New style BT-H mag

[davidd]

Craig,

I am sorry that I have never had one apart. Maybe I am not. I have never had one serviced either. Except for the bad ground I never had a sparking issue. I probably only have four or five thousand miles on it and I usually run 4300 rpm to just under 7000. I have run it up to 8500, but prefer to stay under 8000 for the top end runs.

David

 

[craig]

I opened my BTH cover for a look inside. I see an rotating arm with a magnet passing a small coil, electronic module, several ground locations. I will try and post some photos.
The rotating arm is clamped to the main shaft with a squeeze clamp action and appears to be what is set to timing spec. Loosening the clamp and moving the arm would allow adjustment of fire point, as i see it. Anyway, i am glad i looked inside to become familiar with the innards.
Craig

 

[BigEd]

Dear Craig,
It is not quite as simple as that. The relationship between the positions of the rotating parts and triggers is synchronised for optimum performance and correct firing point. Units that have been opened for "a look inside" may not perform correctly afterwards because our innate mechanical curiosity sometimes leads to more than just looking. I try to do all repairs and adjustments to my bikes myself. Sometimes I just don’t have the knowledge or skills for some things as I have unfortunately learned to my cost.
Bench testing may not always show a fault as it is difficult to truly replicate the varying on bike running conditions of load, speed, temperature, etc.
Your bike ran OK with a borrowed Lucas unit so that suggests that your problem lies in the BT-H unit. If the internal component settings are unchanged then it is possible that the electronics are failing. Perhaps it might have been easier to accept the manufacturers offer to replace the cdi/coils, etc before returning it to you.

I opened my BTH cover for a look inside. I see an rotating arm with a magnet passing a small coil, electronic module, several ground locations. I will try and post some photos.
The rotating arm is clamped to the main shaft with a squeeze clamp action and appears to be what is set to timing spec. Loosening the clamp and moving the arm would allow adjustment of fire point, as i see it. Anyway, i am glad i looked inside to become familiar with the innards.
Craig

 

[craig]

Dear Ed, Interesting response. I an guessing you responding on behalf of BTH?
My last phone conversation with BTH went something like this -
BTH to Craig - "We have tested this unit for 6 hours on the bench and it is perfectly fine. In fact it tests as well as any new unit and we would be happy to offer this as a new unit. We could replace the internal parts or other components, but it would be an incredible waste of money."

As you can see, this is not an offer to replace anything. It is advice to not replace anything!

I am not suggesting that there is a problem with my BTH.
Cheers
Craig

Dear Craig,
It is not quite as simple as that. The relationship between the positions of the rotating parts and triggers is synchronised for optimum performance and correct firing point. Units that have been opened for "a look inside" may not perform correctly afterwards because our innate mechanical curiosity sometimes leads to more than just looking. I try to do all repairs and adjustments to my bikes myself. Sometimes I just don’t have the knowledge or skills for some things as I have unfortunately learned to my cost.
Bench testing may not always show a fault as it is difficult to truly replicate the varying on bike running conditions of load, speed, temperature, etc.
Your bike ran OK with a borrowed Lucas unit so that suggests that your problem lies in the BT-H unit. If the internal component settings are unchanged then it is possible that the electronics are failing. Perhaps it might have been easier to accept the manufacturers offer to replace the cdi/coils, etc before returning it to you.

 

[BigEd]

Dear Craig,
I am not replying on behalf of BT-H. My position is that the designer and former owner of the company is a very good friend so I have some small knowledge of the BT-H unit. I was in contact with the new owner of the company and I asked about your unit. I got the impression that he had perhaps suggested replacing some parts, maybe I misinterpreted what was said.
I hope you don't see this as interfering as my intention is to help anyone where I can to get their Vincent running as well as possible.

When my friend owned the company on a couple of occasions he had (twin) Vincent magnetos where the customer was having problems. On the test rig these ran up OK. I offered to fit these units to my Rapide to see if they performed differently when actually on a bike. Fortunately in both these cases the units performed well on my Rapide. Would it be possible for your friend that loaned you the Lucas unit to try your BT-H unit on his Comet to see if he experienced the same running problems?

Dear Ed, Interesting response. I an guessing you responding on behalf of BTH?
My last phone conversation with BTH went something like this -
BTH to Craig - "We have tested this unit for 6 hours on the bench and it is perfectly fine. In fact it tests as well as any new unit and we would be happy to offer this as a new unit. We could replace the internal parts or other components, but it would be an incredible waste of money."

As you can see, this is not an offer to replace anything. It is advice to not replace anything!

I am not suggesting that there is a problem with my BTH.
Cheers
Craig

 

[craig]

Hello vin998, How did you determine the generator portion of your BT-H had failed? Thanks Craig

There is another possibility. The two seperate cdi units (one per cylinder) have a common power source I believe. So if the built in generator is failing intermittent then it would effect both cdi units. My BTH died as the generator part of the system failed.

 

[Simon Dinsdale]

Hello vin998, How did you determine the generator portion of your BT-H had failed? Thanks Craig

Hi Craig,

After discussions with the original owner of BTH (now under new ownership) he said that the only common component to both cylinders is the rotational drive and the internal generator. The two cylinders have seperate pickups and electronics.

Now at work I have the capability of measuring high voltage pulses. I looked at the output of both coils at 200rpm shaft speed which is the equivalent of 400 rpm crank speed which is approx what the kickstart speed is. At this speed there was no output at the coils. Had to spin the BTH at 500 rpm to get a output that would break down a spark plug. That is 1000 rpm crank speed. Way to high for kickstart and was confirmed by the bike would only start when bumpstarting. Tried this with the spare coils I had and got the same result, so it was not the coils as sugested at the time.

Now this is a unit that when I first got it would start the bike with the slightest of kicks, and as the failure was occuring on both cylinders the conclusion was the failure must be in the only common part of the BTH to both cylinders - the internal generator. Now I don't know how the internal generator works as I have not dismantled the unit that far. When I discussed this with Tony at BTH he sort of agreeded with my conclusion but would want to look at the unit (at a cost). I have got to admit with the bike running great on std coil ignition, the BTH unit has been put in the back of the garage and not looked at since. To me reliability is everything as I do travel a lot on the bike and so even if it was fixed I don't think I could trust it again.

Just realised Craig yours is a Comet. So you won't be able to use the conclusion of "the only common part of the BTH to both cylinders". Now if I had seen a difference between the outputs of both coils (was a unit for a Rapide) I would have concluded that a electronic CDI unit for that faulty cylinder was the problem after eliminating the coil and HT leads etc.

 

[Rob H]

Hi Craig, been following this with interest as deciding whether or not to go the BTH route, any update?

 

[craig]

Hi Rob, Yes,i will follow up , but just have not had time yet to put into words my work and thoughts on this BTH. BTH emailed that they were moving, so didn't send this unit back. I also emailed about what testing they could provide, but only recieved an email stating they were on vacation. Please dont get my posts on this subject wrong, i want this BTH to work......i like the electronic advance, stock appearance, no battery required and no ATD!
More later
Craig

Hi Craig, been following this with interest as deciding whether or not to go the BTH route, any update?

 

[Mark Fisher]

Just to add a little balance here, I have to state that i fitted my BTH to my shadow in 2009 and it has now done 15,000 miles and, quite frankly I'd almost forgotten about it because I have never touched it since...I guess thats a good thing!
mark