Britbike forum Forums Thread Like Summary - Missing on D/S with Pazon?

Having installed new Amal 930's on the Norton, proceed to set-up.
Follow Bushman's procedure.
Start engine, intermittent miss and backfire on D/S, was running normally before carb replacement.

OK, back to first principles, start with checking timing.
Strobe normal on T/S, reflects misses on D/S.
?? Pazon is wasted spark, so either none or both sides should strobe the miss?

For more confusion on my part, back in 2013 Kommando wrote:
"I had the same as Rohan, boyer only sparking on one side, a dedicated earth lead from head back to battery cured it."
So a wasted spark system can misbehave on one side?

Then I wouldn't be looking at the ignition. There are many little things which can go wrong with a carb installation. Sounds like a small intake air leak to me.

On dual coils one coil is wired opposite polarity to the other internally so ignition spark current stays within the coil/head loop and so both always fire if the coil is good.

On twin coils you have a full loop including the battery.

With wasted spark you have double the ignition current than with points, on my bike the engine earth wire was failing and so when 2 coils fired there was not enough capacity for 2 sparks but enough for 1 spark so only one plug sparked. When I added the dedicated earth the capacity for 2 sparks was restored.

What gave me the idea was when I took the HT off the 'Good' coil and started the bike on only one cylinder the 'Bad' coil sparked well with none of the previous backfiring or no spark.


I did all that and changed EI completely, all made no change until I left the HT lead off the good coil and then I realised there was an issue further down the path and added a new earth wire, instant restoration of 2 sparks.