To put it bluntly No. TDC is when the piston has risen to the top of its travel. The distance between the wrist pin and the crown of the piston is immaterial as tdc is when the big end has reached as high as it will go. However it may make a difference depending on how you are measuring TDC. Does the piston rise above the barrel at tdc? If so how are you securing your measuring tool before you introduce the 7/16 spacer? You are turning the engine backwards beyond the firing point and then coming forward to 7/16 before tdc to eliminate backlash aren't you, making sure points are fully advanced. I don't suppose the points have lost their 15 thou gap have they?Expat wrote: ↑Sun Sep 10, 2023 2:14 pm Nothing concerning ignition timing has been altered or slipped since last riding, so I was thinking the piston must be taller above the wrist pin and that the ATD and cam assembly needs to be pulled off the drive taper on the crank and refitted in a more anti clockwise position.
Does that make sense?
I am running out of other ideas but as you did not change anything on the points and it cannot be anything to do with the piston ...........