RS and RT engines - differences?

[The Other PaulG]

I have always been under the impression that the RS had the most powerful R100 motor.

But looking at the Haynes manual, they quote the same:
* bore/stroke
* carburetor size
* valve sizes
* year for year, the same power and torque figures (suggesting the other engine internals are the same)

But didn't the RS have different pistons, for instance?

The reason I am asking the question, is that I have seen an RT in RS clothes which looks wonderful but I am wondering whether it would perform the same as an RS.

Haynes suggests that all other transmission bits, gearbox / final drive ratios look the same for the RT as RS by the way.

Cheers!

Paul G

 

[Rob Farmer]

Paul,

There were no differences in the 81 onwards rs or rt bikes. Both were sold as 70 bhp machines which was a little optimistic to say the least. There's a confusing amount of changes to oil coolers and fairing vent configurations over the years.

The earlier machines (pre 81) had different heads stamped with an rs on the rs model surprisingly. The most sought after heads in certain circles are the 77rs ones with a squish band.

The 78/79 rs engine is a gem if its standard and in good condition but you suffer the dodgy brakes and skinny swinging arm.

The later mono rs is easy to live with but is a bit soft. They made a pearlescent white one that looks great.

 

[The Other PaulG]

Many thanks Rob, that is really useful, I appreciate you taking the time.

Cheers,

Paul