Troubleshooting a JAP Special

[33d6]

Knackered is knackered. No matter what little bodges you perform the need to replace the worn parts remains. It’s one thing to do a temporary repair to get home or until replacements are available but anything else just makes the bike a misery.
Do a proper job of it. New parts.

[Rex]

Way back when these were just old bikes and things were done to eke out a little more life from them, the fix of drilling along the spline/kick starter interface and fitting a bolt, screw, roll pin whatever often featured in the "ten bob tips" columns.
Don't know that I'd want to damage old parts in this way now though.

[john.k]

Not strictly relevant ,but if you have a fine spine shaft and close down a matching spline with a clamped split ,the spline will eventually be sheared off as wear occurrs .............I used to see this quite often in a particular large truck steering ,where the sector shaft and drop arm were fine splined parallel,and eventually all the spline would disappear ...with noticable effects on the steering.