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Electronic ignition Dominator 99

Submitted by geoffrey_stovold1 on Thursday, 22 January, 2026 - 19:59
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Heavy Twins

Hi all,

A bike I bought a year ago is fitted with a Boyer Bransden electronic ignition. The bike starts easily, ticks over well and seems to have the sort of urge I might expect in the lower and intermediate rev ranges. Carburation seems spot on by the colour of the plugs. The bike seems unwilling to reach maximum revs and the top speed seems to be no more than 80mph.

I want to check the ignition timing, Because it is electronic I am going to have to use a strobe light (for the first time). Can anyone advise what the degrees figure is fully advanced BTDC? The book I have assumes static timing only. (9/32" BTDC)

If anyone else has fitted electronic ignition to a Dominator 99, what product did you use. I was s bit disconcerted to find that the kit fitted to my bike is for a BSA/Triumph. I am wondering whether it is retarding as the revs increase instead of advancing?

Any help or advice gratefully received.

Geoff

 

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Submitted by robert_tuck on Thursday, 22 January, 2026 - 20:50

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When fully advanced the timing should be 32 deg.   which probably equals the 9/32 advanced setting  you (mistakenly) quote as the static setting. 

Thanks for your reply. The 9/32" or 7.14mm is what is quoted in the 1960 Maintenance Manual and Instruction Book. See photo

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I am no expert but the way I have always timed old bikes is to statically time them at the fully advanced position (e.g. 9/32" BTDC). The figure given in the handbook is nearly always for the fully advanced position. It would either be necessary to wedge open the bob weights on an old auto advance/retard mechanism or set the manual adjustment on the magneto to fully advanced. With the piston set at the specified position, the contact points are then set just about to open (often using the traditional fag paper). In my understanding 'static' does not mean retarded it means what the word means. i.e. stationary, not moving.

Submitted by david_cooper on Thursday, 22 January, 2026 - 23:46

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Regarding timing..out of curiosity, which manual do you have?  My Haynes gives 32 degrees.  My F Neill also has 32 degrees, as does Bacon.
Since the plugs at 30 degrees off the vertical, piston drop gets complicated to calculate and to use.

If it gets up to 80 and no more, main jet might be the problem.  Are you certain the throttle and air slides go all the way up?

I agree there may well be other reasons for lack of top end performance.. I know the main jet is correct. I need to check carb for full movement. The only manual I have is the original Norton book, which assumes the bike has a distributor with contact points and coil.

 



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