Magneto repair required

[Guest]

Afternoon all,

 

My magneto off the J2 is not creating a spark. Does anyone know of a good repairer, preferably near Yorkshire.

 

Thanks

 

Paul

[Tony Brooks]

Not a direct answer but I think magnetos have a condenser, for the same reason as coil ignition, and contact points. If it is easily replaceable I would suggest trying a new condenser and cleaning and gapping the points if you have not done those already.

 

Over to the Kevin experts

[Guest]

Hi Tony,

 

Cleaned up the points and re-gapped them. Mr Goble determined it was dead.

 

Just got the engine back together after replacing the heads too!!!

[BEngo]

I have used Magneto Repairs, Merlins Mill, Stroud and had good service.  I am not sure that they are currently accepting work though. 

If Dick G doesn't know someone I would post a query on one of the Stationary Engine forums, or the Internal Fire forum, giving details of the magneto as not all repairs can or will tackle anything.

 

Or pick up a copy of either Stationary Engine magazine or one of the tractor magazines at WH Smith.  There are always magneto repairs advertised.

 

N

Edited December 6, 2021 by BEngo

[Tony Brooks]

A shorted condenser would make it dead but I am no expert. The only bigger engines I have dealt with that had magnetos were some Aston Martin and they has a pair of them. Never had to take them apart though.

 

The only things left would be a loss of  magmatism or a faulty coil and I think those would need someone who knew magnetos.  I was going to suggest the magazines  BEngo mentioned

 

 

[BEngo]

Most magnetos pack up either because the magnetism has faded and  won't make a big enough spark, or because the HT coil has gone open circuit. Modern coils are more reliable because the impregnation resin is better and voids are less common.  The very fine HT coil wire is still under a lot of mechanical stress every time there is a spark though.

The HT coil can be continuity checked with a multi meter. Weak magnets can still give a spark if the plug cap is reduced radically. Some Lucas magnetos are particularly prone to this, by unintentional design.

Condensers usually fail open circuit, which results in a low energy spark and burning of the points.

 

When you do get it fixed, ensure the impulse drive unit is working properly.  It makes a big difference.

 

N

Edited December 6, 2021 by BEngo

[Tacet]

The shellac insulation on the armature windings deteriorates - and when the magneto is warm, is more inclined to short thus making a poor spark.  There comes a time when the engine starts from cold - but frustratingly  won't readily restart from hot.

[MtB]

15 minutes ago, Tacet said:

The shellac insulation on the armature windings deteriorates - and when the magneto is warm, is more inclined to short thus making a poor spark.  There comes a time when the engine starts from cold - but frustratingly  won't readily restart from hot.

 

I guess you are talking about hand-start-only Kelvins. On mine, both will start straight to diesel if I press the starter button, if they are any warmer than stone cold. 

Edited December 6, 2021 by MtB
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[frangar]

Here’s an ad from stationary engine magazine that might help. It’s from the Dec 2021 issue but I’m sure there used to be more…I will have look through some back issues. 
 

[dave moore]

They were the company I had in mind to refurbish the magneto on our J3. I think they quoted around £500 and needed to know the rotational direction. Having fitted thermostarts, I never got round to it.....

[john.k]

What magneto is it......some,like the SR series Lucas mags are cheap to fix.