The last duff coil, (1986 - R80 mono - the original coil - therefore over 20 years old when replaced), I had read
Resistance on the primary was 1.6 ohm, (starts at about 2.0 then drops)
The books says 1.15 to 1.32.......for all models from 1981 0n
Resistance on the secondary is 8.53 K ohm
The books says 7.5 to 9.15
hair line cracks can be almost invisible and look like fine scratch marks
If your readings are not within the specified range then something is wrong......you can always take the Coil to a BM dealer of good auto electrician for accurate testing on a spark gap tester, (this advice taken from Haynes - I have never done this). Then you will know for sure if it is faulty
Most of the simple electrical test are in the manual which I have put on one of my web sites.
You can download it here
it is a big file so it may take some time to download............then save it to you desktop, (computer)
Just read through the relevant section and try to eliminate each electrical component
Good luck
Resistance on the primary was 1.6 ohm, (starts at about 2.0 then drops)
The books says 1.15 to 1.32.......for all models from 1981 0n
Resistance on the secondary is 8.53 K ohm
The books says 7.5 to 9.15
hair line cracks can be almost invisible and look like fine scratch marks
If your readings are not within the specified range then something is wrong......you can always take the Coil to a BM dealer of good auto electrician for accurate testing on a spark gap tester, (this advice taken from Haynes - I have never done this). Then you will know for sure if it is faulty
Most of the simple electrical test are in the manual which I have put on one of my web sites.
You can download it here
it is a big file so it may take some time to download............then save it to you desktop, (computer)
Just read through the relevant section and try to eliminate each electrical component
Good luck