ignition problems 1978 Ti40v Bonnieville

[Albyone]

I have just joined this forum out of frustration having my 1978 T140v for 11 years I have usually managed to sort any problems
however, having been to the 50th bonnie celebration 21st to 23rd at Gaydon ,After the 23rd runout to Meriden approx 55 miles the bike just died on me on return to Gaydon    
again on the way home , and again on the following day .when running the alternator is charging from 13v to 19v (changed the zenner diode as I felt it was not controling current to the batterybut it made no differance)
I might add that a Boyer Brandsen is fitted and beceuse it runs that is ok it also ticks over OK once hot .
As I had a spare solid state rectifier I have changed that too, cleaned and remade all terminals  arround the battery/coils/boyer unit .
I have new plugs /caps/ht leads/battery being deliverd.

HELP

Regards  Al Eleyhttp://www.vintagebike.co.uk/yabbfiles/Smilies/sad.gifhttp://www.vintagebike.co.uk/yabbfiles/Templates/Forum/default/cry.gifhttp://www.vintagebike.co.uk/yabbfiles/Templates/Forum/default/sad.gif

[L.A.B.]

If you are measuring 19V DC then you have a serious overcharging problem to start with, as the system voltage shouldn't really exceed around 14.6-14.9V ?

Boyer Bransden ignitions can be damaged if the system voltage exceeds 16V.

When it cut out, did you check for sparks at the plugs?

Bad contacts in ignition switches, kill switches, fuse holders, corroded connectors and bad earth connections are all known to cause strange ignition problems.
I suggest that you check every part of the ignition circuit.
Also check the pickup wires and connectors from the box to the soldered connections on the pickup, as the soldered joints can fail after many years of service.


How old is the battery? As a faulty battery can also cause problems?

  

[Albyone]

Hi L A B

It Was checked for a spark on the second and third occation and each time we did get a spark.

I have bypassed the kill switch (no longer operative)  and have re-soldered the fuse holder ,replaced all connections on the boyer unit and the coils
I have at the moment taken out the ignition switch as a matter of inspection test but I have yet to find a test proceedure which to carry out.

Regards Al Eleyhttp://www.vintagebike.co.uk/yabbfiles/Templates/Forum/default/rolleyes.gif

[L.A.B.]

As a test, you could try wiring the Boyer directly to the battery (with a fuse) and see if that cures the problem?

Are 12V coils still fitted?

As running two 12V coils in series (instead of two 6V coils) doesn't always produce the very best of sparks.

One option would be to return the ignition system to Boyer Bransden for testing?

  

[Albyone]

Hi L A B
[size=12]One other thing I did not mention is that the battery is just over 9 months old but I am having another deliverd as a precaution, the bike does not get a great deal of use and I usualy have it on a trickel charge,wheh not in regular use.

Regards  Al Eley[/size]

[L.A.B.]

Try to avoid cheap Chinese/Taiwanese batteries, as they don't seem to last very long on Bonnevilles because the vibration kills them!

I must say that's a very good example of a Tawny Brown & Gold '78 T140V.
My own '78 T140V would have looked much the same-when it was new, but not now!  

[Albyone]

Hi L A B

Yes they are the original coils and I have just done primerary wiring  test by removing the the minus connection on coil no2 then checking the other conection to earth and have achived 12v at each so the primeraries appear ok.
Yes if there is no other way to test the boyer then I would send it away

Rrgards Al Eley

[L.A.B.]

Boyer testing instructions:
http://www.boyerbransden.com/faultfinding.html
http://www.tioc.org/boyertest.htm

But you may want to consider fitting two 6V coils?
As I said earlier, two 12V coils wired in series (as you must do when using a Boyer ignition) will not be working at their full output, as they are having to share 12V between them, so are getting 6V each!