I haven't tried to remove the countershaft pulley yet, but I was cleaning years of neglect and grime from the engine and noticed something odd. The pulley will rotate about 1/4" back and forth while the shaft and nut stay still.

Huh?

Were the pulleys made with lots of slack in the splines? Or are the splines worn? In less that 9k miles?

I'm converting to chain, so if it's just a worn pulley, no big deal. If it's something else, then  

I'm just tearing into mine for a RYCA kit.  if you get a chance, I'd like to see pictures of the pulley and spindle when you get inside.
Terry

Here are shots of my shaft and pulley splines.





There's a slight step on the outer edge of the shaft splines, probably word by the pulley rotating mack and forth. But I don't think it's enough to worry about.

Man, there's a lot of crud on things.

Id expect the shaft to be a good bit harder.

That picture of your worn out drive pulley is incredible BuckHMCC.  Really gone.  The thing about a splined shaft is that keeping the nut good and tight will not prevent that kind of wear.  The shaft and pulley must be designed with clearance in between the sides of the splines of the two parts so it can be assembled and then if sharp loads hammer it the thing will slam back and forth and it is going to wear out.  The wear rate will increase as the clearance grows because the hammering action becomes greater.  That's why they are fine for a long time and then seem to suddenly go.   Fortunately they obviously made the pulley with a softer material so the shaft is saved.

Unless this is an exceptional case, this pulley/shaft system is under-designed.  One approach would be to simply use a larger diameter shaft and more spline surface area to handle the load.  There are other ways to attach a pulley in high torque situations that are better and have been in use for decades.    A taper-lock style bushing and key system would be better.  

One thought about the chain conversion and I hate to say this since so many have done the conversion.  In view of the wear on the OEM pulley I think the drive chain sprocket would benefit from a wide hub, one that covers the full length of the splines.  A narrow steel sprocket might start wearing into the splines on the shaft.  Chain sprockets are usually made from fairly hard material.

Good luck with that chain conversion.  It will be nice to be able to change drive ratios.

Yes, I think you are right about the cost factor MotoBuddha.  The cam chain and tensioner system is another problem talked about in this forum that seems to fail prematurely.  Guys on this forum have made improvements to the tensioner in their home workshops so you have to wonder why Suzuki hasn't done something during all the years they have been making this engine.

It would be fun to tinker with the drive ratio and it is something I might do in the future.  I think I'll do a search on the topic.  This is a great forum, lots of good technical information.

I think we talked about the cam chain issue some time ago. IIRC, we concluded it wasnt a real maintenance issue years ago, but that they had likely started sourcing cheaper chains & parts in the mix. If I was gonna try to decide when that happned, Id look at when they changed the tensioner spring design & see if that was when, or if the changed the spring to try to compensate for changing to a cheaper chain a coupla years after they created a maintenance headache BY making that change.