Forum

[Thack]

jefrs writes: "
The decompressor is triggered below about 900rpm. "



Actually 700rpm, by design. "Could be anywhere" by implementation.

[jefrs]

re "Could be anywhere" - correct . The tacho on mine is trying to tell me it cuts in between 750-850 rpm. Of course as soon as it does cut in the revs drop.

Upshot is that if I set tickover at 1000rpm then if the revs drop below 900 (as they do in accordance with Murphy's Law) then Sod's Law says the decompressor will cut in and try to kill the engine. Tickover set to 1050-100rpm.

In days of olde, the decomp was also used to stop the engine with magneto ignition.

Automatic decompressor = automatic traffic light stall feature. Otoh, revving it up and dropping the clutch in 2nd has the wheel 3-ft off the ground, oops.



OT thought, if the Honda CB77 could manage 104mph with 28bhp and similar weight, is the RE not a wee bit under geared at 85mph tops?

[Presto]

Maybe that is the result you get when the main engine design brief is the sound the engine is to make. I mean the exhaust sound the engine is to make!