Starters are Mean to Me

[thatdood]

So,

My starter clutch stopped engaging on the crank today. I opened up the stator cover and found the bolt on the crank (#1.) to be loose. So I tightened it up, (I don't know what the torque on it should be, so I took it easy) put the cover back on, and gave it a shot. Nothing. The starter is spinning, but the clutch doesn't engage. The clutch (I'm assuming #2) slides down it's shaft and doesn't stay engaged to the crank sproket.

To illustrate:


The bolt on #1 won't stay tight. (Is it supposed to be?) and #2 keeps slipping off of it's shaft.

Can anyone help?


thatdood

[chef1366]

There is supposed to be a washer on #2 that keeps the shaft and gear from slipping into the crankcase cover.
Does #1 keep spinning or does it tighten and then loosen? Put it in gear and have someone hold the rear brake and tighten it to specs. Maybe try a little loctite.

[Big T]

#2 is not the clutch, it's an idler gear.

The clutch is the stuff shown in Chef's illustration.

If the rotor keeps turning, hmm, isn't there a woodruff key on the crank? If so. maybe that snapped off.

[tfb]

Alas, there's no woodruff key for the rotor to engage on the tapered end of the crankshaft -- just an 'interference fit' with that bolt #1 done up tight. And it has to be done up VICIOUSLY tight... I forget the exact torque (varies a bit from model to model anyhow) but it's a real tweak.

My suggestion is, remove the rotor and check the condition of the tapered end to the crankshaft. Almost certainly -- given that bolt #1 was loose -- the rotor will have been spinning on the crank. Which means that the taper may well be damaged.

In which case, clean it up the best you can, put the rotor back on and tweak bolt #1 up to the required torque. Then see if things engage properly.

[thatdood]

So,

I tightened the bolt on the starter clutch, but it came loose again. ](*,) So does anyone know the torque specs for that bolt? I don't want to overtighten it and then strip the threads on that crank.

That would suck.

thanks,

thatdood

[Steve]

I don't have specs for your '81 750, but my '82 650L calls for 65-72.5 ft.-lb., and my '82 850L calls for 65-72 ft.-lb., so I would feel safe saying that for your 750, you need 65-72 ft.-lb. of torque.


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