I know it's an old post but it reminded me of my experience years ago.If the sprag 'flips' then it won't grip at all.
If it actually breaks as mine did with an almighty crunch, it locked the motor drive to the crank! I managed to free it by putting the bike in gear and then sharply pushing it backwards several times until the sprag eventually freed off and I could then kickstart bike.
Unaware of the level of destruction I rode home.
Stripping the primary, this was what I found...
This 14 sprag unit was the old 'split-cage' type. Thankfully the sprags are no longer made with the slots cut into the cage.
Mine locked up on me but released when I kicked started and revved a bit.........the first time. It happened again a few days later and it didn't release. I revved it to the point of blowing up the armature of the original Prestolite motor. Fortunately it led me down the path of finding a Dyno Dave starter, big battery, 3 phase alternator, and new 18 sprag and associated parts. It's been 100% reliable for years. The big alternator took a while to finally sort and I'm pretty confident the Shindengen regulator has finally resolved. Three phase open as described here: https://www.shindengen.com/products/electro/motorcycle/reg/
