BMW K bikes (Bricks)

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1Back to top Go down    Transmission! on Mon Feb 29, 2016 4:02 pm

bolka13

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Hello!

I have 1987 BMW K100RS wich have 5 speedtransmission.
My question is.
Does anyone know if there is any transmission with six gears, which could fit it in my 1987 BMW K100RS?

Thank you.

    

2Back to top Go down    Re: Transmission! on Mon Feb 29, 2016 4:22 pm

robmack

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A K1200 transmission and bell housing will fit on the K100 / K75 block, however you're going to have to modify the frame to adapt it to the transmission, figure out how to adapt the K1200 hydraulic clutch to a cable operated K100 clutch, figure out how to adapt the sprague clutch mechanism on the K1200 to the main drive on the K100, buy a complete K1100 paralever rear end to replace the K100 monolever.. It's been done, but it'd be cheaper to get rid of the K100 and buy an early K1200 to get the 6 speed gearbox you're after.



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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

3Back to top Go down    Re: Transmission! on Mon Feb 29, 2016 6:07 pm

92KK 84WW Olaf


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Plus I believe the starter and alternator cannot be easily removed from the K1200. On the K75/K100/K1100 you can do them while breakfast is cooking.....

We have debated the 6 speed gearbox fit quite a bit but the modifications are severe if you are starting with an 8 valve engine and Monolever rear end. If you have to do it start with a K1100??


__________________________________________________
1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 83,150miles
    

4Back to top Go down    Re: Transmission! on Mon Feb 29, 2016 6:46 pm

duck

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Put me in the "Why bother?" camp. K bikes are designed to run at high RPMs so although it may seem like the RPMs are high it is not going to hurt the bike. (It's not a Camry.) Plus you get more torque in the highest gear with a 5 gear trans.


__________________________________________________
Current stable:
86 Custom K100 (K75C fairing, K75 Belly pan, Ceramic chromed engine covers, 32/10 final drive)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
93 K1100RS
94 K1100RS
93 K1100LT
91 K1
93 K75S
http://www.ClassicKBikes.com
    

5Back to top Go down    Re: Transmission! on Mon Feb 29, 2016 9:44 pm

Holister

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If you're after a taller (higher) cruising gear you'll find there won't be a great deal of difference.
Top (6th) gear and FD ratios are not much different to the K100RS.

K100RS 5 speed GB and FD
FD ratio 2.82
5th gear ratio 1.666
At 100 kph you're engine would be doing 4100rpm*

K1200S 6 speed GB and FD
FD ratio 2.82 (I think its the same as the RS)
6th gear ratio 1.582
At 100 kph you're engine would be doing 3900rpm* Just starting to get a bit too low for cruising imo.
*these are rough calculations.

The K100 has only about 60% of the bhp of the K1200S and so not as capable to handle a taller top gear anyway.

Top gear on a K100 would be about normal when compared to other bikes in its class. The power band cuts in at around 6k rpm so you're better off keeping the revs up in my opinion.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

6Back to top Go down    Re: Transmission! on Tue Mar 01, 2016 2:30 pm

bolka13

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Thank you guys!
I'm just asking is that possible and I know, on this world is anything possible Laughing.
I think this modify is too much for me and I will pass.

I have another question.

Wich tires do you have on your BMW?

Thank you again.

    

7Back to top Go down    Re: Transmission! on Tue Mar 01, 2016 3:20 pm

88

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@bolka13 wrote:
Wich tires do you have on your BMW?
Pirelli Sport Demons for me every time. Lots of threads on the forum about it.

Likethisthread.


__________________________________________________
88....May contain nuts!

"The world is a book and those who do not travel read only one page." - St. Augustine from 1600 years ago & still true!

Bike: K100LT 1988. 0172363. AKA the Bullion Brick!
Mods: k1100 screen and stands

K1100rs 1995, Remus exhaust.
    

8Back to top Go down    Re: Transmission! on Tue Mar 01, 2016 3:43 pm

92KK 84WW Olaf


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Hi Bolka13

This is great fun. We love Worship when someone opens up the tyre debate.

88 and myself live not too far from each other...about 3 hours. We go on trips together......We don't get much snow here and not a lot of frost but would have road surface temperatures quite low in winter.

He swears by the Pirelli Sport Demons, rides all year and in all weathers.

Iam happy withBridgestone Batlax BT45, 110/90/18 front at 38 psi and 140/80/17 rear at about 42/45 psi on the rear. Using them for quite a few years but as I use the bike a lot 6-8 months would be a good lifespan for me.

We ride on similar roads and we are both happy......so to some extent its personal choice/price whatever.

And you will find others on the forum using different tyres.

All I can say is see what is best used locally to you. I live with about 1500mm rainfall a year so plenty wet weather riding. 88 has much the same up his way.


__________________________________________________
1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 83,150miles
    

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