Replaced my sprag, now won't start...

[loply]

Hi folks!

I replaced the "sprag clutch" (one-way bearing starter clutch thing, connects starter motor to flywheel) on my Aprilia RSV and I'm having difficulties. The old sprag had worn out meaning the starter motor would spin without connecting to the engine.

I got a brand new one, popped the flywheel off etc, fitted it.

Reassembled and hit the starter button, the motor sounds like it's turning over but it doesn't turn consistently fast... It sounds like the speed of the starter motor is fluctuating up and down and never reaching full pelt. About half a second of decent motion, then it "stalls" (goes quiet and slows down) and starts again.

Basically it sounds like a flat battery but the starter goes up and down rather than consistent speed.

This is a brand new fancy pants Varta battery that was fine beforehand, and has been in my house on an optimate for a week. To be sure, I also used another battery from another bike (also 100% fine) and that was the same.

I stripped the whole thing (with much swearing!) and can't see any evidence of a problem, the sprag is still fine, no metal shards, it locks fine etc.

The only suspicious thing I did notice was that, despite using loctite 648 and torquing to 120NM with the crankshaft locked, the flywheel had 1-2mm of freeplay back and forth on the crankshaft?

Any suggestions what to double check?
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[Wafer_Thin_Ham]

Can you bump it?

To be fair the reason why it sounds like it's "flucuating" is probably because it's pushing those two big pistons over their compression strokes(Mille's are very hard on the starting system as you know). Mine used to sound like that before it caught.

I'd be surprised but have you tripped the tilt switch?
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[loply]

I've not owned the bike for long but I can say for sure it's not the normal sound of the started, if you heard it you'd instantly agree.

I checked the kill switch but not the tip switch, bike hasn't been horizontal or anything though.
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[Wafer_Thin_Ham]

[NiteMare]

Quote...

The only suspicious thing I did notice was that, despite using loctite 648 and torquing to 120NM with the crankshaft locked, the flywheel had 1-2mm of freeplay back and forth on the crankshaft?

Any suggestions what to double check?

Endquote

i'd definitely get that freeplay sorted before even considering firing the engine up, a flywheel that moves will eat the end off the crank ...

have you forgotten to replace a shim ??
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