Original Mag vs BTH

[Rob H]

I have an old points system on my twin which could do with replacing. I initially considered electronic ignition but now thinking of going back to a mag.

Grateful for any pointers on the pros and cons of using an original mag (Dave Lindsey full recon) or a BTH.

Any views on which would be the best way to go or are they both pretty much the same in terms of performance and reliability?

regs
R

 

[Martyn Goodwin]

Get the original rebuilt and go with that. Ensured reliability

 

[davidd]

There has been a lot of info on the forum about this. I have had great luck with a BTH on my racer and would buy another. On the street, I suspect that rain would be an issue. I think the original mag may be a better choice for street use if you encounter wet conditions regularly. However, even the best builders are constrained by the parts that they are using. It seems that the best builder's mags can last a season of racing at best, but this may be many years of use on the street. Like Martyn, I would tend to lean to a good rebuild for the street.

David

 

[BigEd]

There may be other things you wish to consider before choosing your ignition system. If originality is important to you then rebuilding an original magneto would best especially if you already have an original magneto. If you do not already have your original magneto then the cost of a second hand unit plus a rebuild will bring you closer to the cost of a new BT-H unit.
Probably the least expensive option would be to go for an electronic conversion that fits an original magneto. With this option you really do need to have a good battery charging system if you intend to do much riding.
My personal experience is with a new BT-H unit fitted since September 2008 when the completed basket case twin Rapide returned to the road. Since then I have averaged around 8000 miles a year. In the UK we are known to have a lot of rain so quite a lot of those miles have been in very wet conditions. I had no problems with the magneto wet or dry which I was quite pleased with especially as I run four plugs with two coils under the cowl the other two coils bolted just under the front of the petrol tank.

I have an old points system on my twin which could do with replacing. I initially considered electronic ignition but now thinking of going back to a mag.

Grateful for any pointers on the pros and cons of using an original mag (Dave Lindsey full recon) or a BTH.

Any views on which would be the best way to go or are they both pretty much the same in terms of performance and reliability?

regs
R

 

[vibrac]

Please use the nomeclature BT-H to differntiate from BTH from British Thompson Huston of old
otherwise the (true) statement "The brass on the BTH on my Grey Flash is very shiney" will just confuse you....

 

[Martyn Goodwin]

I have an old points system on my twin which could do with replacing. I initially considered electronic ignition but now thinking of going back to a mag.

Grateful for any pointers on the pros and cons of using an original mag (Dave Lindsey full recon) or a BTH.

Any views on which would be the best way to go or are they both pretty much the same in terms of performance and reliability?

regs
R

Argh!! I pushed thewrong Key; This was the thread I meantto include

http://www.vincentownersclub.co.uk/showthread.php?5922-Poor-starting-on-new-Amal-and-BTH-Magneto

Sorry,

Martyn

 

[davidd]

Please use the nomeclature BT-H to differntiate from BTH from British Thompson Huston of old
otherwise the (true) statement "The brass on the BTH on my Grey Flash is very shiney" will just confuse you....

I find the use of nomenclature interesting. I used "BTH" in an email to Bill Hoddinott once and he corrected me by saying that it should be "BT-H." Later when Bill was corresponding with Barry Basset, who worked for BTH, Barry noted that "BTH" was also used extensively by the Company and it did not differentiate. I certainly do not mind adhering to Tim's solution, but I do not know if others will note the distinction as intuitive.

Personally, I have resisted using "Grey Flash Replica" in my usage, but it is so widely accepted that it is difficult to communicate effectively without accepting it. My understanding of the use of the word "Replica" is that it was a factory built machine. Thus, Vincent manufactured a "TT Replica." If you owned a Comet and modified it into a TT Replica it would be a copy, not a replica. However, the usage has changed and now the first meaning of replica is considered "copy" and a the "factory built and supplied" meaning is way down the list if it is even on the list.

Recently, I was emailing someone about the Grey Flash manifolds that were made by the Factory and I was corrected. They are "adaptors" not "manifolds." I will be reading my Vincent literature with this in mind.

David

 

[Howard]

AAAh. When is a Grey Flash not a Grey Flash? If you take a Comet, swap all the non Flash parts for Flash parts and paint it grey, what have you got? Why are only factory built Flashes, Flashes? I would guess most of the Flashes (used ones) have had most of their non Comet parts replaced by non factory mechanics.

H

I find the use of nomenclature interesting. I used "BTH" in an email to Bill Hoddinott once and he corrected me by saying that it should be "BT-H." Later when Bill was corresponding with Barry Basset, who worked for BTH, Barry noted that "BTH" was also used extensively by the Company and it did not differentiate. I certainly do not mind adhering to Tim's solution, but I do not know if others will note the distinction as intuitive.

Personally, I have resisted using "Grey Flash Replica" in my usage, but it is so widely accepted that it is difficult to communicate effectively without accepting it. My understanding of the use of the word "Replica" is that it was a factory built machine. Thus, Vincent manufactured a "TT Replica." If you owned a Comet and modified it into a TT Replica it would be a copy, not a replica. However, the usage has changed and now the first meaning of replica is considered "copy" and a the "factory built and supplied" meaning is way down the list if it is even on the list.

Recently, I was emailing someone about the Grey Flash manifolds that were made by the Factory and I was corrected. They are "adaptors" not "manifolds." I will be reading my Vincent literature with this in mind.

David

 

[Bill Thomas]

Time/trav' after looking at a photo of my L/ning rep', Told me the engine was not Black !! That was the last thing I was worried about, Getting T.T. carbs and the exhaust etc was all I thought about, I think it's daft, they are all the same cases. People are always asking me what my bikes are, I think I should say, Just a box of Bits !! How many bikes are Standard ? Cheers Bill.

 

[greg brillus]

Ah yes....when is a Vincent not a Vincent....A true Vincent entheusiast wouldn't give a Rats A--- It's only the investor / collectors out there that apparently know better....but then, their machines never get used......do they..!!!