Last June I did a compression test on the Zed prior to it being taken to bits over the winter.
No. 2 cylinder was a little down on compression when compared with the others and when starting this cylinder would often not fire without getting some heat in and cleaning the plug.
I’ve recently turned my attention to the engine with a view to getting it back in the bike ASAP. I checked the valve clearances and all was fine apart from the valves on no. 2 cylinder. The clearance on both of the valves was < 0.05mm and I could not get a feeler gauge in to check the gap.
After removing and measuring the shimms i have some on order that are 0.15mm thinner in the hope that this will open the clearance up to somewhere near tolerance (0.05 -> 0.15mm).
Fingers crossed this was the cause of the lower compression on this cylinder.