Boyer question

bodlan

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I was just reading that when using a Pazon or electronic BTH mag you should modify or weld up the ATD to stop it moving. Whilst resetting the timing of the Boyer fitted to my Comet I notice that this has not been done. With the Boyer rotor in place I can easily move it with back and forth against the springs.
I'm puzzled now because this has been on the bike since before I got it and has never given any problems, as far as I know! Of course I may have been getting inferior performance all the time and not knowing any better since I have nothing to compare it with. I don't know anyone else with a Comet with a standard ignition set up I could compare performance against.
Any other Boyer users like to comment?
 

b'knighted

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How old is the Boyer system? Does it have an electronic advance inbuilt or a "distributor shaft" with bob weights?
 

Robert Watson

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I used a boyer for some time and found that it was likely off a vert twin and only had about 20 deg of adv built in, not enough that one could both have enough advance to run the engine propery or enough retard to be able to start it without a major kickback, so perhaps the previous owners left the ATD and limited its movement, to make up the difference. PLUS I found Boyers use a lot of power to operate.
 

BigEd

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VOC Forum Moderator
The Spares Co list a fixed gear PR22/BTH/DRIVE kit for use with the electronic BTH magneto. In the fitting instructions for the BTH it suggests that as an alternative you can use the original mechanical ATD if it is "fixed" with a spot of weld to stop it advancing. (Assuming that the tufnol gear is in good condition.) As the BTH and Pazon have a built in electronic advance you will presumably get two lots of advance if the ATD wasn't "fixed". I don't recall if Boyer made a unit without electronic advance although it is or at least was possible to specify no electronic advance for the BTH.
 

bodlan

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I have the previous owners receipt from 1998. It was fitted by the Acton M/C Centre, 7 The Vale, London, W3. They don't appear to be in business any longer. A friend has suggested that only Kirby Rowbotham was supplying Boyer kits for Vincent's back then. It is a Micro Mk III which does have an inbuilt advance but what it is I don't know. I'll have to get in touch with Boyer and find out. The rotor and stator plate are mounted in a very nicely made housing where the mag would have sat under the front cowl.
I have just been looking at Paul Goff's site and see that the stator plate of the Pazon is the same diameter as the Boyer one so I may switch to Pazon as it claims to work as low as 8V whereas the Boyer seems to require at least 12V at all times. They also advertise a specific Vincent curve. Hopefully the rotor dimensions are similar to the Boyer one. Either way it seems that I should get the ATD spot welded to stop the double advance taking place.

Among the many posts I have read on here recently I recall someone saying that they got from Boyer an ignition box specifically with a Vincent advance curve even though Boyer do not advertise Vincent among it bespoke kits. Can any one remember who that was? Be interesting to find out how easy that was to get and if successful.
 

ClassicBiker

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I fitted a Boyer as supplied by Kirby Rowbotham to my comet when I first got it. Not sure right now who I purchased it from right now. It was advertised as having having a Vincent specific curve, of that I'm sure.
Steven
 
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