Engine cut out at 60 MPH.

[2VEZR25]

Anyone got first hand experience as to what the might cause of a brief engine cut out when running at speed?.. It occurred several times recently while out on a ride while traveling at 60mph. Just as quick as the motor cut out it would start again. It had been running fine all day when the fault came in 3 or 4 times and then things came good again and ran sweet for the rest of the day??.. Bike is a 91 R100RT. It hasn't been messed with in terms of wiring and it wasn't so long ago that I went through all of the connections to make sure everything was clean. The ignition module was serviced recently with heat sink paste and the electrics have never played up before. Anyone with similar experience find a likely suspect?

[RecycledRS]

Intermittent electrical issues are a bixxxxch to find. First check the simple stuff like battery connections and ground connections Next try wiggling the ignition switch, stop switch and clutch switches to see if you can make it happen again. If no luck there I'd start cleaning all the connectors and wiring harness since its about time anyway. Best of luck.

[pommie john]

I'd be looking at fuel filters too.

[carpetburn]

water in your fuel, check filters as mentioned and drain tank into a clean white bucket[so you can see water]

[bikerfish]

I've had that happen and in my case it was the bean can. That said, best to start with the simple and cheap things first, like said above, fuel filters and such. drop float bowls, etc. Also, ground wires.

[RaystheBMW]

I've had a few such events and it's very disconcerting. In my case it was the ignition module heat sink paste, not once but twice. The first time I used some leftover hobbyist silver stuff meant for computers. That worked fine for a few months, but when the exact symptoms happened again, I took it back apart and replaced it with the white stuff (sorry I don't have the brand name). It's been several months now, and hasn't missed a beat since.

[2VEZR25]

Thanks for the suggestions people. Checks completed so far; Tank has been drained, fuel filters & float bowls checked. No water or restrictions were seen. Ignition module removed and heat sink paste checked (OK) and replaced again just as a matter of course. Ignition switch wires wiggled with engine running and all is in order. Will have to monitor for a while and carry a few more spares.

[97oilhead]

Did you check the battery and ground connections as suggested?

[eepeqez]

I've had a 1984 R65 do that because of corroded battery leads...

[baldwithglasses]

Fuel cap venting?

[trophymoto]

coil cracks?

[mykill]

Is it just the engine cutting out or are any lights going out? You say it dies briefly and restarts. Does this mean you poke the starter and it starts up or you let the clutch out and it resumes? is it just a hiccup?

[eepeqez]

Cracked coil failure (also Hall effect pickup in the beancan failure) tends to stop dead and not go.

Fuel cap not venting tends to be very variable depending on the volume of air in the tank, and is much less sudden than electrical issues.

When I had similar symptoms on my R65, the alternator warning lamp would come on when the ignition died (because the Df terminal of the alternator was powered by the alternator through the diode board and the other items on the ignition switch provided an earth path) and everything else would go out.

The visible effects of a +ve terminal failure are almost exactly the same as turning the ignition or kill switch off with the motor running.

Seriously, check the things which are most likely and simplest to check first. Usually this means check the fuel tap and kill switch! In this case, obviously make sure your kill switch isn't getting dodgy by gently wiggling it and seeing if it kills the motor when it shouldn't.

Then check for corroded battery leads and terminals including terminal fittings which are not making good contact with their leads, which are not visually obvious but are easy to check and are likely to cause exactly the symptoms described.

[Houseoffubar]

Originally Posted by baldwithglasses

Fuel cap venting?

Ha ha, always the first thing I think of! First time I saw it, I was so surprised I slapped my forehead....Doh! Mine was the tank bag sealing around the cap.
I saw a lot of tanks destroyed when I worked at the Ducati / Yamaha dealer, bad gas cap vents, caused the tanks to implode when brought in out of the sun!

[2VEZR25]

Thanks guys for all of your suggestions. To answer a few of your tips; Yes the ground terminals and all connections have been checked. I found one of the main connectors plugs was not making full connection and so I suspect this may have been the problem. I agree that the hall trigger would more likely have been either working or not rather than it being and intermittent factor. At least that has been my previous experience with failed hall triggers. I will test it again now the the wiring connector has been properly seated and wait to see if the symptom returns. I am not suspecting any fuel venting issues at this stage as the engine cut out was too sudden and not typical of any fuel starvation issues.

Regards further ignition system diagnostics; I was in the process of trying to remove the #5 pin from the ignition module harness plug to test for voltage, as per the workshop manual, but I found that I could not lift the one way locking detent from the plug.. I was using a piece of thin flat stainless steel filed to fit in the channel where the detent should be, but no matter how I tried to poke and prod I was not able to lift it. Has anyone got any advice on how to best remove the #5 terminal wire from the plug connector?