The Lambretta mag housing is that round and odd-shaped piece of aluminium on the side of the engine; it may not sound important, but it carries out some vital tasks.
In some respects the design could have been better and in places it could certainly have been stronger, but as long as it’s well maintained it does the job it was intended for perfectly well.
What does it do?
The main purpose of the mag housing is to support the left side of the crankshaft by means of a central bearing. It also houses the stator plate and flywheel which creates the electrical power for the ignition and lights (the magneto, hence ‘mag’ housing). Its third use is as part of the engine’s cooling system. The flywheel and head cowlings are bolted to it, creating the path needed by the cool air blown by the flywheel’s fan to flow over the cylinder. This keeps it at the correct temperature and stops the piston from seizing due to overheating.
Bearing overhaul
The biggest service job on the mag housing is the bearing overhaul and requires the correct tools
