I had a similar problem as this when I re-built my A10, a 1952 plunger. At that time I was running a magneto too. I went back through the timing process again and this seemed to sort the issue. However, I think this can also be a symptom of a failing magneto. I know you said yours was re-built, but... My magneto started to fail last year and the symptoms were rough idle, poor pick up and occasional back firing. I have since switched to electronic ignition and this has transformed the running of the bike.

Hello Martyn. No probs - let me know when you are up and running. Also, I heard that the VMCC meet at a pub (The Goat) in Frognall 3rd Wednesday every month (still to be verified by myself). Cheers, Graham.

I used to work at the Champion spark plug plant in the Wirral before it closed, so I am a bit biased. I used to always use Champion in my bike until I went electronic ignition. SRM advised me to use NGK stating they were better suited to electronic ignition. Personally, I don't think there is a big difference. Go with what you find works best for your engine.

Hello paulski, I used a strobe no probs on my A10. I did convert to 12v though. Take a look at the strobe gun itself. Mine has a slide adjuster on it for different rev ranges. Could be yours in just set for the wrong rev range. Also check you have a good connection to the HT lead and spark plug. Alternatively, if she runs well just on mechanical timing then you could mark the current position on the fine adjust and tweak a little at a time. You only need to move it 1 degree to get two degrees of timing adjustment at the crank - at least that's what mine does. And to get final timing mine only needed the smallest of fine adjustment from the mechanical timed point - if that makes sense.

I can confirm that when riding a plunger vs a swing arm there is almost no noticeable difference. But Idie is right, if there is excessive wear then the rear end would feel a bit wobbly. A swing arm ensures that the wheel moves up and down in alignment on both sides, where as the plunger can have the wheel moving up and down sightly independently on each side - if that makes sense. But as I said at the beginning, if all components are in good shape then its all pretty tight and riding you can't feel much difference.

I don't know if its the same on a swing arm A10, but getting the rear wheel off a plunger is a piece of cake. The rear sprocket/brake assy stay connected to the bike when you remove the wheel, so no messing about with chains when you the need to remove the wheel. 

Hello all. My A10 has been fine, no noticeable difference since I started using E10. But I will be draining her down for winter, where in the past I haven't bothered. Not really sure the extra 5% makes a big difference though. Just being cautious.  Graham.