Commando Timing Advance Curves Compiled (RevA)

Seeley920 said:

FWIW years ago I had points ignition on my race Atlas , fixed, no AAU. Set to 28 degrees and I could push start it in 3 steps, and it was the quickest bike off the line at Brands Hatch.....and that was in a mixed capacity grid...even starting from cold was easy....yes, the fixed ignition made it quick off the line and out of corners, but it didn't affect an 800rpm tickover and easy starting! (ok, I never had to kickstart it, but you can tell how easy a bike is to start even from a push!)

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In the mid '70s my 850 MkIII motor was the same to start as your Atlas, and set at 28 degrees max advance, it probably did not idle as well, certainly not at 800, but it ran 36mm carbs and 34mm ports...in '77 I fitted a Luca Rita (analogue) ignition that had come from Thruxton, thinking I would now have a fancy ignition curve....nope...Mr Williams and his friends shorted out the advance circuit and ran their fancy electronic ignitions fixed at full advance, just like they had their AAUs welded up before they ran electronic.....this was easily confirmed by the strobe, but also by Peter when I met him in '78.

I came to the conclusion long ago that you only need the advance curve to kick start and have an engine run at a low idle, however I will buy a good digital ignition with a well developed curve, since I can, and since I think modern fuels differ from that available in the '70s to the degree that a better ignition curve may help! Choosing the right one is perhaps more problematical and I think that having one with good proven base curves supplied, but with a capability to programme alternatives would be the best solution for a racer, and that any of the Pazon, TriSpark and PowerArc items should be good for road use!

BTW, comparisons with auto distributor AAU useage is not helpful because they normally used vacuum from the inlet manifold to retard the ignition as well as an AAU.