TIMING INDICATION AT IDLE

Setting the timing on my 73 750 with old style Boyer . Instructions say to set at 31BTDC then check at 5000 with a strobe, has anyone got a figure for what the ignition should show at Idle? The Strobe light I have (Gunson Advance)has an ADVANCE facility which allows you to alter the strobe flash and therefore check the timing from TDC without the need to rev it up to 5000. Has anyone used one of these and do you rate using it to set the ignition at Idle?
The bike fires up no bother without kickbacks or misfires and seems to run ok !

An analogue Boyer's advance curve is not predictable enough to be able to set the timing at idle. With the timing at 31 degrees at 5000 the idle timing may be anywhere from about 5 to 15 degrees.

7 would be about ideal.

I would not count on an adjustable timing light being correct on a twin either. They are usually designed for 4 to 8 cylinder engines. Jim

Thanks for the input Jim, the light did seem to work pretty well but I can see what you mean about the timing being a bit erratic at idle!

willy mac said:

Thanks for the input Jim, the light did seem to work pretty well but I can see what you mean about the timing being a bit erratic at idle!

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Some adjustable advance lights will work on a Norton. I have a Snap-on and a Craftsman that are not accurate if the advance dial is anywhere except at zero. I have an old Sun adjustable that seems to be accurate when I use the advance settings but it will get very erratic when I rev the engine over about 4000 rpm. The only really accurate light I have is an old MSD light with no adjustable advance. It works at any RPM but you have to have a degree wheel on the crank to use it except in the limited range of the factory marks [which may or may not be accurate]. Jim

Hi willy,
Here is a link from the NSW Norton owners club that will be helpful.
Helped me sort mine out.
Sweenz

http://www.nocnsw.org.au/technical/igni ... ando-boyer

Some adjustable advance lights will work on a Norton.

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I bought one of the low voltage adjustable types a few years ago just so I could time without a mains supply. With the rotary switch backed right off it matches exactly my old mains connected model. However, it is very easy to knock the knob from the zero setting as it has very little resistance. What is better though is the inductive pickup for the HT lead. Not sure what the idle advance is as its off the mechanical scale in the primary cover and I haven't bothered to figure out how to use the advance/retard adjustment though I recall that you do need a full scale down to near zero, or at least 7-8 degrees for it to work. Probably better marking the stator with TDC and 31 deg and leave the primary open for checking?
As a matter of interest I checked my timing recently and it was retarded by 4 degrees at 4000 rpm and from 1500, the lowest I read. Retimed to 31 deg at 4000 and it was not so nice to ride, very coarse and rough and didn't go any better. Just backed off 2 Deg and its better. That's with the stator marked for a true 31 deg. and actually within a gnat's whotsit of the scale. No idea why it was off by so much, everything on the Pazon was tight, no slippage of the ign. stator plate or rotor.

Sweenz said:

Hi willy,
Here is a link from the NSW Norton owners club that will be helpful.
Helped me sort mine out.
Sweenz

http://www.nocnsw.org.au/technical/igni ... ando-boyer

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Hi Sweenz

A good articled that! And the other good thing is that it describes more or less what I've been seeing !

Thanks Again.