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starter clutch CB750F

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neat street:
Hi All
starting the engine is getting worse, push button, then horrible noise (sounds like starter clutch not engaging)? what parts would you suggest I should try and source to fix the problem? I think part No  28120300000 is the main item needed, but no stock anywhere that I can find (any ideas on where to get one). and is it an easy repair?
Thank you all in advance
John

K2-K6:
Before you get any further with parts can you be certain that the battery has enough output?  the starter drives the crank through a sprag clutch which relies on a mechanical pinching effect to transmit the torque,  if the battery doesn't provide enough grunt this clutch can slip and make a screeching noise.

Try it with jump leads from a car connected to see if it's any better,  if not then you're most likely into repair.

neat street:
thanks for your quick reply, the battery is new, and sometimes the starter will engage and turn normally then slip, other times (most) just slips (whining noise then clunky gear noise). I have seen clutch repair kits on fleebay, but not sure if I need to go deeper and get more parts (starter clutch itself?). If it is the starter clutch, anyone know where to get one from please? (DS and CMS no stock)

K2-K6:
The clunky gear noise shouldn't really happen without something being strange,  I've never heard one do that. You may have to remove the alternator cover to make sure nothing is badly wrong.
They are generally reliable as a rule but doesn't mean they can't go wrong. Don't know how familiar you are with the components,  the clutch effectively comprises a large gear rotating directly on the crank with a series of pinch rollers within that joint,  as the starter spins the gear then the rollers are used to pinch directly on the crank surface and lock the two together so there is no clutch in effect but just the small components (rollers etc) so I guess that is what the repair kits are selling,.

Can you hear where the clunking is coming from? It's not from the starter solenoid is it?

Bryanj:
If done early enough pins springs and rollers should cure it BUT i have seen the clutch assembly come loose on the rotor and/or break the screws, somewhere i have a NOS clutch outer. I have seen the big gear centre polished surface wear but not often

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