A forum for owners of Yamaha TTR250 trail and enduro bikes!

Bought a TTR recently and although the previous owner said the sprag was OK, it seemed to be making some noises when operating the starter which were extra to the usual bang on switch off 

Stripped it down today and found one of the most damaged sprags I have seen so far so it goes in my Black Museum! The inner cage had almost completely broken up and I can't understand how it was working at all 

I am confident that I got out all the bits and pieces of broken sprag and the engine is all back together now and the starter sounds much better and the bang has gone 

Slight problem with an occasional backfire through the carb which I thought was the usual rubber/metal separation on the carb stub but, upon inspection, that was OK and the culprit seems to have been one of its fixing bolts was loose causing an air leak - possibly. The engine had recently been rebuilt so I guess it was just an oversight on the mechanic's part. Got interrupted by visitors so it will have to wait until tomorrow to see if I have fixed the problem.

Another TTR came in recently with sprag problems which had taken a couple of teeth off the small starter gear and cracked the casing. I marked the cracks with black felt tip. See pics below.

So, if your sprag is allowing the engine to kickback and bang on switch off, replace it soon before you get extra parts damaged needing repair or replacement! It is a very simple repair requiring just a new sprag (one way clutch assembly) and, if you are unlucky enough to damage it on dismantling, a case gasket. 

See http://www.dirtybiking.co.uk/features/tech_stuff_2005_starter_rebuild.htm

Brian