First thought I had another sprag gone bad so searched for another spring and installed it.
Started once and all was fine. Let it warm up and cool down. On the second attempt to start, started then the usual grind scratch chunk like the spring broke again. Took it apart and sure enough broken spring. After removing the hub discovered it still would not spin over just clunk clunk clunk. Figured I had damaged the starter when the sprag went bad again. Turns out the cog gear seems to be the issue. Turns very hard on the shaft and even with heating and a puller I can't get it off.
Anyone run across this before ?

Finally got it sorted

Figure it was over driven when the sping broke in the sprag.

Completely welded together. Could not get it apart even once out of the case.

Fortunately,although many models use the same part and it is readily available I had a donor 906 around


Morale of the story, don't bother trying to replace the sprag spring with a spring from an oil seal None of them are suitable. The proper spring is around if you look

Also SKF makes a replacement sprag but it will require you leave out the circlip to fit it all together

Hi Higgy.

Some time back I replaced the Sprag bearing with the KTM equivalent. It went in with the original spring that came with the bearing. It hasn't been a problem since. There was an extra clip on one side of the bearing, but it came off without too much trouble. It all just fitted!

When you say it was completely welded together, was that all the Sprag's, or was the whole thing stuck inside the gear?

Is the donor 906 additional to your 906, or just the one?

Cheers.

Nick.

Hey Nick

The sprag spring broke and locked up the drive so the Idle gear was spinning at engine speed which locked the idle gear up on the shaft. The donor bike is in addition to my 906 so yes I have 2 906. One red,the good one and a blue one I picked up several years ago to keep the the other 3( and many others from the Paso.org) going. An 88 750, a 90 906 and the 92 907. I have 4 extra sprag springs I got from a buddy in Ireland. The donor sprag and one newer SKF sprag just in case.


FYI the donor 906 is also a 1990