Airpne weak spark

[electrajohnt]

Trying to bring the 1948 Airone out of mothballs so I can sell it. About six years ago I had the magneto refurbished, I didn’t run it for long, but it did run, before I put the bike away in the garage. Always dry and kept covered. 

Trying to start it, I have a weak spark.

If I take the spark plug out and give it a could spin the spark is presentable. Put the a false plug in and connect the “proper” plug to the lead, earthing the plug  I see a much smaller spark. This I think, is caused by the compression preventing me getting decent momentum from the kick start. Even if I push the piston just past compression and give the kickstart a hefty shove the resultant spark is weak.

I have taken the plug cap off and soldered a eye type connector for the plug onto the plug lead in the hope the cap was not good, maybe a suppressor cap, I don’t know, but this made no difference.

I cleaned the ring the carbon pickup runs on.

All this not made any difference.

I suppose the next step is take the magneto off and send for another refurb.

Before I do that has anyone got a suggested option I can try.

JohnT

[John O Regan]

Hi All,

First of all make sure the points are absolutely clean and gapped correctly

Look at the points as you kick the engine over without the plug fitted 

If you see yellowish sparking at the points it indicates a bad condenser..

You can also measure the  coil HT winding resistance it should be in the region of 4 to 6 K ohms 

John 

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[Rick Yamane]

Close the gap on the spark plug and make sure you flood the carb with the tickler. While messing with my GTV someone mentioned “A weak spark likes a rich mixture”. I was afraid of fouling the plug by over tickling but I’ll be damned if it didn’t help. Closing the gap helps combat gas fouling by reducing the number of fuel molecules between the electrodes when it fires. An old trick I learned while racing 2T dirt bikes.

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[Gordon de la Mare]

Do make sure that you use a non-resistor spark plug gap.

This did fix a similar problem on one of my Falcones that did have a weak spark.

Cheers

Gordon

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[electrajohnt]

Hello John,

Thank you for your response.

I have a tester for ohms etc but don’t know how to test coil HT windings, would you mind describing how I do that. Does the magneto have to be stripped or can I do it in-situ.

Regarding the condenser, same as above. Also any idea where I can get a condenser if required.

Do you, or anyone else, know what the ignition timing should best full advance when measured on the periphery of the flywheel. The various Airone manuals on “This old tractor” seem to give conflicting dimensions.

[electrajohnt]

Thanks Rick, I will try that.

[electrajohnt]

Hello Gordo.

See my initial post. I was not sure about the plug cap, I do not know how to tell if it is a resistor type or not. So I took of and soldered a “eye” onto the end of the copper lead and used the nut on the end of the plug to hold it on place.

[Alan Scott]

Hello John, 

I don’t really have any more I could add to the advice you’ve already received but I am curious, you said your selling it? 

How much are you looking to get? Where is it located?

I was thinking of getting a 500cc but maybe a 250cc will do.

Alan

On Jun 22, 2023, at 3:07 PM, electrajohnt <johnm...@gmail.com> wrote:



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[Andrew Nahum]

My tecent Airone magneto problem was a poor internal connection and a tired capacitor. My magneto guy didn’t have a Marelli type to fit inside the magneto so attached a standard automotive one outside. Some people think it’s a shame but it’s a neat job and the bike works great. Got me back on the road in 2 days. And thanks to Mike Peavey for explaining how to get the magneto off, preserve the timing, and not lose any fiddly bits inside. 

On 22 Jun 2023, at 21:03, electrajohnt <johnm...@gmail.com> wrote:



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[Rick Yamane]

A bad condenser/capacitor usually manifests itself as creating a big fat spark but without amperage to push through the air/fuel mixture. It might allow the engine to start and run for a bit but as it warms up the condenser fails and the engine stops. You should run solid copper or aluminum wire and as said, no resistor cap. There really are only a few things to check if you are getting any spark at all. If the contact points are clean as well as wire connections the magnetism of the permanent magnets can and will drop off. Remagnatizing is  usually done at overhaul.

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[Roger Rowland]

On a Falcone the reading from plug cap to earth should be 5K ohms, as mentioned non resistant plug and cap helps. I spent a lot of time redesigning the wheel and made a better cap magneto end as I didn’t like the Biro spring for conducting the HT current. Only to find the coil wire is microscopic so a complete waste of time!! Personally I cut a hole and stick a degree disc with blue tack and set 6 BFTDC you can see advance with strobe. Checking from points wire to plug cap should then be ? I think 5k ohms slightly plus. From wire through primary coil to Earth from Earth through secondary coil to cap. A significant reduction then I would think the insulation has broken down ?
Am I right
Regards Roger England 🏴󠁧󠁢󠁥󠁮󠁧󠁿

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> On 22 Jun 2023, at 21:03, electrajohnt <johnm...@gmail.com> wrote:
>

[John O Regan]

Roger answered your questions before I got back to the site,

Set the meter to K ohms (20?) range if the meter does not have an auto range

A

Fitting the external condenser can get you out of  trouble or aid diagnosis, Any auto type condenser will work fine

John

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[Roger Rowland]

I’ve had the magneto apart a number of times, have found it generates a really strong spark. What I find quite odd is some of the design. Particularly the mounting/ alignment and ease ( or not) of adjusting the points. As a bike used extensively by the police etc you would think it would be simple. Well not for me and the spares ( points) seem to have an incorrect over tight spring it is a fiddle at best? The mag is robust the rotor bearings advance etc. My concern is the coil. An idea I’ve had is to mount the condenser outside the case the coil would slide out ( undoing the two grub screws) If so carrying a spare coil is not much of an issue. Anyone done this ? The condenser connected with Wago fittings ( German electrical connectors) perhaps a coil change could be done in 20mins?

           A thought anyway 

Regards Rog England 🏴󠁧󠁢󠁥󠁮󠁧󠁿 🤔

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On 23 Jun 2023, at 22:17, John O Regan <chate...@gmail.com> wrote:



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[Patrick Hughes]

Roger, do you mean condenser change in 20 mins? You will not do a coil change in 20 mins.

I have had some new points with an impossibly strong spring. I could not fit one set and tried another set from Guzzi Retro, these had a much better spring, still strong enough for the job mut much easier to fit. I think I got the duff ones from Ebay. I only buy from Guzzi Retro now.

Regards Patrick Hughes

Harmill Systems Ltd.

Sent from my Samsung Galaxy smartphone.

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From: 'Roger Rowland' via Guzzi Singles <guzzi-...@googlegroups.com>

Date: 23/06/2023 23:36 (GMT+00:00)

To: guzzi-...@googlegroups.com

Subject: Re: [guzzi-singles] Airpne weak spark

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[Roger Rowland]

Yes the coil, if the condenser is outside the brown insulation plate removed, disconnected wire ( Wago fitting). Undo two grub screws will the coil slide out ? Obviously front cover off 

       🤔Regards Rog 

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On 24 Jun 2023, at 08:14, Patrick Hughes <patrick...@harmill.co.uk> wrote:



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[electrajohnt]

It is sorted, there are a couple of manuals on This Old Tractor, they give conflicting peripheral dimensions on the flywheel.one says 40mm the other says 80mm. The 80mm at full advance is the correct one.

Thank you all for you help.

Regards

John Taylor.