Starter motor not engaging sporadically

blade023 · Trackday Trickster Joined: 09 Oct 2011 Karma :

So I went to get some oil for an oil change, got on the bike and it wouldn't start. I pressed the starter button and heard a click, which sounds like the relay, but no other sound. Got my trusty multi meter out and checked; 12.something volts from the battery. So I decided to bump start it, which was touch and go (or not Razz

) as it's a carbed twin engine so I had to be careful keeping it running as it's been a little cold here lately.

I went round the block and came back onto the car port, and tested the starter (with the engine running) and it turned over fine. So I stopped the engine and tried the starter again; same thing. Putting the bike in gear and rocking it forwards seem to sort it, it started fine. I managed to get to the shop and back ok but got the same thing; to get the starter motor working I put the bike in gear and rocked it forwards, then it started ok.

So does anyone have any ideas about what might be causing this? It's the first time this has happened on this bike, but I had a similar thing with my last bike (125 with a copy of a cg engine.)

Before anyone says it, it's not the subframe. I've had it straightened since I got the bike. Cost me a couple of hundered but was definately worth it as the bike now feels a lot more ambitious and generally less aprehensive about life in general.
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MickC · Spanner Monkey Joined: 27 May 2011 Karma :

From what you say (rocking it in gear) it sounds like the starter motor isn't engaging/disengaging from the engine. Don't know what make or model you have, but try starting with the starter motor clutch assembly. It does seem odd that an oil change (assuming it's the right oil for the engine) would be the cause, were there any starting problems before?.
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blade023 · Trackday Trickster Joined: 09 Oct 2011 Karma :

Ed Case · World Chat Champion Joined: 01 Mar 2009 Karma :

These starter clutches rely on (usually) three rollers + lightweight springs locking by centrifugal force on a machined 'drum'. It sounds like general wear and tear on all three parts. Best get it seen to promptly because they can be prone to 'jamming' which has been known to quite literally 'explode' the starter motor and cause other peripheral damage.