Hello from new owner of 1960 125 Sport

[BDang]

Hi Rick,

The head R bearing outer race is locked in the head with snap ring outside and a shoulder inside, and so I agreed that the cam shaft can slide thru the L bearing inner race, with its outer race locked by the interference fit. This arrangement also takes care the L bearing housing gasket thickness.

For the top bevel backlash issue, it must be the shim on the top bevel shaft, and not the cam gear since the gear is resting on the bearing inner race and so it can only be shimmer out but not in. The snap ring on the bevel shaft must be below the bearing to lock the shaft to the bearing. There could be shim on top and bottom of bearing to set the gear mesh, and if the top shim was incorrectly placed below the bearing then the bevel fear would be lower causing backlash.

I found there was little backlash on the bevel shaft itself, and don't know it comes from the two shafts coupling inside the sleeve, or from lower bevel and crank gear. Is there any detectable plays in the coupling?

With the degree wheel on the crank, and the TDC tool, I found my rough ignition timing set by the cam gear was not too bad, 16.5 instead of 18 degrees.

Sounds like I need to pull the head off to adjust the top bevel gear lash. I hope the 125 head has no head gasket as other single heads as I read.

Regards,
Brian