Saturday, May 5, 2012


Trying not to be too down about not being able to pick up tools I have been doing some information gathering.

The stash of parts I have has four magnetos in stock.  Two BTH dirt track mags, a SEM from Sweden and a PAL which I believe is ESO from Czechoslovakia.   The PAL is interesting but has been promised on a parts trade o a friend in Australia who has an early ESO that needs spark.

That leaves the BTH and the SEM mags.  The BTH as the usual unit used with the JAP engines.  And both of these come with manual spark advance.  What little I understand of the SEM is that it is used for speedway and ice racing and has a reputation for reliability and the traditional Swede quality.

The problem is I have no idea if any of these four actually spark.  Or if they do spark is it good enough to run the JAP.  So off to surf the great information sea I went.  I found little or no help on the SEM magneto.  I may have just been not digging enough or used the wrong search strings.

I did find some reasonable info for the BTH.  These guys Bright Spark Magnetos,, have an interesting web site and are trying to address some of the problems with old magnetos.  Very interesting bunch of information regarding know problems and solutions using new materials and technology.

I also found this site Racing Vincent UK,  This is a very commercial site offering restoration parts for Norton and Vincent.  But what I found interesting and maybe useful is they offer a range of bits for BTH magnetos in the catalog.  Go here for the list of BTH bits.

I haven’t made an inquiry of these guys but it does seem they may be in business and could provide those hard to get bits for a BTH refurb.  You know like the gaskets and screws and stuff along with new bearing and such.  There is a small interesting note of the parts page.  They indicate that the BTH Dirt Track mag and the TT mag were the same mag; just a different name plate.

So all in all, with some more surfing under my belt, I’m pretty much decided on using the traditional BTH mag for spark.  Now to try and determine if either one of the KD-1 mags spark and what I will need for bits to get them fit to bolt up to the JAP.

So anybody have something to trade for a SEM speedway magneto?

`                                          SEM Magneto

                                         BTH KD-1 Race Magnetos.  These two appear to be 
                                         of dfferent vintage magnetos.  Just need to wait and try
                                         a test and see if either will work.

In the meantime if anybody has better information to share or has a great easy way to test a magneto please let me know.

1 comment:

  1. That SEM might aswell come from some kind of smaller outboard engine...