How does the starter clutch work?

[Anonymous]

So a bike starter doesn't work like an automotive one right? Like the shaft doesn't push out and then turn. So what happens when the starter turns the idler gear? At a certain speed the clutch engages? Sorry for the thinking out loud, but the bike I just picked up may have a problem with this part and I'm trying to understand it. Thanks for any clarification, Ed

[lhanscom]

The starter connects to an idler gear that connects to the starter clutch. This clutch is on the crank shaft between the mag for the stator, and the engine case. It can only spin one way, so it will turn the engine with the starter, but once the engine is started it will spin freely on the crankshaft. A sign that the clutch is having a hard time, is when you hear a clunk when trying to start the engine.

[Anonymous]

The bike I'm talking about doesn't have a starter right now, but the people that messed with it previously said something about putting in a starter (don't know if it was the right one) and having it just spin. Without the starter in place, should I be able to spin it in one direction and not the other? Or should it grab in both directions? So the clutch works by grabbing at low rpms and then letting go once the centripital force builds? Thanks, Ed

[lhanscom]

You can spin it in one direction, but not the other. There isn't anything that let's go with rpms.

[focus frenzy]

these and most bikes use what is known as a one way bearing.
it will spin freely one direction but locks up the other (correct) direction.
it is mounted to the back side of the rotor under the left side cover, they have three rollers with a pin and spring pressing in on the rollers.
they do eventually wear out,and the springs can break,or the screws that hold them to the rotor break or work loose and fall out, but they are pretty reliable and tend to last a long time.
one thing I have noticed here in the technical forum, is that there have been several people who were having starter problems and they removed their starter motors to rebuild them, and upon installing them back on the bike, the clutch fails to engage afterwords for some odd reason.

[Anonymous]

Thanks guys

[Big T]

I've been wondering why mine clunks occassionally - how do you fix that problem with the clutch bearing?? Replacement?