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Advance and retard setting

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Hello everyone.

i have just enjoined the club as I am in the middle of trying to restore my fathers Norton ES2 1948. I am currently having the magneto restored. We have also have the head reseated and new valve guides fitted to take unleaded. But I have come a cross a problem which I an unable to workout and that is setting the advance and retard setting is there anyone who could take through this step by step?

i would be very grateful

Jonathan

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I've noticed that you've had no replies (yet) to your query, Jonathan, so thought I give you a quick note. The lack of response may be 'cos a detailed account is quite long winded. In a nutshell here's what you have to do.Set the contact point gap (0.010 - 0.012). Remove sparking plug; poke a wooded pencil/chopstick etc into plug hole and rotate the rear wheel with the bike in say 2nd gear to bring the piston up to compression (check by looking at tappets). Mark a line on your pencil at top dead centre. Wind the rear wheel back wards a tad to get the piston to drop then come back up towards TDC. With your 3rd had hold a piece of cigarette paper in the points gap. You should just be able to pull the paper away as the points open at 5/8" inches before TDC with the lever fully advanced. You can check this by making a mark on your pencil 5/8" ABOVE your TDC mark and slowly winding the rear wheel forward until the mark is level with the lug hole (or whatever reference you used for your TDC mark). You adjust the "opening" position by gently turning the armature clockwise (from contact breaker side) having previously loosened the drive sprocket. When it's set, tap the drive sprocket gently onto its taper and tighten. This is a very quick crude method but it gives you an idea of the procedure. Some else may come up wiht a more accurate and more detailed procedure. George

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Hi GeorgeA huge thank you for your reply to this I'm very, very to you!!I will try my best to do I'm not trained in this but trying to get the bike running again for my dad. Thank you and take careJonathan

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Be prepared for that magneto sprocket to be off & on a few times before you get it right. It is either right or wrong, and with no fine adjustment available it can be a frustrating experience. Whatever rod you use to measure the piston position make sure it is a long one - you don't want to lose the rod inside the barrel when you take the piston to the bottom of the stroke. I use the steel inner of an old wiper blade as it is thin enough to get a true vertical measurement in the spark plug hole. Very few of us were trained in this, we just had to work it out as we went along.

Ian McD

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I'm just about to do the same, but intook the head off, which is very easy, and used a dial gauge to find tdc and put a degree wheel on the primary drive. Just got to buy some rizlas, but decisions, decisions,...... red, blue or king Size?!

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Definitely liquorice, Dan. They burn better! Seriously though, the reason I suggested a chop stick or pencil (a long one!) is 'cos if you drop it in it won't damage the cylinder if you fire it up to blow it out. Last resort I know but Jonathan admits he's no an engineer. Whiie I had the p/c case off I took the opportunity to check the ignition timing on mine by means of a home made timing disc but I was trying to keep it simple for J.

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Hi Ian A huge thank you for your reply to this I'm very, very to you!! I will try my best and thank you for the advice on the rod, I have ordered a gadget that fits in the spark plug hole and has measurement on it so hopefully this will help. Thank you and take care Jonathan

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Hi Jonathan, a reminder that the 5/8" before top dead centre is vertical movement of the piston. The spark plug hole is angled so the plunger movement you see in the tool will be smaller than the piston movement. You will need to measure or estimate the angle of the plug and apply some trigonometry to convert the 5/8" to the measurement you will see on the gadget. Apologies for the complication! This is why I prefer a thin rod that can be held vertical in the spark plug hole. Also, when you are doing this job I think that will be easier if you turn the engine using a spanner on the engine sprocket nut rather than via the rear wheel.

Good luck, and let us know how you get on

Ian McD

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Hi Ian

a a huge thank you for all the help and advice I'm very grateful. As all this is very next to me. Thank you for the advice on the rob for the barrel too!

Jonathan

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Hello everyone

a huge thank you to you all for the help and advice I'm truly grateful.

i think now the process is clear in my mind and I now understand the process and reasoning for doing this. I just had one last question on this. I understand that the piston has to be set at 5/8th before TDC. But this has to be done on the compression stroke of the piston. How do you know when the piston is travelling upwards on the compression stroke rather than the exhaust one?

Thank you once again everyone. I really think this form is great!

Jonathan

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As far as I can read here and I've read through a couple of times no one has told Jonathon that the setting is usually made at Full Advance whether the bike has an ATD (Auto Advance) or Manual advance...So Jonathon make sure the timing is fully advanced before setting it....either by turning the ATD or setting it at fully advance on the handlebar control lever.

BTW.....When the bike has a manual control I always set the lever just below fully advanced but set the ignition to the recommended advance...The reason is thus....Factory recommended settings are simply the best average setting and not necessarily the very best for your engine with different fuel types, mixture strengths,air temperature and altitude. So by setting the max recommended setting at just below the full range of the lever you have some further adjustment left to vary the ignition as you ride by the feel and sound of the engine. This maximises power, economy and engine life too ....Another advantage of this method is that actually setting the initial timing can be slightly less accurate as the compensation is available at the lever afterwards and, as explained, you can get it spot on by the engine feel...The ONLY disadvantage is that one can't simply just throw the lever to the end position and forget it, but in practice it's easy to find the best position when riding and one can home in on it nearly subconsciously.....Les

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I bought an ignition timing light, easy to see, accurate, bit pricey but worth every penny I think. Also it is really easy to forget to time on full advance and you feel a right chump when you realise too late.

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Don't forget though, when you choose your pencil, don't pick one with a rubber on the end......Wink

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Hi Jonathan

On the compression stroke both valves are closed so both pushrods will be in the down position and (if your valve clearances are set correctly) should rotate easily by finger pressure. On the exhaust stroke the exhaust valve will be held open so that pushrod will be raised and will not rotate.

Ian McD

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Les - I did actually note in my initial response "....You should just be able to pull the paper away as the points open at 5/8" inches before TDC with the lever fully advanced." so it was covered. That's an interesting point you make about have sone advance up your sleeve. I might try that next time. George

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My apologies to you George ...Indeed you did, I must learn to be able to read correctly....As regards to the extra bit of advance, I have since been told by a magneto specialist thatone is operating the mag just below the optimum output if this is done, But I have conjectured with him that if the same mag can start the engine at full retard (which must be way of optimum mag energy wise)and at leg kicking speed it would follow that at several thousand RPM at normal engine running speeds there is easily sufficient spark energy being created to provide perfect ignition at the plug....NB: the power produced by a magnetois roughly analogous to a dynamo ...the faster it spins the higher the voltage so I know there is no drawback whatsoever but you gain in having that bit of adjustment for optimum ignition timing....Les

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We're moving a bit off topic here, Les, but is it to do with spark power (mag speed) or spark timing, making for the optimum setting?

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The MO1 mags do indeed produce a better spark at full advance (something to do with magneto flux) which means that if you've got the confidence, they'll often start more easily in that position...but do follow through !

I'm rather with Les though. There are so many variables on the road such as fuel and inclines that I feel an experienced rider can benefit from going past the factory setting and advancing up to the point that a certain roughness arises before pre-ignition and then backing off a tadge. This isn't possible if full advance on the mag is full advance on the lever.

My experience though is limited to tight-wire advance and the '50s bikes have a slack wire, I believe. In those cases, it would seem a bit odd to tension the cable for normal running.

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Hello everyone

Once again a huge thank you for all your replies. The thinking behind leaving a little extra on the advance cable sounds like a great idea and I will attempt this.

I just wanted to go back to Ian's point with regards to the knowing when the piston is on its compression stroke or exhaust stroke. I under the valve is open on the exhaust stroke and if looking at the bike from the gear box side the righthand piston would be up. But as mentioned in posts here and other things i have read online. TO get the most accurate setting it is best done with the head removed. In this case how are you able to know.

I am sorry for all the questions. But I'm a total beginner in this and slowly building my knowledge on the bike. And after spending a lot to get the mag and dynamo restored just don't want to get it wrong.

Thank you all once again!

Jonathan

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Hi Jonathan,

If you are working with the cylinder head in place, then remove the cover on the side of the rocker box and observe the top end of the push-rods.

If you have removed the cylinder head then observe the tappets (bottom end of the push-rods) at the base of the cylinder. In either case you are looking for the one point in the cycle where both tappets are down.

It is probably slightly more accurate to measure the piston position with the cylinder head removed but if that is the only reason to remove the head then I would leave it in place. No point in creating extra work for yourself.

Ian McD

 

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