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• DU1,DU2,DU4..Ad nauseum Bosch Catalog 50

DU1,DU2,DU4..Ad nauseum Bosch Catalog 50

Here is  catalog 50 from American Bosch with descriptions, configurations and parts lists for the very popular DU series magnetos. These were widely used and recognized by their two horseshoe magnets and flat red hard rubber distributor disk. They were well made and many survive today in working order despite nearly a century of abuse and neglect.  As always, recall that they were made in Massachusetts, yet were assembled with standard metric fasteners. The spark plug terminals on the distributor disk and the two hex bolts fastening the disk to the housing look a lot like the typical 10-32, but are actually 5MMx.8 threads.The pitch is similar but the outside diameter is larger.  One can usually take a sharp 5MMx.8 tap and run it into a 10-32 knurled nut or brass inserted plastic knob to fit the original spark plug terminals. There is a lot of info in this catalog to help keep your mag alive and well. The DU.. and ZR.. series were replaced by the new and improved MJ.. series.

Beware of sticky goo. This is typical if the armature does not turn freely or at all. Get it hot to about 200 degrees and it should slide apart.If the insulating varnish turns into sticky goo it probably will not stay put and it is rewind time.