Rebuilding the Jawa Speedway magneto ignition system

This bike is so simple there is no battery, just a magneto to produce spark. The issue is this one has seen better days.

4w ago
1.5K

The carburetor overhaul and oil pump cleaning were a breeze. Was hopeful that that magneto would be a piece of cake too. Wrong.

Have no idea how, but at some point some water looks like it go inside of the housing and ate the points. The spring literally had disintegrated.

Plan was to strip the whole assembly down anyway, so onward to see how bad the damage is.

The beauty of magnetos is that they are very simple and produce a great spark. A coil is rotates inside of a magnetic field. This rotation creates a charge. The charge is converted to spark when it is released by the points through the plug.

Things actually looked worse then they really were. Sure there was some rust and things that needed to be cleaned, but it was nothing that could not be corrected. Some elbow grease and brushing make quick work of things.

Replaced the points, and condenser with new parts.

What I am learning is that there is a thriving speedway community. Many people enjoying running, racing and collecting these interesting machines. As such there is decent demand for spare parts to keep them going. It also did not hurt that the same basic engine design was produced for decades, so there are many spares out on the used market.

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Spun the magneto on the bench with my cordless drill. Beautiful blue spark. Should have no trouble igniting the fuel for the engine.

Next on the list is to properly time the ignition to the motor, confirm the oil pump is pumping oil as it should, and button everything back up. I have a jug of VP racing's finest M1 fuel waiting to go. Should not be long until it is time to fire this monster up.

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