• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

Misc: Ignition New BTH "magneto" heat tolerance?

CoreyL

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
VOC Forum Moderator
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.
 

Robert Watson

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
VOC Forum Moderator
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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
 

CoreyL

Well Known and Active Website User
VOC Member
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
When I checked the temp of the cylinder head after a run it was ~250F. I didn't check the temp at the crankcase. I'll do that next time.
 

CoreyL

Well Known and Active Website User
VOC Member
As a follow up to my initial query, I went on my 1950 Meteor today with the newly reinstalled BTH magneto.

Ambient air temperature was 85 degrees F. I rode 35 miles without the magneto cowl installed. I came home and checked the temp of the crankcase near the mag and the mag itself. Both were 175F.

I then installed the mag cowl and went back out for another 55 miles of riding. When I returned home I re-checked the temp of the crankcase and mag. Again, they were both 175F.

So the presence of the cowl did not impact the temp of the mag.

The head temp close to the spark plug was 250F. I used a handheld IR digital non-contact type thermometer for taking the measurements.
 

Martyn Goodwin

Well Known and Active Website User
VOC Member
We - well some of us - use a heat insulating 'washer' between the head and the arb in an endeavour to prevent heat getting into the carb.

I wonder if that principle could be applied to the magneto? Of course, there is the issue of any spacer changing the alignment of the magneto pinion to its driving gear - but that could possibly be overcome with some prudent reduction in the face of the magneto flange or such like.

Just wondering ...........
 

eglijim

Well Known and Active Website User
VOC Member
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
If you fancy experimenting with other brands of ignition have a look at Ignitech cz, they make /sell a large variety of customisable electronic ignition systems for road and race machines as well as individual components and parts. May be a little tricky for you as they are ib Czekoslovakia but the website has an English option.
 

LoneStar

Well Known and Active Website User
VOC Member
We - well some of us - use a heat insulating 'washer' between the head and the arb in an endeavour to prevent heat getting into the carb.

I wonder if that principle could be applied to the magneto? Of course, there is the issue of any spacer changing the alignment of the magneto pinion to its driving gear - but that could possibly be overcome with some prudent reduction in the face of the magneto flange or such like.

Just wondering ...........
I insert a piece of woven-fiberglass exhaust insulation, with a foil outer layer, between the magneto and the crankcase (not the mounting, but along the length). The idea is to prevent some of the radiant heat from reaching the magneto. Not sure it helps at all, but it's invisible inside the cowl and couldn't hurt.
 

oexing

Well Known and Active Website User
VOC Member
Well, 80 degrees C should not be the big problem with electronics. But nevertheless electronics don´t live forever and there is no way to check before to know when the sh** dies. So my religion is electronics have to be small and cheap enough to throw one kit into the tool kit when going on a big trip. So a lot of all available stuff is not my choice for at least one argument. There is a good reason why up to this day not one certified piston aircraft flies with all electronic ignition - but yes, some of their magnetos are not great either and exchanged in 500 hours intervals.
I got my 12 V 200 W alternator system worked out and a real fat magneto. Else I´d have a contact or contactless coil ignition like the D type distributor.

Vic
 

oexing

Well Known and Active Website User
VOC Member
I found a VW Vertex/Ronco magneto for 4cylinder engines. No ATD springs inside, they have a combination of different flyweights for specific curves, very cool. But then, lots of tricks required with that mag but the sparks are extremely fat spun by fingers.

Vic
P1080030.JPG

P1090040.JPG

magneto flyweights:

P1070974.JPG

brushless motor 48 V 200 W for alternator
P1080818.JPG
 

Latest Forum Threads

Can't Find What You Need?

Buyer Beware: Fake or Real?

The Mighty Garage Videos

List of Forum Categories

Top