Classic cars forum & vehicle restoration.

[Rootes75]

My youngest has grown a real interest in Stationary Engines over the last couple of years, he is only 5.

When my Grandparents died a few years back I rescued a few Stationary Engines and amongst them was a 5hp JAP, quite a nice and unusual engine. I recently dragged it out and started to take a look at its operation, it turns over well with good compression but the mag produces no spark that I can see.

Is there a simple way of checking the Magneto is working correctly?
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Various Rootes Vehicles.

[peter scott]

Strangely enough my brother in law just asked me the same question at the weekend (re a British Seagull outboard).

Separate the points with a piece of paper and connect one side of a 6 volt battery to the fixed side of the points then give a quick touch of the other battery terminal to the moving point. You should get a health spark at the plug if the coil is OK. (Polarity is unimportant.)

This is quite likely because the common failure of magnetos is loss of magnetism. In the outboard the magnet forms part of the circumference of the flywheel and couples with pole pieces that pass through the coil.

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Kenham]

I am guessing that if fitted to a 5 hp JAP it is a Wico A type magneto. All you can really do is give it a good clean , take out the points and clean properly to remove pitting put it back together and try it. Most old magneto's usually work when cold ,problems arise when hot with dodgy coils and condensers breaking down. One thing to make sure of is the piece of insulation between the points spring and the mag body is fitted if it is an A type. This is only a quick way to see if it does produce a spark of sorts of course.

[Peter_L]

One problem I have had on much used grass cutting equipment is a build up of rust on the armature and fixed section. An air gap, although very small is required in order for the system to create an induction in the coil.

Put a meter across the coil and spin the mag, if there is no voltage rise, check coil continuity and the air gap. Both present and no spark would point to either the condenser/capacitor, wiring, points problem or Plug.

[Rootes75]

It is a Wico mag, next time I am at the shed I am going to remove it and give it a good clean.
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Various Rootes Vehicles.