excessive "end float" on kick/layshaft?

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luckyed

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Greetings All, I was removing the gearbox outer cover to deal with persistent leak from kickshaft seal and noticed what looks like approximately .100 (3/32) inches or so of end float in the layshaft/kickshaft connection. I already knew about the slop, but hadn't yet zeroed in on the implications. I presume this is unacceptable?! Is there any specific wear or maintenance issue that is indicated by the extra play? It seems like the excessive play would contribute to the kicker shaft seal leaking, among other things.

I have a '72 750 with 19,000 original miles, but unknown history of gearbox maintenance (except for oil change when acquired). I have read many threads along with the Old Britts articles on the layshaft bearing issue and dismantling and reassembling the gearbox and have just started to pick up on the need to set the end float (with necessary shims) on the layshaft assembly. (I believe .005-.009 in. is the standard?). Where do the shims go?

Shifting has been crisp and clean, but a couple rides ago there were issues with getting stuck in gear. Then it went back to normal shifting. I pulled the clutch center, and the plates were in good condition with no oil fouling since a prior cleaning.

I currently have the primary drive removed for other maintenance, and have yet to ascertain the type or condition of the layshaft bearing, so would it be the general consensus that the next step would be to tear into the gearbox? I guess I already know the answer, but would appreciate any pertinent info or opinions, particularly on any specifics regarding the end float setting, such as where do the shims go in the assembly?

Three cheers for this Forum, a wealth of information for those of us who do our own work, along with, I would imagine, those who don't!
 
If it currently has a ball bearing, which came standard, on the layshaft that will fix the layshaft on that end and not allow it to float because the inner race of the bearing is stationary. The slop you are seeing is probably between the right end of the layshaft and the kickstart shaft. If you convert to a roller bearing on the layshaft you need to be concerned about float as the roller bearing no longer fixes the left end of the layshaft because the inner race can slide in and out of the bearing. The shims fit between the inner cover and the kick start shaft. Isolastic shims work well but need to have the id enlarged slightly with a dremel as the kickstart shaft has a concave edge and you want the shim to sit flat. I'm happy with 0.010 anything less makes me a bit nervous. Measure with gasket in place or compensate for it's thickness.
 
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There is debate about the necessity for shimming for layshaft end play.
If you do put them in, they go between the kickstart shaft and the inside of the inner gearbox cover.
 
Thanks guys. Excellent info. More specific than I was able to find searching.
 
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