Norton mk 3 starter sprag gear jammed!

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Desmond Tui

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I am replacing My sprag Bearing after around 4-5 years and used very often till now when I hit the start while it may have been still rotating, and the sprag must have rolled right over. I stripped the side cover off and removed the intermediate gear, and backfire assembly so I could still use the bike.
I now have time to change the Sprag however I cannot remove the drive gear from the sprag assembly. This gear is light weight and looks easy to break if pulled. I have tried reverse rotation with the primary locked but it is not freeing up.
This must have happened before, can anyone help with how to pull the gear without breaking it? all advice appreciated cheers!
 
Kia ora Desmond and welcome.
I'm sure someone will be along shortly.
 
Ive had two flip, one of which broke apart and jammed things up. In both cases things came apart fairly easily so I'm not of any help on this, wish I could see it.
I vaguely recall using a screwdriver to pry the rollers around with the second failure. That sprag was supplied by Norvil and only worked for a couple of days before failing. It cost about $200 at the time and there was no warranty from Norvil, as I had not changed the surrounding parts when installing the new sprag. Those parts are pretty expensive as I recall. Dubious quality as well.

That problem occurred a few miles from home. I phoned my wife and had her bring some necessary tools, then did the work roadside.
This was about 17 years ago.
For the next twelve years the bike was kickstart only.
About five years ago I fitted an Ali-express sprag, $17. The old original, somewhat worn inner and outer pieces are still in place.
This $17 sprag has worked perfectly to date.

CNW Norton also has the MK3 starter parts available and they are high quality items.

Glen
 
worntorn said:
Ive had two flip, one of which broke apart and jammed things up. In both cases things came apart fairly easily so I'm not of any help on this, wish I could see it.
I vaguely recall using a screwdriver to pry the rollers around with the second failure. That sprag was supplied by Norvil and only worked for a couple of days before failing. It cost about $200 at the time and there was no warranty from Norvil, as I had not changed the surrounding parts when installing the new sprag. Those parts are pretty expensive as I recall. Dubious quality as well.

That problem occurred a few miles from home. I phoned my wife and had her bring some necessary tools, then did the work roadside.
This was about 17 years ago.
For the next twelve years the bike was kickstart only.
About five years ago I fitted an Ali-express sprag, $17. The old original, somewhat worn inner and outer pieces are still in place.
This $17 sprag has worked perfectly to date.

CNW Norton also has the MK3 starter parts available and they are high quality items.

Glen
Click to expand...
Glen,
Do you have a part number or a link to the Aliexpress sprag?
 
The drive gear is actually quite stong, see if you can get a three legged puller to grab the gear and push off the end of the crank. Using a bit of care and keeping an eye (even use a straight edge across the gear) on the drive gear so you dont distort it. It should work. Or Rig up a small slide hammer that engages with one or two of the six holes in the drive gear to shock the gear from the sprag mess. You might have to use both methods, set the puller up with some tension on and then use the slide hammer as well.
 
worntorn said:
Ive had two flip, one of which broke apart and jammed things up. In both cases things came apart fairly easily so I'm not of any help on this, wish I could see it.
I vaguely recall using a screwdriver to pry the rollers around with the second failure. That sprag was supplied by Norvil and only worked for a couple of days before failing. It cost about $200 at the time and there was no warranty from Norvil, as I had not changed the surrounding parts when installing the new sprag. Those parts are pretty expensive as I recall. Dubious quality as well.

That problem occurred a few miles from home. I phoned my wife and had her bring some necessary tools, then did the work roadside.
This was about 17 years ago.
For the next twelve years the bike was kickstart only.
About five years ago I fitted an Ali-express sprag, $17. The old original, somewhat worn inner and outer pieces are still in place.
This $17 sprag has worked perfectly to date.

CNW Norton also has the MK3 starter parts available and they are high quality items.

Glen
Click to expand...
Yes I have bought the Ali express sprag, just can't get the assembly apart. It is jamming the needle roller, and it don'!t
rotate freely either way
 
Desmond Tui said:
Yes I have bought the Ali express sprag, just can't get the assembly apart. It is jamming the needle roller, and it don'!t
rotate freely either way
Click to expand...
I replaced the gear and needle bearing when my sprag failed, I was concerned the sprag may have caused damage. This may be what you're finding.
 
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