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BobL
26th Dec 2019, 11:00 PM
Not mine but my one of my brothers latest efforts at converting a 1981 R100RT into a cafe racer
My Hercus lathe and mill contributed to machining of some of the parts for this build

Before - minus fairing and seat
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After
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Some more details and close ups here
https://www.returnofthecaferacers.com/bmw-motorcycles-cafe-racer/joes-r100rt/

Optimark
27th Dec 2019, 09:48 AM
Very nice Bob, tell him he has done a very good job of what is (or was) a fairly pedestrian unit.

As he has removed quite a lot of weight, but still retained the 70HP motor, he could change the bevel drive for one that has the 1:2.91 ratio, this will lift his top speed from 190 km/h to around 200 km/h and first and second gear will still be wonderful. That drive will be marked 11/32 on the flat surface on the rear of the rear wheel bevel box. Maximum horsepower on the cam (if original) comes at 7,000 rpm, the redline for that motor was 7,300 rpm.

7,000 rpm should be able to be maintained constantly if the oil is kept to 10mm below the high mark. If the oil level is too high, the crank throws create too much oil mist in the crankcase and the crankcase ventilation system becomes blocked. The 1974 R90S was the first of the flat twins to have this problem, a mark 13mm below the top line was where the oil had to be kept below to maintain a constant engine speed over 6,000 rpm. I suffered from this problem once into WA crossing the Nullabor in 1976 and moving the pace upwards on the bitumen.

Interesting speedomotor, I noted that the speedo cable from the rear of the gearbox was gone, I assume he is taking the speed from the front wheel.

The chokes he has constructed, are pretty much what I did to all of my flat twin units. I usually used the top piece of an old car antenna. Using the knob of the antenna to pull up for choke and push down for off. His chokes look a lot better than what mine were though.

A /5 front electrical cover will fit and it is a cleaner look than the standard one with the vented side. I used a /5 with no vents on my 1975 R90S, 1977 R100/7 and finally, on my 1982 R100CS which meant that cover did around 900,000 klm's on those bikes, plus around 85,000 klm's on my R75/5 SWB. My requirements were not for looks, mine was to keep water from the points when crossing water.

Mick.

BobL
27th Dec 2019, 10:11 AM
Thanks Mick, I have forwarded your comments.

You are right about removing weight. He spent a lot of time completely rebuilding the rear end of the frame from scratch.

In your last paragraph do you really mean 900,000 kms?

Interestingly I was crossing the Nullarbor in 1976 on my old R60/5. Around Ceduna it was so hot (apparently it was over 50ºC) the only things on the road were air cooled motors, VWs and non water cooled motor cycles. The cross winds from the north were so strong we had to ride at a side angle to ride in a straight line.

Bro has converted a couple of other bikes including a Moto Guzzi, a KTM which he has now sold, another beeme,r and recently purchase another beemer in a shocking state that he bought for $300 in the pipeline. His touring bike is a 1996 Yamaha RTS1000 - boy is that a weird ride - very comfortable though.

383962 383961 383960

Optimark
27th Dec 2019, 03:54 PM
Yes, I did mean 900,000 km's.

R90S owned for 15 months, travelled 118,000 km's.

R100/7 owned from 1977 to 1982, travelled 350,000 km's.

R80 G/S first privately owned one in Australia, 1980 to 1982, travelled 125,000 km's. This was a great bike, but 3 clutches, 3 rear suspension units, front forks replaced, 2 speedometers, 1 exhaust, 1 seat, 1 rear sub-frame, tank mounts replaced. As well as the rear wheel being replaced along with the bolts that held the rear wheel being replaced with Loctited studs with bolts. Apart from that, it was a brilliant machine. Crossing the Nullabor I once made around 140 km's before running out of fuel. The gearing, combined with a ferocious headwind and holding the throttle flat out, will do that.

R100CS 1982 to 1998, travelled 305,000 klm's.

I've crossed the Nullabor around 36 times on motorcycles, first time was on a Vespa motor scooter in 1968. I carried two kerosene tins of fuel between my legs for the long spans between fuel stops. :D

Mick.

Ps: I sort of lived on motorcycles for quite a period of my life, in case that wasn't obvious.

GuzziJohn
27th Dec 2019, 05:20 PM
Bro has converted a couple of other bikes including a Moto Guzzi,

383962


Any more pics of this one.

BobL
27th Dec 2019, 07:32 PM
Any more pics of this one.

He has vids off most of his builds on his youtube channel
https://www.youtube.com/user/fangitjoe/videos

This one has features the Guzzi.
https://www.youtube.com/watch?v=HrsU1IdG9KE

GuzziJohn
27th Dec 2019, 08:43 PM
This one has features the Guzzi.
https://www.youtube.com/watch?v=HrsU1IdG9KE

Beautiful

bwal74
28th Dec 2019, 08:48 AM
Yes, I did mean 900,000 km's.

R90S owned for 15 months, travelled 118,000 km's.

R100/7 owned from 1977 to 1982, travelled 350,000 km's.

R80 G/S first privately owned one in Australia, 1980 to 1982, travelled 125,000 km's. This was a great bike, but 3 clutches, 3 rear suspension units, front forks replaced, 2 speedometers, 1 exhaust, 1 seat, 1 rear sub-frame, tank mounts replaced. As well as the rear wheel being replaced along with the bolts that held the rear wheel being replaced with Loctited studs with bolts. Apart from that, it was a brilliant machine. Crossing the Nullabor I once made around 140 km's before running out of fuel. The gearing, combined with a ferocious headwind and holding the throttle flat out, will do that.

R100CS 1982 to 1998, travelled 305,000 klm's.

I've crossed the Nullabor around 36 times on motorcycles, first time was on a Vespa motor scooter in 1968. I carried two kerosene tins of fuel between my legs for the long spans between fuel stops. :D

Mick.

Ps: I sort of lived on motorcycles for quite a period of my life, in case that wasn't obvious.


This post made my day!

Ben.
Former Triumph Sprint ST955i rider - many a day spent with the electricals pulled apart.