advance retard on electronic ignition

As I am not really up on the workings of the electronic ignition, I was wondering if the advance retard mechanism is some programmed electronic function set to suite each type of bike it is fitted to. Ie each advance retard programme is set to suite the particular type of bike or engine it is fitted to. Can some learned gent explain this to me.
The next question is, watching the timing light, the advance retard on my bike goes from about 3degrees BTDC at idle to the 31 degrees at around 5000rpm. is this normal. I don't seem to remember it moving that much in the old days when they had the springs and fly weight.

nnnrh said:

As I am not really up on the workings of the electronic ignition, I was wondering if the advance retard mechanism is some programmed electronic function set to suite each type of bike it is fitted to. Ie each advance retard programme is set to suite the particular type of bike or engine it is fitted to. Can some learned gent explain this to me.
The next question is, watching the timing light, the advance retard on my bike goes from about 3degrees BTDC at idle to the 31 degrees at around 5000rpm. is this normal. I don't seem to remember it moving that much in the old days when they had the springs and fly weight.

Click to expand...

Electronic ignition is usually programmed by the manufacturer to suit the bike it is sold for. Some ignition can be programmed by the owner using simple software. Watching the strobe as you describe, it sounds like your idle is retarded at low rpm and 31 degrees at 5000. Perfect for a stock road bike.

I know it is meant to be less advanced at idle, what I was wondering is should it be that MUCH less advanced at idle ?. And thanks for the other info.

nnnrh said:

I know it is meant to be less advanced at idle, what I was wondering is should it be that MUCH less advanced at idle ?. And thanks for the other info.

Click to expand...

Retarded means no kick back. That's why they do it. What ignition do you have ?

nnnrh said:

I know it is meant to be less advanced at idle, what I was wondering is should it be that MUCH less advanced at idle ?. And thanks for the other info.

Click to expand...

Which particular "electronic ignition" do you happen to be talking about?

Its a Boyer, but wouldn't they all be programmed the same, there must be a set advance retard programme that is correct for each engine type which gives peak engine performance.

nnnrh said:

Its a Boyer, but wouldn't they all be programmed the same, there must be a set advance retard programme that is correct for each engine type which gives peak engine performance.

Click to expand...

No, it doesn't seem to work like that.
commando-timing-advance-curves-compiled-reva-t6488.html

The AAU is an excellent curve; I have never figured out why the E units don't just duplicate it exactly. It's excellent for starting and "All [advance] in by 3000" has been a "standard" curve for conventional 4 cycle vehicle engines for best power for a LOOONG time.

L.A.B. said:

nnnrh said:

Its a Boyer, but wouldn't they all be programmed the same, there must be a set advance retard programme that is correct for each engine type which gives peak engine performance.

Click to expand...

No, it doesn't seem to work like that.
commando-timing-advance-curves-compiled-reva-t6488.html

Click to expand...

The Vshape in the Boyer curve is the "tick over stabilisation feature" it alters the timing at low revs to stop the engine from stalling. Manet people get confused when they strobe a Boyer micro digital and see the timing shift all over the place at low revs. They need to read the Boyer instructions and set the timing oat the fully advanced mark "when the Boyer has stopped advancing" not at any set revs, usually The Boyer curve will flatten off later than a mechanical advance

nnnrh said:

I know it is meant to be less advanced at idle, what I was wondering is should it be that MUCH less advanced at idle ?. And thanks for the other info.

Click to expand...

As you can see by those graphs, 10 to 15 degrees at idle is common.

The old boyer MKIII analog is built to a very broad tolerance. According to Ernie Bransden, BSA Norton triumph are all use this same curve and can actually be all over the map as far as not being exact. The main difference is the ends of the wire connectors match the bike as listed.

If you want some of my test results, go to my web site and read my 2 articles.
http://atlanticgreen.com/boyerexposed.htm
http://atlanticgreen.com/boyerevolved.htm
My initial article declares my confusion as to how one advance curve is suitable for all nortons :?:
Well I found that one product has a whole variety of curves and could be on your bike. My original boyer bought in the late 80's still sits in the box on my shelf.

The previous graph on this thread claims to use my data (without permission I might add) and also is not correct or in agreement with my data. :roll:

Thanks for the info, it is quite any interesting subject and obviously not an exact science given all the different curves that seem to do a good job. That green V curve Boyer line would have been impossible in the old days with just springs and a fly weight. Thanks, seems mine is working just fine.

Nnnrh

Sorry to go off topic, but my b31 advance retard lever was a thing of wonder and I had no cable on my valve lifter it used to rattle your fingers something rotten when you turned the engine off. From memory, it's been a while,but when I think of it now I say thank the bejezoose for E.I. Who care what the curve is!

Big J at kickback city.

I have a Pazon on my Norton,strobe timed it and the bike runs beautifully. Easy starting ,good power all the way thru.I like it.

When I 1st started Trixie Combat she settled down to 450 rpm steady as a clock. A later found the trick the DPO did dialing in ignition for slow stop/go New Orleans city use with contact breakers and worn AAU, he'd set one side a bit retarded and the other a bit advanced for old school version of E.I. idle stabilization. I didn't notice hwy power lost but also didn't run it into 2S Combat rpm range over legal before other things deer and bad parts shut us down. When I put the point back right on the money Trixie would only idle to 600ish before tended to stall. This is way too slow to be good for the lifter and ring blow by but its so so pleasant to listen/feel now and then and just a thumb screw slide rise to bring up for real life road charging rpm 900-1000 steady as she goes and factory charger is up to keeping points firing on low charging rpm.

Analogue ignitions- such as an old Boyer , Pazon Sure Fire or a Lucas Rita - are not "programmed"

They are simply an off- on switch which turns on [breaking the coil circuit and causing a spark] when the output from the pickup unit reaches a high enough voltage.

The voltage required to turn it on depends on the manufacturing tolerances of the switching transistor and components around it as well as the operating temperature.

The unit advances the timing simply due to the fact that when the pickup unit [a two pole alternator] turns faster it creates a higher voltage so the threshold voltage is reached sooner in the revolution.

How much voltage the pickup unit produces is determined by it manufacturing tolerances, the pole spacing and again the operating temperature.

All of these different tolerances can greatly influence how much advance is seen and the shape of the curve. An analogue ignition never stops advancing as the rpm increases although the amount of advance gets very small as the RPM increases beyond the designed operating range.

This is why no two analogue ignitions give the identical curve.

That being said -there are a lot of analogue ignitions in use on mildly tuned bikes that give very good results. Mildly tuned engines are not at all critical to ignition timing and analogue ignitions are simple and hard to screw up.

That all changes when you have a high compression engine with intake and exhaust tuning designed to give maximum cylinder pressures and power. In those cases a set of points and flyweights or a programmed digital ignition is needed to provide accurate timing. Jim

Dave,

You stated in your post:

"The previous graph on this thread claims to use my data (without permission I might add) and also is not correct or in agreement with my data."

On 20 May 2010, and again on 10 July 2011 to include the Pazon Altair data, I posted a compilation of advance curves on a common graph, to facilitate comparison of these different EIs for the readers of this board. Of the curves compiled, only the TriSpark curve was privately supplied to me (by Ludwig; Jan was gracious enough to allow me to include his data on the graph). Some of the data was taken from your website in a posting by you. At the moment of posting you placed this data in the public domain, obtainable by anyone on the planet with an internet connection. Public domain information does NOT require an author's permission to access or use. It does require, as a courtesy, a citation identifying the source. Your name is displayed on the graphs as well as in the body of the postings.

You presented your data with an arbitrary reference level, and it had to be adjusted to crankshaft speed and degrees, and shifted upward to match the spec on each EI (e.g., the AAU curve attains 28 degrees of advance at 3000 rpm), so that all curves could be directly compared. My curves derived from your data are accurate, your snarky comment notwithstanding. If you wish to keep your data proprietary, don't publish it in a public document.