Burned coil , why ?

[Kåre]

I need help to solve this problem.I have purchased a "conversion bike" R50 with a R60/5 engine.(The bike was not working when purcased)The coil was bad (BMW single dual lead) so I changed to a new single dual lead,- 70506 PVL german dual output coil for twin plugging R series ( the reason for using this coil is due to very little space/volume under the R50 tank). Well, ignition on,- but after 3-5 minutes smoke was coming from the coil and it was very hot! What is wrong? Wrong coil ?I have checked the electric ,seems ok- need help. (regads Kåre

[Ian MacDonald]

Kare, you do not say what battery voltage your modified R50 is using. The coils normally used when twin plugging an R series are 6 volt, with two wired in series across 12volts giving four spark plug connections. One wired across a12 volt supply will burn out. Was your bike running when the coil burnt out?
Ian

[Kåre]

Ian, thank's for the response. I have 12 v battery. The bike was not runninig when this happend. I have also now found on the internet (Chris Bynum's page) that he used a dual lead coil from Kawasaki . Kåre

[Ian MacDoanald]

Kare, if your bike was not running you could have an electrical wiring, points or condensor (Capacitor)problem.
The coil must have been passing current continuously to burn it out. With no coil connected-Make sure your points are open ,and with the capacitor disconnected ensure you do not have a short circuit to ground (-ve)
Check this before you fit a new 12v coil, Good luck
Ian

[Kåre]

Ian, today the supplyer of the burned coil confirmed it is 6 volt. (but they also recomended this one,- so I thought this one was ok). I must mention that the ignition was on , - and my understanding are in this case there will be passing current continuously through the primary all the time as long as the points are closed.- or am I wrong ?
I will do the check you recomend ,before I fit the 12 volt coil. Thank you for the assistance. Kåre