V50 3 ignition problem

I have developed an ignition problem with my V50 3. When starting off from cold I go about 1 mile then engine cuts out completely, no coughing or spluttering, just cuts out as if I had hit the kill switch. As soon as it stops have tried the spark plugs and no sparks. After about 5 mins it will restart and then run for about 800 yards then die again, again after 5 mins it will restart and go for another short distance. As the mark 3’s have a completely duplicate ignition systems for each cylinder I cannot fathom out why it fails completely, surely I cannot have both components failing at the same time? Any ideas please?

Do you have a wiring diagram? If so, you need to be looking for a common failure point that affects both sides I would think. Perhaps a dodgy bit of wiring that gets hot.
I think this will have points rather than electronic ignition?

This is a long shot but it happened to me and took ages to figure out as it was a hidden problem. My v50111 would fire up and off I go down the road and at a certain speed the ignition failed as if the kill switch had been activated. I would pull in the throttle, slow down and the ignition would fire up again and when I got up to the same speed as before it would cut out again. Everything in the ignition system was checked and all appeared functioning so I drew a blank until I eventually saw what was happening. The live feed from the battery to the ignition system was loose so when I got to a certain speed the wire under wind pressure would pull away from the connector just enough to cut the ignition system so when the bike slowed down and the wind pressure on the wire reduced it went back into the connector - so you can see it was a hidden problem, visually the connector looked fine and tested OK for connectivity, what I failed to do was to pull it. I would love to hear if your machine is suffering from the same issue - if not it is likely to be a wiring issue and I would suggest it is the live feed cutting out somewhere along the system - the moral of my story is don’t take things on face value - pull them!

Don’t need the wind sticking its oar in! Complicated enough as it is. :smiley:

It might be worth running a temporary (fused) wire direct from the battery to the common live side of the ignition unit (with some means of isolating eg a bullet connector). Also something similar for the earth side although this is probably less likely to be the culprit. If nothing else this would eliminate these areas.

Many thanks to those who sent helpful replies to my query. I have found that there is one feed to the coils, this passes through the 15 way connector, the ignition switch and the kill switch. There has been some alteration to this, the red wire from the battery does not go through the 15 way connector, it has been bypassed by a short piece of wire and 2 terminal strips. Also the wiring around the coils appears non standard, involving bullet and spade connectors, the coils are Nippondenso, does anyone know if these would have been original equipment? The rest of the electrics are Bosch.
I have tried the idea of running a fused lead from the battery to the coils and the bike runs fine like this. Several of the connectors around the coils are corroded so will try replacing these next.
Thanks again friends, first time I have used the forum and am impressed by the speed and helpfulness of the replies. Stay safe.

If you would like a coloured wiring diagram for the V50 III, send me your email address via PM

Wiring diagram sent :smiley:

It sounds as though it’s just a bad connection somewhere between the battery and the coils as connecting direct seems to eliminate the problem. I’d just carefully examine each connector and get rid of the non-standard link you mention. It could also be poor connections within the ignition or kill switch.

The coloured wiring diagram should help although I sometimes find difficulty relating the colours I find on the bike with ones on a diagram!

Hi, I had the same problem with my Monza. Tried all the obvious fixes, wiring direct to the coils to by pass the ignition etc but no cure. Replace both coils and the problem went. Monza had been standing for years before I got her so coils may have deteriorated due to no usage? Also found that the as the original airbox had been changed for K&N’s the heat from the engine goes straight to the coils. This caused me problems in a traffic jam on a hot day when I had intermittent firing, this went on for 40 miles then the bike stopped and would not start. Have now bought new coils again Doh!, but will be fitting a st steel plate underneath them to reflect the heat. Will also move them closed to the front to get more air flow.
Hope this helps,

Hi Jim. Thanks for your ideas on my problem with my V50. Mine seems to run fine with the coils wired directly to the battery so suspect problem lies in the circuit ignition switch/kill switch/15way connector. Have heard that ignition switch can give problems(mine is the original) and the kill switch was replaced by the previous owner. Will try replacing the ignition switch first. Thanks again. John.

V50’s generally are quite old now so I would concur that switches & connectors are suspect.