Hitchcocks Forum

just to be clear for a green RE owner - Aethelric suggests to stop the bike on the decompressor to save the sprag .. in what way does this help the longevity of the sprag ? say compared to the kill switch ? mucho grassyarse

The sprag clutch can be damaged by the engine going backwards, even if it's just a small part of a revolution.

When the ignition is turned off, or the kill switch used as the engine slows to a stop there may not be enough momentum to carry the piston over its final compression stroke and it will bounce back down causing the engine to go backwards.

But it can be much worse. Operating the ignition switch or the kill switch cuts off power to the coil. This is what the points do to make a spark. You can generate a spark accidentally which is far too far advanced causing a "powered" engine reversal

Operating the decompressor prevents there being enough compression to cause a power stroke and the engine stops going forward.

The engine also tends to come to a rest around TDC in my experience, preventing wet sumping if your bike is prone to it.

thanx for that-

Using the decomp also helps with starting, open decomp, spin motor up and close decomp spinning flywheels have momentum up to prevent it kicking back