Misc: Ignition New BTH "magneto" heat tolerance?

CoreyL

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Do any forum members have data/anecdotes/experiences related to whether or not the new BTH "magnetos" are sensitive to heat? I went for a short ride on my single with the mag cover removed and noticed that the BTH was quite hot when I got home. Not surprising, I suppose, since it's bolted to the crankcase.

Is there any evidence that, over time, some of the electronic componentry inside the unit suffers as a result of the heat? I've seen photos of Vincents in road-going trim with their mag covers removed and I wondered if that was done to help keep things cooler.

Any thoughts/conclusions/theories would be welcome.
 

BigEd

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Do any forum members have data/anecdotes/experiences related to whether or not the new BTH "magnetos" are sensitive to heat? I went for a short ride on my single with the mag cover removed and noticed that the BTH was quite hot when I got home. Not surprising, I suppose, since it's bolted to the crankcase.

Is there any evidence that, over time, some of the electronic componentry inside the unit suffers as a result of the heat? I've seen photos of Vincents in road-going trim with their mag covers removed and I wondered if that was done to help keep things cooler.

Any thoughts/conclusions/theories would be welcome.
I've had a BT-H magneto on my Rapide since I built and used it with the mag cowl fitted. No problems during the 50,000 + miles I've completed and it has been used in all weathers, hot, cold,and also wet.
 

bmetcalf

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How many miles in Texas hot weather? The average highs in the summer in Corey's town are 93F!
 

Robert Watson

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I have run one on a post war twin to the NorCal rally in Weaverville some years ago. It was very hot for a few days as in well over 100F. Not a problem with the sparks.
 

ClassicBiker

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Corey,
Your post got me thinking as I have a BTH fitted to my Shadow that I bought used off of evil bay. The new BTHs are CDI units mounted externally. CDIs have been used for years on bikes made by other manufacturers and they are all mounted inside the engine covers. I suspect that they are therefore operating at temperatures that are slightly higher than the BTHs mounted on Vincents are. Looking at the coils that come with the BTHs and those that are advertised as replacements for various other makes, there does not appear to be much difference. This leads me to believe that the components inside the housing would not be to markedly different to what is in use on other machines. Having said that I wouldn't be surprised to find the internal components adapted from already existing production to reduce development cost. I think therefore the operating temps our BTHs are experiencing are within their capabilities. But all this is just conjecture on my part.
In fact Electrex World https://www.electrexworld.co.uk/ markets CDI components for BSA and Triumph singles. I have often wondered if I could take those components and adapt them to my Comet's primary without changing the appearance of the primary cover or make a suitable BTH like housing that would fit under the mag cover.
Steven
 

oexing

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You mostly find just the sensor coil under the engine covers, the blackboxes are in free air for better life conditions. Basically electronics don´t like much more than 80 degrees for safe operation, so a good concept to have them outside.

Vic
 

BigEd

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No external CDI units on my BT-H. I'm running 4 HT coils, 3 mounted under the cowl and one under the right-hand side of the petrol tank.
 

ClassicBiker

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Vic,
I take it you mean 80 degrees C. That would be 176 degrees F. That gives us an idea in both scales what temp we should be looking not to exceed.
Thanks
Steven

Ed,
When I said external CDI, I meant the BTH itself, which is a separate unit attached to the engine. Where on a Honda for example the magnet/rotor and trigger coil are all contained under engine covers.
Steven
 

davidd

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There is little magic with the BTH generator. A disc holding salami slices of magnets spinning over two primary coils.

PICT0004 (2).JPG


This unit failed when a piece of debris upset the rotating magnets by wedging itself between the rotor and the coils. BTH repaired it.

I think Steven is correct that most everything inside is not prone to heatstroke.

David
 

Vincent Brake

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Had 2 of them.
Both failed at higher rev.
In the end it was heat that killed them.

Internals used to be into insulating silicone.

Don't know it thats still the case after 10 odd years
 
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