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Auto advance and electronic ignition

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Hi. I’m going to fit electronic ignition (probably Pazon) to my Dommie 99 basket case once it’s rebuilt.

I know that you have to do ‘something’ to fix the auto advance unit in one position, but I’m not sure whether it needs to have the spring retaining arms fixed in the ‘wide open’ position or the ‘’at rest’ (unoperated) position. I therefore Googled it and guess what ... there were some people advising welding or lock wiring the arms fully open and some advising welding or lock wiring them fully shut - isn’t the internet wonderful? (or dangerous, make your own mind up on that one). So I’m still none the wiser which way to fix the ‘spring retaining arms’ of the auto advance unit. Also, is lock wiring them in the appropriate position ok? ( I don’t have access to a welder) or should I really go for the welded option?

The other option, so I’m told, is to try and find a manual advance magneto sprocket, but I’ve looked in the usual places and they seem in very short supply.

Finally, does that ‘C’ shaped steel  washer need to go back under the fixing bolt - is it acting as a lock washer for the bolt?

Many thanks

Regards

Tony

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One problem with lockwiring in fully retarded, could be that if the lockwire fails, you might get a vigorous kickback when starting it. There might be a reason unknown to me why one should be better. If I ever comes to finalizing my longtime Dommie project, I'll choose the one easiest to do.

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I am in the process of putting the auto advance unit back on my RE Bullet and timing magneto - Lucas SR1. The workshop manual tells me to lock the auto advance unit in the fully advanced position using some wire with piston appropriate distance before TDC. It goes on to say attach auto advance locked at fully advance as points are just opening when fitting on magneto shaft. I have a thick wire from  the battery cable section of the wiring harness from another bike and folded over on itself, This was then pushed in to the AA unit to hold springs in open position and it does holds the AA unit in fully advanced fine. Obviously remove wire when on shaft securely. There are also some videos on You tube which I accessed through 'magneto timing' in search box. The ones seen are consistent with what is said above. Anyway trust this helps and good luck. Hugh.

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hello Now If this was me I would go for the CDI ignitions from Electexworld.com STK102D with lighting this type is more reliable  than any other electronic ignition systems  and replace your alternator as well as the ignition system,  at the near same cost as any other At, 235 Pounds for the complete kit,,                                     yours  anna j

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I can't remember whether mine is locked at present. I just found a picture from 5yrs ago and it seems it is.  But for a long time I ran it with the springs removed. As soon as you kick over  it spins to full advance anyway. 

There isn't a lot of space for the wire if you go that route. Don't weld it up..that's irreversible.

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Just a thought regarding these conversions.

The Magneto has a taper shaft for the Advance / Retard unit whereas most of the 'ready to fit' conversion kits come with a parallel shaft the same as a Distributor.

Another point of interest. The 'C' shaped washer does need to be fitted under the fixing bolt. Otherwise this bolt will bottom out without holding the A/R unit firmly in position.

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As above do fit a manual sprocket IF you have a tapered shaft coming in to the timing chest. Welding ruins a decent adv/ret unit, wiring will come undone etc.If you buy an aftermarket housing device (often called a mushroom a la Mercury late Atlas) to hold the Pazon or BB ignition then you will be faced with a parallel shaft a la dizzy. But if you have an 18D2 dizzy I can put BB electronic ignition in that.

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Hi David, Looking at your timing side reminds me its been too long since I checked the cam chain.Thats loose!.

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Thanks to everyone who has replied. I thought fitting electronic ignition was going to be easy - just buy one of those alloy mushroom things to replace the magneto and everything else will fall into place (well, what’s wrong with a bit of blind hope now and again?).

Now I learn that the electronic ignition  ‘mushrooms’ have a parallel shaft and so my mag auto advance unit won’t fit - oh bu**er!

 So I guess that I need to look for a distributor sprocket (with a parallel shaft), is that correct? If so, does anyone know of where I could get one -   I have a ‘spare’ auto advance unit for a mag now, if anyone wants to swap. Al, thanks for the offer of building a BB unit into a dizzy, however, unfortunately, I don’t have one.

Thanks again to one and all for all the info and help.

Regards

Tony

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Worth calling the various suppliers and asking re taper or straight. I'm pretty sure that I bought my Boyer equipped 'mushroom' from Norvil and I simply swapped my mag sprocket over (someone had fitted a manual mag to the bike before I got it), but that was a long time ago. Phil says MOST of the mushrooms have parallel shsfts, but that doesn't  mean all?

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Do they really sell things that are grossly unfit for purpose? My old RITA has the same taper as Lucas magneto. What's the point of selling something that doesn't fit? And who is buying and why? Just done a search and all the pics I see have a taper.

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I believe you refer to the type fitted to late Atlas, 650SS and early Commandos. Does it have a proper name and are they described anywhere?

Robert...the tensioning slipper is present and correct. Or was, last time I went in there. But it reminds me. About 10 years ago I bought a new .375x.225 cam Renolds cam chain. When I tried to fit it, I found it was bar tight and would not go on. It's still in its box, and I just checked...it is the 'correct' cam chain (not the lighter magneto chain). I have no idea why it will not fit. I kept the old one. Can't feel any wear in any case. A mystery...

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A couple of years ago I fitted a Thorspark electronic system to my 1960 Slimline 99. I'm pretty sure that the instructions were to leave the auto advance/retard as is, (not to lock it). Since fitting the Thorspark the beast has always booted up after two or three kicks and runs very smoothly with no apparent problems.

As for the debate on lock wire versus welding

To my mind lock wire would not be my preferred option just in case it comes loose or falls off and gets mashed up in the mechanicals etc.

 Although welding is not a recommendation either, but, a careful dab or two of MIG or TIG wire will be sufficient to hold the arms in the chosen (open or closed) position without causing too much heat damage/distortion as you would get with stick welding or oxy-gas welding / brazing and if done carefully can be undone. 

Provided the welds are just MIG or TIG spot welds they can be filed off with jewellers files, patience, a steady hand and, the surfaces and edges dressed up with little or no damage. If memory serves it took less than an hour to un-weld and pretty up an A/R off my mates bike and with some new springs an a little lubrication has worked perfectly well since then. Don't be tempted to use an angle grinder etc for obvious reasons.

Robert...the tensioning slipper is present and correct. Or was, last time I went in there. But it reminds me. About 10 years ago I bought a new .375x.225 cam Renolds cam chain. When I tried to fit it, I found it was bar tight and would not go on. It's still in its box, and I just checked...it is the 'correct' cam chain (not the lighter magneto chain). I have no idea why it will not fit. I kept the old one. Can't feel any wear in any case. A mystery...

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Hi David, I did not think anything missing ,but the chain looks  droopy on the bottom run. I've not done it myself (done plenty of other silly stuff) but I think its possible to fit the tensioner plates incorrectly, which may restrict the tensioner adjustment , a reason why the new chain won't fit?. Like you I have a spare new chain ,but the grapevine said the quality was suspect ,so the old one went back in , its past 60years old now ,think I should take a look!.I intend to do some fine tuning and set the cam timing to the best figures ,plus check the ignition is the same both sides. Like John I bought a thorspark type points replacement,never got it to work, think the 2MC confuses it. Edit,checking the "bible" the chain adjuster has 2 clamping plates ,,thin plate on first long end down,thick plate last,long end up!,  I know they will go on wrongly ,worth a check next time you are in there.

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The cut away timing case is not in place, Robert. I'm pretty sure that's why it looks a little slack. Next time I go in there, I need to Loctite that shaft...it spins freely which it should not do. One problem that causes is that it's all too easy to lose the steel washer behind the gear....

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I found mine to be loose in 1994 , too broke to buy Locktite  ,put it back loose. No problem since then. But I will use locktite  this time.   

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The Intermediate Gear Spindle should be fitted with with its midway oil feed hole facing downwards. You can just about make this out in the attached photo. This position is very important as oil from inside the crankcase feeds through the end to this hole and the lubes the Intermediate gear/pinion.

If this spindle is very loose it will almost certainly turn when the engine is running. Threadlock goo is one solution. Some people have tried plating the dogy end with Copper or Nickel to bulk it up a little.

The Timing Chest Chain lengths should be - Magneto / Distributor 42 links and Camshaft 38 links. A very dodgy trick for what appears to be an overtight chain is to first give it a good cooking and then fit it. This thins any excessive internal grease and also expands the chain. Mount it while still hot on the sprockets and turn thse a few times. Check again once cold. If still too tight once cold replace.

There are many questions being asked, these days, about the quality of British made chains. I have found that those for the rear do not last for very long despite regular spraying with grease or regular dunking in a tin of hot lubricant. Primary chains are no better. Checkout the photo of my primary chain after just 150 miles. That should not bend so much so soon.

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Back in the bad old days we ran primary chains till the rollers came off and the noise became a worry. Rear chains lasted till they broke.   Quite how you measure a cam chain for wear ?,not sure ,but the tensioner blade sheds steel shards till grooves are worn enough to allow the rollers to take the load,then it seems to go on for ever. My magnets run clean now .

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That's an interesting observation...I wonder how many Dommie engines meet a premature end due to the steel shards falling off a newly replaced chain tensioner?

 

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