This last week I have had to do the Pinion bolt upgrade, due to the customery extrusion out through the timing cover.
I have a 2012 but the motor was rebuilt in 2014/15 with a new crankshaft due to original compensator issues.
Also had a Centa installed at that time
When removing the timing belt etc to do upgrade, the pinion sprocket literally fell off
It was a very loose fit with almost one tooth of rotation!
I thought this was strange?
The replacement pinion sprocket was a good interferance fit with no slop
Could this be to do with the crank size variation? or was it damage with bolt failure?
When loctite used on the new sprocket it was a good tight fit and as I feel it should be/have been.
Its raining so havent been on a run since upgrade, but the motor seems? to be quieter with regard to tappets etc!
When the pinion bolt loosens the bore of the sprocket is relatively soft and then frets and wears away on the shaft. This is what you have seen and not any difference in shaft diameters.
