Petter A1 magneto

Hi, I am re building an old A1, and fitting the magneto when I check the spark there is none. I am not sure how the check the coil, but have removed it and measured the resiatance. Between the centre contact (HT connection) and earth I have c5Kohm, but the other connection is open, either to earth or the HT contact. Does this mean the coil is faulty? One other thing, from time to time, if I accidentally spin the spindle and touch the HT contact I get a shock, but when I attempt to repeat I can not always get a shock?

Looking at one of your videos on timing an A1, it shows that there should be a distinct "click" when turning the mag, which denotes when it should spark. I have no such click

If I need a new coil, where could I source one?

Your magneto should have a flick device that through a lever, driven by centrifugal force stops the magneto rotating and a spring is also wound up until a trip lets the magneto spin at high speed to produce an enhanced spark. Once the engine is running the trip mechanism stops and the magneto is directly driven by the engine.

The trip could be siezed. Sounds like a connection issue or condenser on it last legs.
Andrew

Thanks for your replies, I have attempted to investigate, but not sure of best way to strip, so I was wondering if anyone has experience of getting into this device?

I can see nuts under the weights, but it looks like the pins to remove the weights are pined over, so not simple to remove, and looking at the drawings (attached), may not be necessary. It looks like the nuts are holding the gear in place to item 18, but it is item 18 I think I need to remove. It looks like item 18 should simply slide off item 17, and item 15 should pull away from item 14. I do not want to apply too much force to remove without some reassurance that there are no un seen fixings

Can anyone provide guidance on how to remove this assembly to gain access to check the trip

Thank you for your help

Michael,
The items you refer to are part of the engine, the parts we are refering to are the lump sticking out of the end out of the magneto.

Mary alice

Let's wind back a bit. You have a Wico A mag on a Petter A1, does that Wico have the gear attached or does it have the cush drive like your photo? If it has the gear attached then you need to remove the gear first....

Hi yes, it has a gear attached, not a great image, but the only one I have available at the moment is attached. Do I need to file the pineing off so I can take the weight pins out, so I can gain access to the nuts below? A previous post suggested I need to check the the trip has not sized, so am trying at get at that, but not sure if there is a simpler way to get at it?

Thanks for your help

Not sure why images are not attaching, so trying again!

Right, if that has the proper Petter pins you should just need to nip one end as they aren't riveted but opened slightly on one end similar to a split pin, if not then you will have to file/grind the pins, under the weights you should see a pair of bolts or nuts, undo them and the gear will come off and allow you better access to the impulse coupling, then undo the center nut and that impulse should come off, be careful as it has a spring inside and if that goes ping you will have bits all over the shed!

Thanks..... I will give that a try tomorrow, wanted to make sure the weights needed to come off before I tried, as the pins are significantly pined over and look like a pain to remove, maybe they have been removed before?

Love your Bart Avatar by the way!

Well you learn something new every day, all the Petter A types I had had the slotted disc not the set up shown.

Maryalice

[quote="maryalice"]Well you learn something new every day, all the Petter A types I had had the slotted disc not the set up shown.

Maryalice[/quote]

Was the later ones that had the cush drive, Zenith carb and pressed steel exhaust, earlier A1 had the direct drive mag, Solex carb and cast pig snout exhaust (Normally)

If you was to collect real engines rather than the Dursley Dross you love so much you'd know.....

Appletop wrote:

maryalice wrote:Well you learn something new every day, all the Petter A types I had had the slotted disc not the set up shown.

Maryalice

Was the later ones that had the cush drive, Zenith carb and pressed steel exhaust, earlier A1 had the direct drive mag, Solex carb and cast pig snout exhaust (Normally)

If you was to collect real engines rather than the Dursley Dross you love so much you'd know.....

I wont point out that your collection became part of the same group

Maryalice

[quote="maryalice"][quote="Appletop"][quote="maryalice"]Well you learn something new every day, all the Petter A types I had had the slotted disc not the set up shown.

Maryalice[/quote]

Was the later ones that had the cush drive, Zenith carb and pressed steel exhaust, earlier A1 had the direct drive mag, Solex carb and cast pig snout exhaust (Normally)

If you was to collect real engines rather than the Dursley Dross you love so much you'd know..... [/quote]

I wont point out that your collection became part of the same group

Maryalice[/quote]

Well, sort of, Petter got bought by Hawker-Siddeley in 1957ish and they ran as Petter until Hawker-Siddeley bought Lister in 1965ish and it was Siddeley who merged them.....