Compression PSI on an '81R00

[JUPITERAL]

Having a valve job done. Does anyone know how much compression P.S.I. an R100 is supposed to put out ? Thanx

[20774]

A rule of thumb is one atmosphere above the compression ratio, converted to psi. For the '81 R100, the compression ratio was 8.2:1, so 9.2 times 14.7 is something like 135.

[20774]

I got my numbers from here for an '81 R100:

http://www.bmbikes.co.uk/specpages/R100.htm

The 9.5:1 was prior to the detuning that began in and around '78. LKChris seems to have this down cold...but I'm pretty sure they detuned the bikes in the early '80s.

[jforgo]

My 1980 R100RT already has the 8.2 pistons - they stayed thru 1984 for US bikes. unless, of course, your bike is Euro, or previously modified