Stupi question - Sprag bearing?

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Jon
Diana
Posts: 66
Joined: Mon Jun 16, 2008 8:56 pm
Location: Brisbane, Australia

Stupi question - Sprag bearing?

Post by Jon » Sat Jun 19, 2010 1:48 am

Went to start up my bike after finishing the wiring.

The starter is turning but motor is not so I figure sprag bearing?

Puzzling bits (to me):

If I put it in gear it will turn the back wheel with starter.

If I turn the back wheel in gear it looks like the flywheel turns through starter chain cover.

If I turn the wheel backwards in gear it tightens the starter motor drive chain.

Motor started and ran fine before tidy up.

Thanks in advance.
jon
1983 900 S2
1983 Mk III Le Mans
1992 Honda VFR400r
1976 CB550f

johnnyb
Mariana
Posts: 25
Joined: Thu Jun 11, 2009 4:58 am
Location: Sydney Australia

Post by johnnyb » Sun Jun 20, 2010 12:58 am

Hello Jon...I have had a couple of sprag bearings go on me. One went on me after I had the engine apart for a week fixing another issue and it failed when I wanted to fire it up to test my repairs. Lets just say I was not impressed of its timing.

By the results you mentioned there's a chance your sprag could have fallen apart and bits of the bearing could be binding the starter gear and fly wheel that's why you get what you do when in gear. Just remember if the bearing is in bits there is always the chance the bits can go into the crank case if the engine is run....not a good position to be in.

One of the bearings that failed in my bike totally ate itself and was in about 20 bits.

Hope I'm wrong and you dont have to replace the sprag..


cheers

john
John in Sydney Australia

Darmah 900sd
900ss

User avatar
Jon
Diana
Posts: 66
Joined: Mon Jun 16, 2008 8:56 pm
Location: Brisbane, Australia

Post by Jon » Sun Jun 20, 2010 1:49 am

Stripped it this am; Crank to primary gear key sheared in half, obviously not tensioned up correctly on last assembly.

Luckily shaft and inner bore primary gear are still serviceable.

Strange bit is that I took it for a lap around the block to check for unusual noises, wheeled it into the shed and started stripping it

Could have been a whole lot worse, fail on first decent ride somewhere.

Will post pic in tidy up in tidy up thread.
1983 900 S2
1983 Mk III Le Mans
1992 Honda VFR400r
1976 CB550f

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