Navigation

You are here: Home / Messages / Heavy Twins / Re: Magneto Auto Advance!

Re: Magneto Auto Advance!

Up to Heavy Twins

Re: Magneto Auto Advance!

Posted by kevin_wood at July 10. 2017

I'm having trouble with the auto advance not retarding it's self properly. I spent all day fiddling with it yesterday. New chain nice and slack, fitted new springs etc. Moves free enough?

 

Only rhin hind I can think, the springs are slack/ish at rest/retard. A little tension would be nice. Could this just be poor quality springs?

The unit has been welded shut at some stage and opened back up!

 

Has anyone had a similar experience?

 

Would it it be worth putting the mag to manual and what would I need to do it? Slip ring, back points housing, cable and leaver?

 

Driving me mental! New units are made of rocking horse, by all accounts!

 

Shes a good mag. Had to bits and done the seal and checked the bearings and repacked with grease last year! Works well when stinking hot too, and that's what matters! Just get the timing on side and we are winning!

 

Locking at full advance might be an idea at the minute!

 

 

Kevin

Re: Magneto Auto Advance!

Posted by David Cooper at July 13. 2017

Kevin - nobody else has picked this up so I'll have a go...

The springs should have some tension at rest - or else there's no way it can retard.  I've never tested mine but it shouldn't reach full advance until roughly 3000rpm - maybe it could be mounted on a suitable electric drill and flash photographed?  Phone flash would be no use to freeze action but 'proper' camera flash is fast enough.

My suspicion is the springs.  If everything is free to move, there's nothing else to go wrong.  Unless of course something (like the weights!) is missing.

Can you post a photo - are do you have others and know exactly that it is all there?

It isn't one for the opposite rotation, is it?  I have a spare unit but it 'advances' the wrong way for a Norton!

If you lock at full advance you'll break your Achilles tendon...seen that happen once...

Re: Magneto Auto Advance!

Posted by les_howard at July 14. 2017

OOPS wrong one shown...Les

Re: Magneto Auto Advance!

Posted by David Cooper at July 14. 2017

Funny - looks totally different from mine...

 

Re: Magneto Auto Advance!

Posted by John Sunderland at July 14. 2017

Kevin: You mention that your auto-advance had been welded closed and then opened. It could be that welding has caused some distortion that is causing the problem. Just a possibility as the metal isn't that thick and the tolerances are quite small so depending on the type of welding, (gas or electric) the heat could have caused some distortion

John 

Re: Magneto Auto Advance!

Posted by anna jeannette Dixon at July 16. 2017

Hello On a Norton twin the Magneto should never get that hot  only warm you should be able to put your hand on the mag body after a long run and still not  be hot so it will burn you  having said this I had both my ATDs centre bolts come out  went they should not have  the bob weights should move freely and spring tension should come in  about half way to fully open the ATD is set in fully retard  when the engine is stopped  so when the engine is running it then opens with the rpm  as you may know  so if it's not opening then something is catching somewhere  so you may need a set of needle files to file off any obstruction there may be in there  or some how the pivot pins that hold the bob weights in place  have come distorted  this may be the cause of your problem I do hope you find this problem out or look out for another ATD in good condition    yours       anna j   

Re: Magneto Auto Advance!

Posted by kevin_wood at July 16. 2017

Hi there and thanks for all your responses.

 

The stinking hot hot mag is a fagure of speech. It means up to proper road running temp, 10 mins riding minimum. I mentioned this as it would rule out condenser and condensation problems.

 

I have been lucky enough to win one on eBay this evening. The whole thing possibly being distorted from it being welded Shut and re opened seems a sound idea!

 

i will wait and see what the one is like that arrives!

 

Incidently, I rebuilt my Dynamo on the Velocette today! That was a rewarding job! Easy too!

 

 

Thanks

 

Kevin

Re: Magneto Auto Advance!

Posted by jim_hill at July 17. 2017

Previously kevin_wood wrote:

I'm having trouble with the auto advance not retarding it's self properly. I spent all day fiddling with it yesterday. New chain nice and slack, fitted new springs etc. Moves free enough?

 

Only rhin hind I can think, the springs are slack/ish at rest/retard. A little tension would be nice. Could this just be poor quality springs?

The unit has been welded shut at some stage and opened back up!

 

Has anyone had a similar experience?

 

Would it it be worth putting the mag to manual and what would I need to do it? Slip ring, back points housing, cable and leaver?

 

Driving me mental! New units are made of rocking horse, by all accounts!

 

Shes a good mag. Had to bits and done the seal and checked the bearings and repacked with grease last year! Works well when stinking hot too, and that's what matters! Just get the timing on side and we are winning!

 

Locking at full advance might be an idea at the minute!

 

 

Kevin

Hi Kevin, I wrote about this problem some time ago on this forum, before you take the adv/ret device of just check one thing, with the timing cover off and the device not returned to full retard position, ease the engine over on the kickstart and see if that brings the full retard position back, I had a similar problem with my dommi some time ago and I gave it some thought, the design of the a/r unit is such that what you are seeing is the springs of the a/r device are trying to drive the engine forward !, not possible, but when the engine is rotated as in trying to start on the kickstart,the device will return to retard before the mag turns, so there is not a problem, worth a try you think,post the result please be tore you clear off on your ride ,

Regards Jim Hill

Re: Magneto Auto Advance!

Posted by jim_hill at July 18. 2017

Previously David Cooper wrote:

Kevin - nobody else has picked this up so I'll have a go...

The springs should have some tension at rest - or else there's no way it can retard.  I've never tested mine but it shouldn't reach full advance until roughly 3000rpm - maybe it could be mounted on a suitable electric drill and flash photographed?  Phone flash would be no use to freeze action but 'proper' camera flash is fast enough.

My suspicion is the springs.  If everything is free to move, there's nothing else to go wrong.  Unless of course something (like the weights!) is missing.

Can you post a photo - are do you have others and know exactly that it is all there?

It isn't one for the opposite rotation, is it?  I have a spare unit but it 'advances' the wrong way for a Norton!

If you lock at full advance you'll break your Achilles tendon...seen that happen once...


David , see my comment at the end of this thread,as long as the springs are able to control the bobweights the a/r device will revert to retarded position.

Re: Magneto Auto Advance!

Posted by kevin_wood at July 18. 2017

Thanks lads!

 

I got one off ebay that has never been welded and a couple of different sets of springs from two different suppliers.

 

Will see see how we get on at the weekend and will report back.

 

Kevin

Powered by Ploneboard
Upcoming Events
Brittania Rally - Denmark Aug 18, 2017 - Aug 20, 2017 — Jolly Roger Mc, Nørre Langgade, 8840 Rødkærsbro, Denmark
2017 International Rally Aug 24, 2017 - Aug 28, 2017 — Open Huis, Ieperstraat 157 - 8840 Staden, Belgium
2017 MGP Reunion Aug 29, 2017 03:00 PM - 06:00 PM — The Shore Hotel, Old Laxey Hill Laxey. Isle of Man IM4 7DA
Tay Valley Branch Camping Weekend - Town Yetholm Sep 08, 2017 - Sep 10, 2017
CRMC Track Parade - Anglesey Coastal Sep 09, 2017 - Sep 10, 2017 — A55, Ty Croes, Gwynedd LL63 5TF
Upcoming events…
This is Brio Diazo Plone Theme