HELP! Starter Gears

[spray____]

I've been having trouble with my 06' GS500F starting the last few weeks. It would make a noise like the starter was turning, but 3/4 times it wouldn't "catch" and would just sound like it's spinning freely. Now it's to the point where it will just spin freely 100% of the time. Cracked the side of the case open today to see what's going on in there. Thought the problem was the same as in this video (http://www.youtube.com/watch?v=GxS5yZ44AHU), but now it doesn't look like it.

Here are some photos and videos of what I found:

I tried rotating the generator to see if it's loose, but it's on there pretty good. From the first video, you can also see that everything works as it's supposed to until the smaller gears become misaligned from the front one. It looks to me like the smaller gearset is shifting forward, and becoming misaligned with the larger starter gear. So now I have some questions...

1) What is supposed to hold the smaller starter gears back in their place? Is it just the case pushed tight over that axel that takes away the free space? It doesn't look like I'm missing parts...

2) Is the larger starter gear supposed to have that much free play in it?

3) Any guess on if my assumptions are correct, or what else could be the problem here?

[adidasguy]

Need close up picture of your idler gear. It looks like the teeth are worn off. Teeth run the whole length of the smaller idler gear.

[spray____]

Does this help?






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[spray____]

I don't see any teeth missing off any if those 3 gears if that's what you mean.

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[spray____]

Anyone have any ideas? I loosely assembled everything and put it away because I'm waiting on some parts for valves right now. That seems to have fixed it and the gears are catching now, but I don't want to assume it's fixed without having any idea what was actually wrong with it.

[Big Rich]

I can't watch the videos at work. But could it either be a weakened battery not spinning the starter fast enough to engage the gear, or worn out brushes inside the starter motor?

[spray____]

I don't think so. Replaced the battery with a brand new one about a week ago (old one wasn't holding much of a charge) and it didn't help. I can hear the starter motor spinning, which makes me fairly certain it's working properly. For some reason the gears don't seem to be transferring the motion to the crankshaft. Generator doesn't appear to be loose. My thought is the gears are becoming misaligned somehow. The first video illustrates the gears becoming misaligned as the smaller set moves away from the engine, but I don't see how that could happen with the case closed.

Is there supposed to be that much free play in the large gear attached to the starter clutch? (2nd video)

[sledge]

Dogs are probably worn or broken/weak springs in the sprag-clutch.

Try replacing them, there is nothing to loose. Overhaul kits are available

http://www.wemoto.com/bikes/suzuki/gs_500_fk4_fk5/04-05/picture/starter_clutch_repair_kit/

[adidasguy]

Watch my video on a loose starter gear/magneto assembly. That might be it.
The idle gears for the starter are held in place when the cover is on so they are OK. The main starter gear can wobble a little as it is on a one way clutch on the crank shaft.
It can be loose or tight depending on temperature. Before getting permanently loose, it would sometimes catch and sometimes slip a little. It is a friction fit on a tapered shaft.

[spray____]

Thank you both for the responses.

Generator seemed on there pretty good, but maybe it could be tighter. Snow is here now so I've got time. I think I might pull the generator off and have a look at what's going on behind there. $50 for a repair kit isn't too bad if anything seems out of order.

[spray____]

Bringing this back to life for an update.

I spent a couple months waiting on parts and warm days so that I could work on the bike. I was also doing valves at the same time.

Seems like it was a case of a loose generator. I used the swingarm bolt and a custom cut spacer to pop the generator off. There were a few scratches and thing grey film indicating that it had been spinning freely. Used a bit of locktite and cranked it back on tight.

Now the bike starts without problems. Another one solved with the help of GSTwins!

[adidasguy]

One caution: it may come off again. The tapered shafts are supposed to be a dry fit. Locktite may soften when the engine gets hot (heat is how we break bolts stuck with locktite).
Anyway - been there - had my first repair of it come off in a couple weeks. So now I do what is in my video and they have been stuck on now for over a year. (Dry, cleaned with alcohol and scored with 2000 grit for extra gripping between the shafts.)
Interesting that they can come loose in bikes that are new, under 8k miles and never have had the covers removed. I guess the factory didn't hit it with an impact wrench for that extra bit of holding power.

[sledge]

Flywheels that have slipped should have the corresponding tapers lapped together, no Loctite, no wet or dry.

There is NO better method. Research it for yourself 

Example........ http://www.mopedarmy.com/wiki/Lapping_tapered_crankshaft_and_flywheel_surfaces_for_good_no_slip_bond

[spray____]

When I say loctite I mean on the threads of the bolt, not the tapered shafts. They were scored with a bit of sand paper, cleaned, and dried.

Are you saying there shouldn't even be loctite on the bolt?

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[adidasguy]

Locktite is like a lubricant until it hardens. It softens when hot.
If you torqued to spec, it is possible it was not enough because loctite is slippery Or that couldhave caused extra torque (I forget what it does in all cases)..
If you gave it an extra hit with the impact wrench you should be OK. Pretty hard to over torque that bolt to cause any damage.
If you are done and running, then leave it but watch for symptoms during the next few weeks of riding.

[spray____]

I see, makes sense...

Will do that. It seems to be ok now but that being said it hasn't even properly warmed up since I did all the work. At least if it happens again I know how to fix it and what to do differently next time.

Thanks.

[adidasguy]

Also, always start in neutral. Starting ingear puts stress on the crank and motor. And which way does the starter gear go? In the direction to loosen that bolt!
We don't have a key slot on it so even a tiny slip from lots of stress starting in gear will eventually make it come loose. (At least that's how I think it happens).

[sledge]

A) kludge it with sandpaper and Loctite, hope that it holds and live with the nagging doubt that it may fail again in the near future

B) lap the tapers together in the recognised manner and have the reassurance that its the most effective and reliable repair method.

In the article I linked to the OP makes the following statement......

I have read some research about "lapping" and it is a very complex engineering field.

He is absolutely correct and its a great pity that others don't seem to understand, recognise and even acknowledge this fact 

[Joolstacho]

Pretty straightforward task lapping the tapers ain't it!
I reckon maybe a deft little centrepot on the edge of the nut flange/stator might help ?
I did this on mine - useful even if it's just so I can check now and again to see if the bolt has moved at all.

[sledge]

Its the tapered interface that does all the work, the bolt only has to be snug enough to hold the flywheel on the taper. A lot of people don't understand this concept and make the mistake of thinking tighter is better.

SCENARIO
Flywheel slips or for whatever reason is removed and replaced with a mismatched one, damage to the tapers is not or is incorrectly addressed leaving it down on efficiency, bolt is tightened up as much as possible and taken way beyond the 120newts that Suzuki recommend. Owner thinks he has resolved the problem and goes off for a beer.

UPSHOT
The now over torqued bolt has stretched along the shank and cant hold the flywheel on the now damaged taper. After a while the effects of heat, vibration and inertia loosen it off and the whole thing starts again........only this time the taper has lost even more surface contact and loses even more efficiency. The now frustrated owner is out of ideas and thinks the answer is to hit the bolt even harder with a bigger spanner stretching it even more!

lap the tapers to give 80-90%contact over both surfaces
Check the bolt......replace if it has stretched or shows any sign of damage
Check the face of the flywheel boss where the bolts skirt sits, if its damaged rectify it
Dab of locking compound on the bolt to counter the long term effects of heat vibration and rotational inertia
120newts....no more

Its the only way