B.T.H PBM1 Mag-Dyno (Early Series ‘A’ Singles)

A Nut

Well Known and Active Forum User
VOC Member
If you are not a stickler for originality you can use a pre war Lucas MO1 magneto (ring cam type not the later face cam type) Machine away the drive train casting, machine 10mm off the base to bring the spindle height down to 35mm and then drive the dynamo with a pair of toothed pulleys and a Megadyne belt. I have an original magneto for my Comet rewound and sitting on the shelf but prefer the Lucas magneto as I get a better spark. I should add that I have gone one stage further and used a post war MO1 body (with Nifal cast in magnets) as this is better than the plate magnets in the early Lucas, Miller or the BTH instruments. My rewound Miller dynamo gives ample charge but at some stage I will try using a 50watt Miller in place of the 36watt one. At this point I think that my fellow Mid Glos section member and Series A owner, Stan Chappell is having a heart attack after reading of my modifications! Brian Werrett.
 

Georgehrd

Forum User
Non-VOC Member
If you are not a stickler for originality you can use a pre war Lucas MO1 magneto (ring cam type not the later face cam type) Machine away the drive train casting, machine 10mm off the base to bring the spindle height down to 35mm and then drive the dynamo with a pair of toothed pulleys and a Megadyne belt. I have an original magneto for my Comet rewound and sitting on the shelf but prefer the Lucas magneto as I get a better spark. I should add that I have gone one stage further and used a post war MO1 body (with Nifal cast in magnets) as this is better than the plate magnets in the early Lucas, Miller or the BTH instruments. My rewound Miller dynamo gives ample charge but at some stage I will try using a 50watt Miller in place of the 36watt one. At this point I think that my fellow Mid Glos section member and Series A owner, Stan Chappell is having a heart attack after reading of my modifications! Brian Werrett.
Haha that’s some modifications sadly I am a 100% original kind of guy if it’s not original it annoys me that much I spend days after days years after years to find 1 part that is original to change it over and some of the parts no one would know but I do and that’s enough to bother me I don’t mind putting something on if that’s all that’s available but I make sure I eventually find the correct part to replace it as soon as I can it gets expensive I even purchased a vintage Honda 125 for a work bike said I was doing nothing to it until I notticed un original parts on it now I have replaced that much it’s got to stay in my collection motorbikes is a dangerous but fun game money wise haha thanks for the message mate kind regards George
 

delboy

Well Known and Active Forum User
VOC Member
Unless you mill off the base of a "powerdynamo" yourself, you're out of luck as they no longer supply them with the 35mm spindle height of a Series "A".
-Unless they've changed their minds while I wasn't looking!?
regards,
Delboy.
 
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