Todays problem - Faulty Coil ??

[BillN]

1985 R80 mono..less than 30,000 miles.....well looked after and maintained

Symptoms
Took my R80 out today, (yesterday)...........it stalled at most "stop signs".........would not bump start...........started with effort "on the key"............got progressively worse during the 40 mile ride, stop restart routine.............finally refusing to start for about 30 mins.................there appeared not to be a spark, (I was at the road side sweating like a pig....and it was quite sunny), floats were full..............no smell of fuel, no leaks etc., and it did not appear to be flooding........plugs and plug leads seem OK.....

Question
will a faulty coil cause the Bike to cut out when stopped at a road junction.........but ride OK at higher revs, once started ....worsening the hotter it gets.............the answer is yes...........

I also spoke to the BM Club Airhead Tech guy, (I am an old git), who suggested that I should also check the Bean Can, (Trigger Unit), as maybe the A/R mechanism was sticking, (say at fully advanced i.e. over advanced at low revs)...but I checked that and it is "springing" back OK.

Seems it is the Coil???????...........(the Bike has the original coil) and the older coils, (as you all know), have a reputation for "breaking down"

Coincidentally, (I must be psychic), as I bought a K100 coil off EBay a week or so ago, thinking that one day I may need a spare.........but now cannot check the Bike for a couple of week??

Anyone had this problem?

 

[Big Jets]

I used to carry a spare coil on my 85 r80 failed twice on me .It was intermittent then one day it chucked it altogether had spare coil under the seat switched it and off I went no probs .I carry a spare on myG/S.

 

[Rob Farmer]

I recently fitted a Dyna coil to my mono. Big improvement through the rev range.

Have you measured the resistance the primary and secondary windings of your coil? The problems you're describing could be down to a lot of faults. I had a similar issue on a Paralever 80 GS that turned out to be corroded connections on the plug to the amplifier unit itself. Waggling the plug about got me going for a short time before it cut out again. A new ignition module and new connectors in the plug sorted it out.

I have a genuine ignition amplifier unit tester if you ever need any testing out. All FOC of course

 

[shafted]

Yes on both count's (duff coil & duff trigger unit).

If it's the coil then I had a long thin hair-line crack in the casing. It just would'nt fire up at all, at any time. I put in the double coil off a K75.

The trigger unit went belly-up on the way to Portugal. That had to cool down before being able to fire-up again. Once it was going it would only last a couple of mile's before the engine died again (luckily I had a spare one).

I put a new Hall Effect Sensor in the broken trigger unit. This is one thread; thttp://www.geocities.com/fwarner_au/mc_things/bmwr_ign_sensor.html

Another; http://www.deathstar.org/~flash/ig_trig.html

Would'nt like to say what's causing you're problem as they can both display the same symptom's.
Safe riding Karl.

 

[BillN]

I recently fitted a Dyna coil to my mono. Big improvement through the rev range.

Have you measured the resistance the primary and secondary windings of your coil? The problems your describing could be down to a lot of faults. I had a similar issue on a Paralever 80 GS that turned out to be corroded connections on the plug to the amplifier unit itself. Waggling the plug about got me going for a short time before it cut out again. A new ignition module and new connectors in the plug sorted it out.

I have a genuine ignition amplifier unit tester if you ever need any testing out. All FOC of course

Thanks Rob...........I am out in France for another few weeks........so I have limited options.........I am a real numpty at testing electrical bits, ........what I usually do is swap bits between Bikes until it solves the problem.......but I will take the tank off tomorrow and have a good look at all the electrical connections..........and hope that the problem lies there.

Cheers

 

[Steptoe]

. I put in the double coil off a K75.

.

The K75 coil is a single output, can't be used like a K100 dual output coil ???

 

[shafted]

Think it has a single coil and a twin coil?? Or so M/W told me when I bought it.
Safe riding Karl.

 

[Rob Farmer]

If you get stuck Bill I have a spare Ignition coil and a new ignition amplifier. Just let me know and I'll post them to you

 

[shafted]

Ignition control unit - Lucas DAB 400. Can be bought cheaply at car factor's.
Safe riding Karl.

 

[Steptoe]

Think it has a single coil and a twin coil?? Or so M/W told me when I bought it.
Safe riding Karl.

K75 has three single coils. And special plug socket for electrical connection , not spade ends.

 

[shafted]

Well I'll be darned, must have been off the K100.
Safe riding Karl.

 

[(RIP) Proff]

K75 has three single coils. And special plug socket for electrical connection , not spade ends.

Does "SIR" have one of those connections?
and would he be prepared to part with it??
I've a spare K100 coil but its the plug type not the spade connectors.

 

[Steptoe]

Well I'll be darned, must have been off the K100.
Safe riding Karl.

No good to anyone posting wrong info

I've a spare K100 coil but its the plug type not the spade connectors.

That'll be from a K1100

 

[BillN]

If you get stuck Bill I have a spare Ignition coil and a new ignition amplifier. Just let me know and I'll post them to you

Cheers Rob......I should be OK......I may be able to pick up 2 secondhand 6volt VW coils locally to test the coil....or just leave it until I come back out here in September.......anyway I can now get on with some kitchen tiling etc.,

Thanks

 

[BillN]

Just taken the coil(s) off to have a look...seems to have got hot on the RHS as the bakerlite equivalent is blistered.....(but maybe this blister effect is normal......


As Rob suggested I will get it tested in a couple of weeks

Edit:....the plug leads are 25 years old........think I will treat the Bike to a new set....any suggestions?

 

[BillN]

I recently fitted a Dyna coil to my mono. Big improvement through the rev range.

Have you measured the resistance the primary and secondary windings of your coil? The problems you're describing could be down to a lot of faults. I had a similar issue on a Paralever 80 GS that turned out to be corroded connections on the plug to the amplifier unit itself. Waggling the plug about got me going for a short time before it cut out again. A new ignition module and new connectors in the plug sorted it out.

I have a genuine ignition amplifier unit tester if you ever need any testing out. All FOC of course

Just bought a multimeter from the local supermarket?

The resistance on the primary is 1.6 ohm, (starts at about 2.0 then drops)
The books says 1.15 to 1.32

The resistance on the secondary is 8.53 K ohm
The books says 7.5 to 9.15