On the TY175, the kickstart stop, is pressed onto the kickstart shaft.  Sometimes the stop moves on the shaft, which can result in the kickstart smashing a hole through the clutch cover.

I wonder do any of the AT, CT, DT motors also suffer from this problem, and if they do, is there any way to prevent the stop moving? Many TY175 clutch covers are damaged due to this, and epoxy or bondo, seem to be popular methods of repair.

I wonder if they split & slip, same as happens on 465 & my yz490.
It seemed to be mainly because the stop was of some cast looking steel & the old stop on early shaft from various Yam trail bikes was stamped out of something much better & had just a steel look & not a sort of cast crap. So on my 490 i removed the stop off something probably an AG175/CT/AT old shaft by putting in the lathe & cutting in where its swaged on & it pops off the twisted spline. The one i fitted on was the same twist & size. So just timed it on the right spline then bronzed it on top stop it turning/twisting off. But tig welding would be good [wish i had a tig--wish i could afford oxy accetylene nowdays but cost to have it mostly sitting doing nothing is exorbitant.
If i can find me way into photobucket my pics off all that are there somewhere.

Ok found them from many years ago. Can see the crappy looking stop & what i used a better one from.

Not sure about the TY175 as I've never seen one with this issue...  I wonder if it's caused by well-meaning owners re-clocking the lever on the shaft to get more stroke out of the starter?  That causes the stop to take much bigger impact than it's meant to. 

I don't have much experience with the TY175, but on some models like the Husqvarna from that era, if you clock the lever on the splines for more lever travel it can seem ok but then that one time it doesn't disengage properly and severe damage results.

AT/CT kick start had several revisions to strengthen it.  Stop can slip but I've never seen one punch a hole through the cover. 

If AT/CT stop is in correct position on the shaft, I've seen the stop tack welded to the shaft with a MIG welder which seems to stop the slip issue on the AT/CT...

Thanks for your replies. I guess the stops actually break, when there is a major kickback? Its not possible to move a TY knuckle any further forward, as the lever is so close to the case. Kickers only engage, when the lever passes the 90 degree position. TY is very easy to start though, and this isnt a problem.

I have maybe 5 TY175 primary covers. Most of them have been holed close to the kickstart at some stage and been poorly repaired.

The kickstart itself is what goes through cover. TY kickstart is very different to the DT, AT, CT ones, and I would guess problems with the stop is the reason for this?

On motors, I am rebuilding I put a couple of depressions into the stop/shaft with a carbide burr, and then 2 small TIG welds with 308 filler. That seems to stop any further problems.