ET: Engine (Twin) Cutting Out

[nigsey]

C twin cut out while I was out for a ride, now sitting on side of road. Bike starts, runs fine, I get a few hundred yards down the road then cuts out without warning. Leave it a while, starts again and the process repeats. I have BTH mag with 276 carbs. Had the bike 2 years without a problem. Any suggestions as to what the case might be please? Nigel

 

[timetraveller]

Have you taken the petrol tank filler cap off or checked that the small hole in it has not got blocked?

 

[Vincent Brake]

could take of the magneto cowl, and let it cool thus

 

[Peter Holmes]

could take of the magneto cowl, and let it cool thus

I can't see it being overheating, he is in the very north of the UK.

 

[Bill Thomas]

I don't know how the BTH is wired,
But I had that on my Twin with Rita electronic ,
The front coil was faulty and that wired into the rear one,
So I lost the lot, Lucky I had a 12 v one in my bag,
You might lucky and have a bad connection ?,
The other thing is the cutout wire on those BTH ?.

 

[Michael Vane-Hunt]

Eugene had this problem. It was caused by his magneto kill switch wire grounding out.

 

[nigsey]

Thanks very much everyone. The fuel cap hole is clear. Not sure about fuel starvation particularly as the motor cuts out suddenly and doesn’t stutter to a halt. As for overheating I don’t think it’s that either, as Peter rightly points out I live in the north, I also tried it with mag cowl removed. I suspect it could be an intermittent electrical fault, perhaps the coils as Bill suggests. I guess it’s going to be a case of process of elimination. I’ll let you know the outcome, assuming I manage to find the cause. Back home now, embarrassingly on the back of a recovery vehicle. Note to self, don’t get your mate to tow you back home with a rope, accident waiting to happen!

 

[Bill Thomas]

I dread a breakdown now, It's putting me off riding,
Never thought about when I was younger,
When I think of what I have done , Without a Phone !,
Must keep keeping on.

I agree about towing, I tried it with Ron on an "A" Twin,
I was in my Mk10 Jag', It ended BAD.

 

[timetraveller]

It's a bit late now but if it happens again then take off one plug lead and try to see if there is a spark. You will need to keep the valve lifter open with an elastic or somesuch. If no spark then at least you are sure it is the electrics and you can start and go through those a bit at a time.

 

[Bill Thomas]

But not with a Rita ign , It will blow the magic box !!.