Ariel

[fifer]

The springs keep the advance /retard unit in the closed { fully retarded } position when stationary .
As the engine starts , the weights fly out by centrifugal force relevant to the engine speed , advancing the ignition till the unit butts against the internal stops .
The engine is now fully advanced and at its optimum power position in relation to where the spark is produced Before Top Dead Centre .
As the points heal wears the gap closes and the ignition get progressivly retarded requiring you to reset the gap to restore full power .
Click the following link from one of the Ariel links below to view the advance /retard unit
http://i274.photobucket.com/albums/jj254/cosmikdebriis/C11gEngine%20Dismantle/4eInsertTool.jpg

If you think about it , what happened if your ignition was too far advanced { timing out }, and you kick started it .
Yep , bruised shins .
The early magnetos had an advance / retard lever on them because the timing was set at the optimum fully advance position .
When you pulled the handlebar advance / retard lever it retarded the ignition so that you had less chance of getting the kickback .
You then moved the lever back to the closed position and the engine was fully advanced .
The later magnetos had an automatic advance retard { same principle as fitted to reliant distributors }
However , lots of folk could not set up the unit at the correct ignition point and many changed back to the old manual magnetos .
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Found the following Ariel info which might be useful { It also shows the unit with springs attached }

http://www.draganfly.co.uk/data/pdf/ListLH2.pdf


and
http://bsac10c11c12.co.uk/smf/index.php?topic=3782.0;prev_next=next#new
and
http://forum.arielownersmcc.co.uk/viewtopic.php?f=40&t=506


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[blair]

hi guys and thanks for all the input, i kinda understand what the unit is suppose to do .

Fifer , the unit on the link looks different to the one fitted to mine and the dragan fly diagrams dont give enough detail really . but the link from the ariel owners club ( Paul linden's build ) is the same as mine in fact he has been helping me with some other questions i have as my build is on that site also . his doesnt look like it has springs or even location for them to be attached too and mines looks identicle to his .

spanners and old newbie may be onto something though and i think the best thing to do is grind the mashed thread ends and take the unit apart to see how it works 

cheers

[fifer]

Nearly all older engines have a spring loaded advance /retard mechanism so that you can get the variations in optimum timing setting .
However , it was common practice to weld or screw the advance /retard unit so that you had fixed timing which meant that the timing stayed at full advance .
Broken ankles were a by product unless you bump started .
Looks like your one might be the same ?
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[morrag]

Oops, excuse the Freudian slip! of course the points are held in the fully retarded position at rest, hence the need for springs, advancing once the engine runs above tick-over speed. I would disagree with the assumption that,"... many folks could not set up.." indeed manual and auto Magnetos were common through out my formative years, the manual being preferred in more sporting situation like the Velocette's I ran in that period, the Auto for your average "cooking" motor!. A "Colt" wouldn't do you too much damage! but a Venom Clubmans broke my kneecap once,a long time ago, when the bugger kicked back, ho hum, happy days! and I still limp .Morrag

[fifer]

I had to fix many a timing fault on BSA and Triumph bikes fitted with automatic advance /retard due to the owners setting the timing wrong .
This caused either lack of power due to being retarded too much or kick back due to being advanced too much.
The old boys who knew a wee bit but not enough to set the timing spot on used the cable operated manual advance magneto and set the lever in the position the bike ran best .   
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[morrag]

I'm one of those "old boys" Fifer, and my own experience marks that as a load of rubbish, frankly. The guys I grew up with on motorcycles were generally very capable in maintaining, what was usually their only mode of transport,for work, pleasure, and everything else come to that! and anyway it was a matter of pride back then that you carried out your own maintenance on your machine. Granted they were fairly simple pieces of equipment compared to today's electronically, multi-cylinder, offerings, but never the less, they generally required a little more than "a wee bit" of know how! so maybe your experiences were just "unfortunate" in that regard..................

[Manky Monkey]

Gentlemen! No fisticuffs before the ladies have retired to the drawing room & the port's been served, please.

[blair]

port ...... dont mind if i do 

[Manky Monkey]

Jaffa Cake?

[blair]

ok been out and had a look and well there wa smore crud than i realised so whent at it with a wire brush and indeed i found what looks like mounting points for springs . and i cant remember who said they may have been fitted on the rear of the unit but yes you were correct , now do i lock it up like it was or find springs and refit them 

Ariel

Ariel

Ariel

so thanks again to everyone for the advice and now its time for a port and kitkat 

[fifer]

I'm one of those "old boys" Fifer, and my own experience marks that as a load of rubbish, frankly. The guys I grew up with on motorcycles were generally very capable in maintaining, what was usually their only mode of transport,for work, pleasure, and everything else come to that! and anyway it was a matter of pride back then that you carried out your own maintenance on your machine. Granted they were fairly simple pieces of equipment compared to today's electronically, multi-cylinder, offerings, but never the less, they generally required a little more than "a wee bit" of know how! so maybe your experiences were just "unfortunate" in that regard..................

Now that I think on it , I probably only ever met mechanical dumbos , otherwise why would they let a 15 year old fix their bikes  

Morrag , I apologise if I worded my post so that it came across differently .
That was not My intentions .
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[Manky Monkey]

"Port and kitkat"
-heathen!

[morrag]

You guys should know that the Port is always served to the left, preferably accompanied by a nice piece of Stillton and a few Water biscuits! so please, let us not see our standads erode!! , kit kat indeed....Morrag

[spanners]

port and stilton  to the left , ----------------------------------jaffa,s and coke,,, -------------to the right 

[triker_Chewie]

bundaburg down the middle