Ariel Owners Motorcycle Club

Hi, all.

How did the factory set the ignition timing on a MO1L magneto? Surely not with a cigarette paper, surely?

Charlie

As per the applicable owner’s guide or Waller’s book or the Davison/Haycraft book.
A depth guage with an electronic timing buzzer combined with a vernier sprocket on the mag is the most accurate method now.

hi that is how i do the timing on mags my electronic box has got a light and buzzer and it uses a 9v battery to power it i find it very good there is one showing in the AOMCC owners guide how to time a mag

Timing is not too critical on Ariels, especially those with manual advance - retard where you can adjust the timing as you go along. The fag paper method is plenty accurate enough and has served me well for many years now.

Thanks for the replies, wonderful people!
I might try the buzzer method. Haycraft uses a fag paper and Waller and the Ariel Owner's Manual don't specify how to detect the points opening.
I was hoping someone had knowledge of how the factory timed the ignition.

You can check the timing by how it runs.Idle then advance fully and it should speed up but stagger. Retard and the motor slows and the note of the exhaust deepens and the pipe gets hotter. Run at full advance minus a bit. Start at retard plus about 1/4 to 1/3 of lever movement. Watch for kick back at the 1/3 position but the spark is better than at full retard. The usual advance should be about 35 degrees at full advance. Degrees are more accurate than piston BTDC. Nev

Factory probably used a fag paper.

Years ago I cobbled together an electronic indicator to compare fag paper and indicator.
I was very consistent with both, getting visually the exact same degree reading time after time.
The paper was a fraction of a degree retarded, as you would expect.
But my checks were on an engine with a BTH single mag that was on a work
bench, an M01, long dynamo, side of the road and some rain and I am probably not as accurate...................

I have acquired a BTH indicator, it's an ex RAF thing. But I got it as an empty box. I had to find the patent
to see how it worked, since I looked at the patent someone has written a web page about one with
pictures.

Thanks for the reply Rick. I have bought a buzzer device and will use it next time. Although if the factory used fag paper the timing information should be compatible with this method. I've never been confident about the consistency. Thankfully the timing is not absolutely critical in these machines.

Beware. Using any significant current to the centre screw can diminish the magnets effectiveness by demagnetising it. The armature acts as a keeper but if it flows current in the primary it becomes an electomagnet temporarily and it the polarity is wrong too bad for your magnet. It can be remagnetised but that's a lot of trouble. Nev