showa sliders - at any rate, Race Tech needed to do a little machine work on the lower legs and I don't know if that would be needed with the Showa forks. I picked up the assembled forks and put them back on the bike as-delivered and they've been great.

    I bought my R80RT new in 85 and the fork dive plus the lightly damped pogo effect scared the heck out of me. I tried some heavier, adjustable rate springs from Works, and along with heavier weight oil, I was able to improve the dive situation, but that did not help too much with the pogo stick damping. Varying the oil weight allowed me to choose between a lively pogo stick or a stiff one, but I was never very happy with the fork's ability to track over bumps and dips. Getting onto the Bot's Dots and reflectors between lanes on the freeway would cause the bike's front end to jump all over the place.

    About 15 years ago, I gave up and took the forks to Race Tech. I sure wish I'd done that earlier. It would be a stupid thing to do, but I could ride a line of Bot's Dots all day if I wished - the fork just tracks right over stuff like that. Plus, the dive situation is much better than stock.
    Hmm..there is food for thought.
    My forks are Brembo. At lease the spares I have are. I have no pogo on the existing forks on the bike. Just softly sprung. Dampening seems fine and the stiction is blissfully non existant.
    Thanks for the input.
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

  12. #12
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    I think it depends on how hard you want to ride the bike. The RaceTech setup is very good. I installed it on my R90S. It is a fair bit firmer than stock, but I don't put that many miles on it and I like a firm suspension. I had the Progressive/7.5 set up on my R100 and that worked pretty well. I'd go with the latter if you do a lot of miles and/or if you do a lot of freeway miles. It also depends on what you're using in the rear as you want the forks to more or less match the front (I have Ikons on mine).
    61 Gold Star, 76 R90S, 03 CBR600RR, '13 690 Duke, '14 Street Triple R

  13. #13
    Registered User JGREGOR1.JG's Avatar
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    Quote Originally Posted by ccolwell View Post
    I think it depends on how hard you want to ride the bike. The RaceTech setup is very good. I installed it on my R90S. It is a fair bit firmer than stock, but I don't put that many miles on it and I like a firm suspension. I had the Progressive/7.5 set up on my R100 and that worked pretty well. I'd go with the latter if you do a lot of miles and/or if you do a lot of freeway miles. It also depends on what you're using in the rear as you want the forks to more or less match the front (I have Ikons on mine).
    Yes that's a good point. On my other bike I have progressive springs with ricor intiminators and 10w oil. Stiffish and well damped. On the rear are progressive 444 gas shocks with inertia control. Great sport setup and well matched.
    On the mono R100RS are stock all around. Very compliant and comfortable. I would naturally like to improve the suspension components because that's what I do, but sorting out 2 bikes in one riding season is very bad for my wallet.
    I don't tour on either bike. I just use them for enjoyable commuting daily with a mix of highway and back roads. I do see 85mph plus daily. Frankly both bikes are quite happy at that pace.
    Jim Gregory
    92 R100RS
    05 Sportster Roadster

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