No Fire When Wet....

Had my Commando at our BritBike Owner's club BBQ on Saturday....bikes had to park up in a light but steady rain. After few hours of jaw wagging, time to head home. The other Commando fired up after few kicks. Mine did not. Maybe a few sputters here and there then nothing more after many many attempts. Checked for sparks, none to be seen. Battery, fuse & switch all good as lights/horn etc all working fine. Tried a different, never used spark plug someone had handy...still no spark across the gap. The decades of experienced classic brit bike owners on hand started to point the finger at my Vape-Wassell EI, which has been flawless since install some 6 yrs ago. Odd it would choose the first wet weather the bike has ever seen in this same 6 year period to give up the ghost? After more volunteers with fresher legs gave more kicks, we restorted to trying bump starts...but gave up after all runners were left panting for air following 4 or 5 attempts. We did have a very brief few pops out of bump runs then nothing more. One more spark plug out check, poor chap holding plug to cylinder head got a good shock in his hand...but still no sparks seen where they counted.

So I was consoled to await an auto club hauler to get me the 35 minutes down the road to home.

Upon arriving back home, gave everything a good spray down with WaterDispersant-40 and didn't have time until two days later to proceed with further investigations. Decided to first pull plugs once again to confirm the no spark issue....but that test proved to be a pass with flying colours...both plugs happily sparking away, with no other changes. Put plugs back in, gave her a tickle and she fired up second kick just like usual. So the EI was good after all. Now I'm just left with understand what was the cause.

I was running old school looking braided cloth wrapped over insulated copper wire HT leads. I'm thinking water might have wicked/seeped its way under the rubber coil end boots or plug end caps and either gave a short to ground or perhaps made too high a resistance btwn copper wire and coil or plug end crimped on metal terminals.

Other potential culprits?

Which way are your spark plug caps orientated? I notice a lot of Commandos have very short HT leads which result in the cable side of the spark plug cap facing forwards, that always looks like an invite for water ingress. I have longer HT leads that allow the spark plug cap to face rearwards.

Maybe water in the kill switch?

Hose the bike down and see it you can replicate the issue, then try a cable from the battery to the E.I. and see if it starts. If it does you can narrow it down further.

I think you answered your question , order new modern leads

daveforty said:

Which way are your spark plug caps orientated? I notice a lot of Commandos have very short HT leads which result in the cable side of the spark plug cap facing forwards, that always looks like an invite for water ingress. I have longer HT leads that allow the spark plug cap to face rearwards.

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Yes, that could be what was happening.....guilty as charged.

Craig said:

I think you answered your question , order new modern leads

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Got several sets....some modern rubbery leads with good NGK hard plastic/bakelite caps & rubber seals at the plug ends, another homemade set from Green Spark Plug Company parts...these have "bumblebee" unsheathed plastic/silicon leads and rubber Champion cap boots. The ones on that wet day were wrapped cloth with "Lucas" branded hard plastic caps, no rubber seal at plug ends.

cliffa said:

Maybe water in the kill switch?

Hose the bike down and see it you can replicate the issue, then try a cable from the battery to the E.I. and see if it starts. If it does you can narrow it down further.

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KS could be the issue...it is exposed with all the switch gear not sealed from elements really. I did give it a few presses while trying to investigate on the wet day...no effect. I have moved the original location on right side (lower??) position to the the left side upper position to allow for turn signal lever on left side. Might be more exposed there than stock location?

I don't know why people still use kill switches when they have a key ignition, in 50 years of riding I still to use a KS, with the Joe Hunt I have a hidden toggle switch, to me a KS is just a problem waiting to happen, broken wires, water ingest just to name a few as well go to start your bike and some fool has turned the KS too the off position.
Hate my modern Thruxton with all the safety cut out switches, just more things that could go wrong.
Funny how water can get into places you don't expect, but it's very important to have well sealed plug leads, before I brought my new Norton when I was 17, I had a TX 750 Yammy and any wift of rain it was a prick too start, lucky only had it for 2 weeks before buying the Norton.

Ashley

Every womble saturates all lectric conections in C R C , or suchlike . So Its There FIRST . so has no need to displacethe water , which itll do if you do it after .
They also fit icecream lids to the grill off their BMC mini or 1100 / 1300 , IN FRONT of the distributor . To avoid clogging the motorway with the things ,
In the wet .
Nowadays its White Vans at the head of every traffic jam , whereas traditionally it was a pensioner in a B M C 1100 , in a gentler age .

Matt Spencer said:

Every womble saturates all lectric conections in C R C , or suchlike . So Its There FIRST . so has no need to displacethe water , which itll do if you do it after .
They also fit icecream lids to the grill off their BMC mini or 1100 / 1300 , IN FRONT of the distributor . To avoid clogging the motorway with the things ,
In the wet .
Nowadays its White Vans at the head of every traffic jam , whereas traditionally it was a pensioner in a B M C 1100 , in a gentler age .

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No idea what a womble is, but Interesting to bring up the minis, as I was at a classic mini tech session our club put on two weekends ago. There we had discussions on various methods used in past to keep water off the ignition bits, including a large bendy bit of mill board behind the grill and even a dishwashers latex glove over the dizzy with fingers cut off to pass the ht leads out.
For the record I have no such contraptions on my classic mini. Has an EI under the dizzy cap and good silicone ht leads with tight fitting rubber boots at coil, dizzy and plug ends. I've been out in heavy rains at speed in that mini without issue.

When i had those symptoms it turned out to be a dodgy seal on the back of the points housing - letting water in and shorting out the EI.
1/2 hour with a squirter bottle eventually tracked it down.

ntst8 said:

When i had those symptoms it turned out to be a dodgy seal on the back of the points housing - letting water in and shorting out the EI.
1/2 hour with a squirter bottle eventually tracked it down.

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The wassell ei is fully epoxy encapsulated so should not be susceptible to water intrusion. But there is no seal on the points cover plate. Should there be?

Braided plug leads sound like something from Planet Bizzaro. Do they make and sell them as a practical joke?

Triton Thrasher said:

Braided plug leads sound like something from Planet Bizzaro. Do they make and sell them as a practical joke?

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Think I last saw braided plug leads on my Dads 1930s Plymouth. Sometime in the 1950s or 60s.

Does look very original on the appropriate machine.

I remember (non-braided) 1950s and 1960s HT leads being rather short-lived. They became cracked or porous or something and the car or bike would not start when wet or damp. A car engine running in the dark could look like a firework display with sparks all over the place.

Modern, cheap copper cored plug wire is a lot better.

Braided wires nowadays have modern insulation underneath and work well for me.
One of the few times my Norton let me down was during a huge thunderstorm. The spark was jumping from one of the HT terminals to the side primary connection. This is a Dyna Harley style coil. The holes where the HT leads plug in are shallow so the brass connector was very near the end of the insulated tower. It jumped across the coil well over 1" when wet. Fixed with new boots on both filled with silicone seal.
Russ

johnm said:

Think I last saw braided plug leads on my Dads 1930s Plymouth. Sometime in the 1950s or 60s.

Does look very original on the appropriate machine.

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Yes I got this exact colour of braided sheathed leads, more for the look. Put then on for past few months when going to shows etc. 'Course we've been in a drought for 4 months now and bike has never been in heavy rain since I've owned it, until this past weekend.
Will restrict running these until clear weather and at show events.

Guess having a small can of water dispersant in the kit bag might be wise on extended trips.
Its not something we need on modern vehicles since the ign systems have gotten so good. But in the past water problems on older setups was a real thing to deal with.

HT and water can be a bugger. Years ago I was convinced I had a cracked coil top as I could see this blue spark arcing. Turned out just to be damp, not wet, just damp.

Tornado said:

The wassell ei is fully epoxy encapsulated so should not be susceptible to water intrusion. But there is no seal on the points cover plate. Should there be?

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Mine was where the cables enter the rear of the points housing, near the tacho drive. I was missing the seal on cables and water would run in, the EI plate was a tight enough fit that water could puddle behind it.

ntst8 said:

Mine was where the cables enter the rear of the points housing, near the tacho drive. I was missing the seal on cables and water would run in, the EI plate was a tight enough fit that water could puddle behind it.

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Was not aware there should be a seal on the wires entering the points case? From memory, doesn't seem like there is much room between plastic wire sheathing and the hole inner diameter for a grommet to fit? Might do with a blob of silicone sealant.