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How much advance?

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How much advance?

Posted by George Phillips at April 16. 2017
I've conclude that my '55 ES2 (but it applies to all bikes) is running somewhat retarded. I started it on full advance with no problem. The question is, the book says 47º advance but that was for National Benzole Mixture (or similar). Do I have to set it differently for modern fuels? George

Re: How much advance?

Posted by anna jeannette Dixon at April 16. 2017

Hello, George, it's 38 degrees before top dead centre full advanced  

   yours  anna j

Re: How much advance?

Posted by George Phillips at April 16. 2017
Thanks Anna. As the book says 47 - where do you get your 38 from? Cheers, george

Re: How much advance?

Posted by George Phillips at April 16. 2017
By some strange fluke, Anna, that's what it is currently set at. It works out at around 11mm or 7/16" before TDC. It just seems a bit retarded. George

Re: How much advance?

Posted by Ian MacDougall at April 16. 2017

All of the Maintenance Manuals I have (c1950, 55/56, 57/58) quote 5/8" BTDC for ES2. The earliest manual quotes 7/16" for 16H.

Ian McD

Re: How much advance?

Posted by George Phillips at April 16. 2017
Yep. That's what mine say, Ian. But that's my point. That was then for the "then" fuel. Does it now change for current fuel? George

Re: How much advance?

Posted by George Phillips at April 16. 2017

Re: How much advance?

Posted by richard_cornish at April 16. 2017

Hi George,

  Yes you are right to question your ignition advance re.-modern fuels. Ethanol is an alcohol and if used in pure form you could run your ES2 up to 11 to 1 compression ratio. As for everyday petrol, the ethanol content is between 5 to 10%. The general rule is the higher the anti-knock value of the fuel is, the slower it burns so the old 5star leaded petrol burned slower than the 1940s "pool" petrol. This seems at odds with Norton handbooks which through the years mostly quote 5/8ths inch BTDC fully advanced, points at .002". As petrol seems to change every year at the moment you need to be aware you may need to adjust to suit. Ideally the bike should run at both extremes of the ignition lever movement at just over tick-over speed and kick back if you try to start on full advance. If possible stick to one brand and grade of fuel.

Regards, Richard.

Re: How much advance?

Posted by boo_cock at April 16. 2017

Set up your ignition with 5/8 advance or a little over, then when running at road speeds above 40 ish you should be on full advance. Then try retarding just a bit on the lever. If it improves performance then you need to retard a bit. Where it runs best, leave it there and measure how far advanced it is by doing the fag paper bit and a measure down the bore as with normal timing. Note the distance, this SHOULD be your optimum advance measurement. If it is too much advance you should feel it falter slightly and if too much retard it will not pick up. Reset to this number and off you go. Woopee!

Re: How much advance?

Posted by George Phillips at April 16. 2017
Thanks guys. All sounds sensible enough. I'll do it this week. A good excuse for more "test runs". George

Re: How much advance?

Posted by anna jeannette Dixon at April 17. 2017
Previously George Phillips wrote:
By some strange fluke, Anna, that's what it is currently set at. It works out at around 11mm or 7/16" before TDC. It just seems a bit retarded. George

 

hello  by some fluke that means I know something about Nortons  but keep on having fun    your's    anna j

Re: How much advance?

Posted by George Phillips at April 17. 2017
Sorry to disappoint you, Anna, but the fluke was that I got my calcs wrong (in allowing for the measuring stick being at 45º) and ended up with 11mm instead of 23mm. Mind you, now it won't start at all! It's now set at 23mm (along the stick which as at 50º above horizontal) which is equivalent to 16mm vertical. The saga continues. George

Re: How much advance?

Posted by George Phillips at April 17. 2017
BTW guys - any clues as to why it now won't start. I've re-set it according to the book at 16mm (5/8") vertically BTDC. Fuel is there, the plug sparks and there's no air blockage. What I've noticed: 1) timing chain goes from very tight to 1/2" free play; 2) there seems to be a click when the spark is generated 3) occasionally there is a big bang from the exhaust. I've re-set it several times but to no avail. Now at my wits end! George

Re: How much advance?

Posted by john_evans1 at April 17. 2017

I find it best to set up as per the manual.Go for a run then adjust the timing by ear if not happy with the performance..these are old bikes and wear inevitably sets in which changes the advance curve.

 

If it kicks back on starting then retard slightly until it stops doing so.

 

Works for me every time.

Re: How much advance?

Posted by Barry Carson. at April 17. 2017

Hello George, is the inlet cam wheel magneto chain drive sprocket fitted on its woodruff key ok.

 

Barry

Re: How much advance?

Posted by chris_haywood at April 18. 2017

Double check you've timed it below TDC on the compression stroke and not the exhaust stroke. Very easy to do and makes for very big bangs now and then.

Re: How much advance?

Posted by George Phillips at April 18. 2017
Thanks guys. All plausible reasons.Having slept on it (ie having been awake most of the night thinking about it!) I now think that I misunderstood the instruction "turn the contact breaker forward" ie clockwise. I have a horrible suspicion I turned it anti-clockwise. I'll be in the garage shortly and put it to the test. Cheers, George

Re: How much advance?

Posted by George Phillips at April 18. 2017
Sorted! As I suspected and as Ian Cordes guessed (in a private email) i was turning the contact breaker the wrong way. Doh! Now it sounds like a 500 Norton! Mind you, other than Anna, no one has answered my initial question. Do modern fuels require a different advance setting owing to their possibly different burn rate? Cheers, George

Re: How much advance?

Posted by ian_cordes at April 18. 2017

Seat of the pants should answer your original question, George.

For my 650SS it is recommended to retard from 32 deg to 30 deg, in order to compensate for lower octane fuel. It is way more highly tuned than yours of course, originally designed to run on 100 octane fuel, with a 9:1 CR, and lumpier cams.

If it runs ok, and sings up hills, I wouldn't alter it.

Glad you got it sorted. Ian

Re: How much advance?

Posted by David Cooper at April 18. 2017

It's basically a prewar engine, isn't it?  And before the war there were three grades: 68, 75 and 80.  Nobody used 80 (unless presumably they had sporting pretensions).  So what we have today is a good deal better than what it was originally designed to use.  So we can probably all safely use a lot more advance than the figures in our books  - until maybe later in the '50s and on into the 60s.  I'd set it at least 1/16 more advanced and then I'd play with the lever.   But it's your piston at risk and not mine so it's your call!

There is a great technical article about fuels on this very web site!

http://www.nortonownersclub.org/support/technical-support-general/leaded-unleaded

 

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