starter chain problem

[mollusc]

Put the bike in second gear on the centre stand, then bump the rear wheel forwards.  Watch the vanes of the alternator through the ventilation holes.  If the alternator turns, the starter chain is intact and the trouble is with the starter itself, or the starter clutch is freewheeling.
Starter clutch problems are pretty rare, but not unheard of.  Still require engine disassembly to fix though.

[Hend238]

Thanks mollusc for the troubleshooting advice.

I did pull the starter and tested it hanging from the power cable and grounded to the brake pedal. Seems to work just fine. No RPM indication as you'd expect.

I'm not sure how exactly the mechanics/wiring works for the RPM reading. A very brief glance at the wiring diagram shows that the coils are in that circuit. I can't visualize mechanically why I'm seeing RPM when I hit the starter though. Something is rotating to generate the signal and I'm worried it's a freewheeling starter clutch that is allowing this.

I'll take a look to see if the alternator rotates to rule out the chain or not.

[mollusc]

RPM signal comes from the spark unit, I believe.  It's based on how quickly the engine is firing.
The starter motor can spin freely if there is damage to the starter pinion (or the pinion is missing entirely) -- or it can be a chain or clutch issue.

[Hend238]

Ok so I rotated the back wheel and the cooling fins rotate.

The starter is still sitting on the bench so I stuck my finger in the hole and tried to rotate the starter clutch gear. It rotates cw but not ccw. That seems like the clutch is working. At least in my world that's how it should work.

I visually saw the end of the starter pinion spin when I tested the starter. I had removed the little reduction gear off the pinion splines. Is it possible that somehow that reduction gear did not engage the clutch gear?

For what it's worth, I could NOT budge the rear wheel in 2nd. I shifted up to 5th before I could budge it. Initially I thought that maybe the chain was jamming up the works but in the end I got the wheel to rotate and the cooling fins followed.

[mollusc]

I recall that the little pinion can go in the hole either way around, but only one way will work.  Maybe that was the problem?  It certainly seems like everything else is working as it should.

[Hend238]

That's entirely possible mollusc. Winter 2021/2022 I had the starter completely disassembled for cleaning/rebuild because of an oil leak and could have put that pinion gear back on the wrong way. It IS installed as per the diagram but that's not necessarily the right way. It's the only think I can think of that may be causing my issue at this point.

I know what I'll be doing tomorrow...

[Hend238]

Well I'm at a loss. That starter pinion gear can only go on one way in order for the starter to fit properly. Flipped around, the starter will not seat fully. Anyway, all indications point towards a broken chain but that's contrary to the cooling fins on the alternator rotating when spinning the rear tire.

I swear I can hear and feel the pulse generator rotor spinning when I hit the starter. In my mind that is where the RPM signal must be generated which explains why I see upwards of 7000 on the tach. There's a piece of the puzzle I'm missing here. Guess I'll find out when I tear the engine down at some point. Probably this winter. Crap.

[Hend238]

Thinking out loud here so bare with me...

Is it possible there's an issue with the cam chain, its tension, etc? I mean if I'm seeing RPM then the crankshaft has to be rotating. It sure sounds like it could be. Maybe that would explain why it was so hard for me to turn the rear wheel in gear because the exhaust valves weren't opening and I was working against compression? Now that I think back on it, I could here a little hiss at the tail pipe when I finally got some movement at the wheel. The starter chain is still intact otherwise the alternator cooling fins wouldn't rotate with the rear wheel. All indications tell me the clutch is working properly. Too bad the starter won't turn over in gear without pulling in the clutch - to see if the wheel would rotate. I could cheat that but it would probably result in something breaking if my hypothesis is correct. I do recognize there are few holes in it though. Hmmmm.

[Pete in PA]

Would you normally see 7k on the tach. every time you started the bike? That's weird.

Turning over the engine with the rear wheel is very hard with the plugs in. I used to do this on various bikes I owned for valve checks.  I had to bump it forwards and backwards to move the engine.

Are we sure it's not a starter problem?

Starter clutches are also sensitive to oil type just like the main clutch.  What oil are you using?

How many miles on the bike?

[Hend238]

Nope. Never saw any indication on the tach before this issue. The longer I hold the starter button the higher it goes. Peak is around 7000. It happens quickly. When I tested the starter uncoupled from the clutch gear there is no RPM indication.

I can't see that there is a starter problem of any kind during troubleshooting.

The bike typically uses Motul 5100 10W40 semi synthetic.

24000 miles.

[Hend238]

It's possible that the starter clutch is slipping under torque from the starter I guess. I cannot move the clutch gear CCW by hand though.

[mollusc]

The tach gets its signal from the spark unit.  It only comes from the pulse generator indirectly, in that that is the source of the timing signal.
Can you take the oil pan off to see if the starter chain is intact?  (I'm not even certain if you could actually see it, but it might tell you something.)

[Hend238]

I understand the function of the pulse generator with regards to its timing signal to the spark unit. But I thought if the spark unit is receiving a signal from the pulse generator then maybe that's why I'm seeing RPM. I'm just grasping at straws/thinking out loud trying to figure out why I'm seeing indication on the tach. I just can't wrap my head around it. If I can understand that, then that may shed light on the larger problem.

Dropping the oil pan to see the chain? Perhaps eh?

[Pete in PA]

seeing 7k and not starting have to be related. Something weird is going on.

Have you tried to bump start it in 2nd gear yet?

[mollusc]

The tach doesn't have anything to do with the starter chain.  However, if things are spinning freely inside the crankcase, maybe the pulse generators are actually giving correct indications that you're turning over at up to 7k even though the engine actually running.
Another thing to do could be to have the bike in neutral and watch the alternator vanes as before, but have someone hit the start button.  The starter and the alternator run off the same chain so this would confirm that the chain is intact.
If the is the case, I can only assume that something major is amiss in the guts somewhere.