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MRF American Bosch Magneto

 The MRF is a later development that resembles the previous MJB in outward appearance but packs a wallop as big ot bigger than the big bad MJA series.  It uses the same cap,impulse and housing as the MJB and a simplified breaker mechanism as well as a different condenser. We are actively gathering more information to help keep yours in top form.  Here is a description from a 1963 catalog.




These are survivors. This one is still on the job with all original parts except needing to be relubed and a paint job.





The entire breaker assembly may easily be removed with two screws giving easy access to the condenser.  The coil and condenser connections are fastened by the breaker lever spring screw. If your ignition wrenches do not fit the lock nut on this screw recall that it is a standard 8-32  thread but for some odd reason the distance across the flats on the hex nut is 5MM.  The rotor shaft is supported by a large ball bearing unlike the MJB which uses a sleeve bearing.  These are excellent hot reliable mags and with proper care should be immortal.