Starter Problem

[Idaho Red Rocket 3]

What is wrong when the starter spins and doesn't engage ? Friends Thruxton failed yesterday when he tried to start it. Made a scratchy bang then all you hear is the starter motor spin.

 

[Fingers]

I'm not with this starter but could be a bad bendix

 

[R-III-R Turbo]

sounds like a sprag clutch issue. had it on my old xvs 1100. if he puts it in gear, lets out clutch lever and pushes the bike back it will engage the sprags. then pull the clutch lever again and try start.
if that yields nowt i'd pull the starter motor out and see if it's spinning its cog ok

 

[Gregger]

First off, the starter rarely fails on the Bonnie. Having said that, there are two possibilities that fit the symptoms stated.
1. As R-111-R stated, it could be the sprag clutch in the starter gear train. The starter drive in the 790 and 865 parallel twins constantly meshes with the gear train. When starting, the sprag clutch allows the starter to spin the crank. Once the engine starts, the sprag slips disengaging the starter. The very odd time they can burn up or slip. Some guys have got lucky and gotten them to work by cleaning, others by replacing.
2. The other issue could be an idler gear boss failure. If often happens, usually after a severe backfire on start up, snapping the boss and causing the idler gear in contact with the starter to fall out of place. TRIUMPH TWIN POWER has a fix to help prevent this from happening. There are pictures in the link of what the broken boss looks like. Some guys have repaired the cases with the twin power fix. Others have installed a pin and drilled the cases to support it.

Anyway, hope this helps.

 

[1olbull]

sounds like a sprag clutch issue. had it on my old xvs 1100. if he puts it in gear, lets out clutch lever and pushes the bike back it will engage the sprags. then pull the clutch lever again and try start.
if that yields nowt i'd pull the starter motor out and see if it's spinning its cog ok

HUH???