New BTH magnetos

Has anyone used the new BTH magnetos? I'm looking for feedback.

Did not know they were available again. Do you have a link?

Slick

I haven't got one but my riding mate has a 600 Norstar fitted with one. It's excellent & starts the bike first kick nearly every time. It is also very easy to set the timing. The only down side is the price, but it's only money & if you don't spend it the benificiaries of your estate will.

I have one on my Norton Metisse (single) it has worked brilliantly and makes for easy starting, expensive yes, but worth it in my opinion!

Earlier in the year I installed one on my Vincent Rapide, as I was getting tired of issues with my 72 year old original that had been rebuilt multiple times.

The BTH has performed extremely well, the bike starts easier and the performance feel much sharper through out the rev range. As I have an electric starter set up, I appreciate the fact that it totally independent of the electrical system and having state of the art internals, means it is much more precise.

Not cheap but well worthwhile in my case.

I've found their website. It seems these units require an external coil to step up the primary voltage to high tension. Or am I missing something?

Can someone explain how they work?

Slick

texasSlick said:

I've found their website. It seems these units require an external coil to step up the primary voltage to high tension. Or am I missing something?

Can someone explain how they work?

Slick

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Yes, mine came with two very small externally mounted coils.

according to the fitting instructions on their website, they use small external coil/s . They do not need a power supply from the battery.

Good to hear. I'm considering putting one on my Goldstar. Cheaper than a Joe hunt.

From what I glean from their FAQS and fitting instructions, these units are like an EI with the exception that they source their own power. Advance, coil saturation, and coil switching are done electronically like an EI, and are thus at risk of a component failure that might shut you down. Only gain over EI is no battery dependency.

I like the looks, especially the K2F replica version, but I think the JH will prove to be more reliable with good ol' fashion cam actuated points for switching, and mechanical HT distribution. It is likely that the JH exhibits the true magneto characteristic of greater spark intensity at increasing RPM , but the BTH may not, and if not, the BTH is not a true magneto.

Interesting..... I will keep an open mind about these .......

Slick

texasSlick said:

From what I glean from their FAQS and fitting instructions, these units are like an EI with the exception that they source their own power. Advance, coil saturation, and coil switching are done electronically like an EI, and are thus at risk of a component failure that might shut you down. Only gain over EI is no battery dependency.

I like the looks, especially the K2F replica version, but I think the JH will prove to be more reliable with good ol' fashion cam actuated points for switching, and mechanical HT distribution. It is likely that the JH exhibits the true magneto characteristic of greater spark intensity at increasing RPM , but the BTH may not.

Interesting..... I will keep an open mind about these .......

Slick

Click to expand...

I like the idea of the JH magneto, but the lack of an auto advance always stops me.

I've run a BTH on my Velo Clubman for many years. One kick starting, and nice build quality.

jamesp said:

I like the idea of the JH magneto, but the lack of an auto advance always stops me.

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They don't really need auto advance to start easy or run, have proven this on two JH magneto's and 22+ years of running experience on both Triumph and Norton, but it seems the people who make a big deal about this are ones who have never any experience with a JH magneto's.

ashman said:

They don't really need auto advance to start easy or run, have proven this on two JH magneto's and 22+ years of running experience on both Triumph and Norton, but it seems the people who make a big deal about this are ones who have never any experience with a JH magneto's.

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I do not have JH magneto experience, but I do have drag racing experience both on the strip and off the strip. I have years of experience fine tuning Holley, Carter, Bendix, Amal, and Quadrajet carburetors in conjunction with tuning distributor mechanical advances using weights and springs either by the seat of my pants or on a distributor machine. My experience has taught me that a properly functioning centrifugal advance and carb tuning is important for street driving to give the motor what it likes. I just don’t see how you can do that with a fixed spark. A fixed spark is ok for wide open throttle as is common on drag cars that leave the line at high RPMs on their way to full throttle, but a street machine needs a tune-able advance system for best operation, IMHO. Its great that the JH has a powerful spark, but I think there is more to it than that for optimum engine operation. I know that the electronic ignitions used on our bikes do not have a tune-able advance mechanism, but they do have one. BTW-the best magneto I ever had was on my 1958 Cushman Eagle when I was 14. Not only did it run the motor, it also ran all the lights very brightly. Now that was a magneto.

I have used a JH on an Atlas and it runs the best from 3 different ignitions.....a rebuilt K2f. Pazon and a JH. The JH was clearly the winner, the pazon was the runner up. My main goal is to have an ignition in the goldstar that does not have a battery. The BTH will do the trick and give a good advance curve. And it's a little cheaper than the JH. JH is reluctant to sell me the single fire mag claiming it is hard to time. They can give me no info. Now to sell the B50 to fund the project. Anyone need a B50 for $3500?