If your on facebook, join the airhead association. Also next Sunday is airhead day at Sammy Millers Museum, there will be plenty of RS there.
R100RS - which year was the 'best' year?
- Thread starter Bonzo
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Bonzo
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Cheers casbar - unfortunately I don't do facebook, so I'm sure I'm missing out on lots of stuff.
I notice you're in Salisbury. My daughter lives there. Beautiful place.
My understanding is that the light flywheel revs better and easier where as the heavy flywheel keeps engine revs up longer which is better when trailing long
Heavy flywheel gets away with lower tick over revs but is more sluggish in acceleration.
Better engine braking, less agile.
The most noticeable change with a heavy flywheel is the driving behavior.
With heavy momentum, you have the Bulldog tractor single cyclinder behavior when shifting.
The flywheel mass retains its angular momentum longer due to the greater mass and it passes this on directly as thrust when shifting up. Unfortunately, the slower accelerating mass also has an effect when downshifting, which can sometimes lead to fun as the wheel stands still and slides in wet conditions before tight bends.
Shifting with heavy momentum requires a finer "foot", as you have to have a feel for the optimum shifting speed and the shift jumps. You simply can't shift gears when you want to.... similar to the Bulldog tractor mentioned above!
I suspect that the gearbox is also subjected to more stress due to the coarser gearshifts.
You can almost ride the light swing like a more modern bike and even shift gears in curves, even without a clutch if necessary.
Last edited:
Bonzo
Registered user
Great explanation albatross, thank you 
The very first original 1977 silvery blue RS had spoked wheels with a blue pin stripe around the rim. They also had 5BHP more then the models that followed. I’ve had several RS models, my favourite was the 1978 Motorsport, I had two of those, had a later smoke red model, a blue/silver special edition, I had a strange black with brown metallic flake paintwork, and a dark blue metallic 1982 model I bought off Bike magazine, never raced or rallied .. later on I always fitted K 75S handlebars as I found them far more comfortable
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I prefer the pre 79 bikes(heavy flywheel.)
Spoke wheels,ate calipers etc,.(I’d replace master cyl and ignition)
79 bikes were a transition into the later ones.
They had a “ beancan “with a set of points/ condenser inside.
Not long after the bikes went to electronic ign ,flat air filter and snowflake wheels..
Whilst the later bikes may well be “technically “ improved ,I think the earlier ones have more character.
Also be aware,the fairing is quite a heavy affair which does the forks no favours.
It can make the “experience “ a bit noisy as it seems to send motor noise up to the rider.
It’s also been described as riding with your hands in a washing up bowl as the bars are very narrow.
Once moving though you can cruise all day on these bikes with good wind protection.
Spoke wheels,ate calipers etc,.(I’d replace master cyl and ignition)
79 bikes were a transition into the later ones.
They had a “ beancan “with a set of points/ condenser inside.
Not long after the bikes went to electronic ign ,flat air filter and snowflake wheels..
Whilst the later bikes may well be “technically “ improved ,I think the earlier ones have more character.
Also be aware,the fairing is quite a heavy affair which does the forks no favours.
It can make the “experience “ a bit noisy as it seems to send motor noise up to the rider.
It’s also been described as riding with your hands in a washing up bowl as the bars are very narrow.
Once moving though you can cruise all day on these bikes with good wind protection.
I've got both the light and the heavy flywheel, and converted a heavy to a light flywheel (but not the other way). I've tracked a converted bike.
The light flywheel is great for spinning the motor up quickly. I got my converted R90S up to red line in top gear on a track easily.
You can talk about agility and Bulldogs but it is down to the mechanical basics. Large flywheel = inertia. Inertia is bad for acceleration and equally bad for deceleration (so no better engine braking with a large flywheel; ask Newton). As someone on another thread said, an R100 with 40mm carbs is rougher than one with 32mm carbs. My R90/6 heavy flywheel is lovely and smooth but not as energetic as a light flywheel model. Depends on your expectations/likings.
Brakes. My opinion is that a well setup ATE is as good or better than the Brembo. Pad material, disc material and pressure in the fluid are the important things. A handlebar master cylinder seems to deliver in the latter respect.
Best to find one you like the look of, ride it and decide.
The light flywheel is great for spinning the motor up quickly. I got my converted R90S up to red line in top gear on a track easily.
You can talk about agility and Bulldogs but it is down to the mechanical basics. Large flywheel = inertia. Inertia is bad for acceleration and equally bad for deceleration (so no better engine braking with a large flywheel; ask Newton). As someone on another thread said, an R100 with 40mm carbs is rougher than one with 32mm carbs. My R90/6 heavy flywheel is lovely and smooth but not as energetic as a light flywheel model. Depends on your expectations/likings.
Brakes. My opinion is that a well setup ATE is as good or better than the Brembo. Pad material, disc material and pressure in the fluid are the important things. A handlebar master cylinder seems to deliver in the latter respect.
Best to find one you like the look of, ride it and decide.
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