No spark? My wife to the rescue!

[Drew400]

I have Boyer Bransden electronic ignition on my 400/4 with standard coils. It pre-dates my ownership of the bike and so the system is at least 10 years old.

In the last year I have had two or three occasions when the bike wouldn't start after a few weeks in my garage (dry & heated and battery mate used constantly). The cause = no spark. So off with the timing cover on the assumption of condensation. On the first occasion that was enough to sort it. Fine.

On the second occasion, I ended up removing the blue & yellow wires that attach to the stator plate. Touching them together with the ignition on forced a spark and, after re-fitting, the bike fired/ran with no problem.

This time (lovely warm February day tempted me out to test my new helmet) all suited and booted but no spark. Off with the timing cover, etc. This time still no spark after the previous exercises so I contacted Boyer Bransden. They replied almost immediately (that's always a good sign).

Their first tip was use an ordinary hair dryer to warm the ignition unit that resides under the seat. So I borrowed my wife's hair dryer and, hey presto, big spark and the bike running fine again.

I don't know of any blokes who own their own hair dryer, but I'm going to become one, if only to keep in my garage.

I couldn't see any evidence of this being posted before suspect I'm not the only one to have experienced this 'phenomenon'.

PS - I rang Boyer Bransden to ask why this worked. They said something about chemicals in the capacitors responding to heat. Fair enough!

[Tomb]

I don't know of any blokes who own their own hair dryer, but I'm going to become one, if only to keep in my garage.

A lot of us have an old hair dryer for softening carb rubber and the like, I certainly don't need for my head, razor does that and saves on paying barbers 

[Drew400]

 Ha ha, good point. Clearly, my tool box has been sadly under-equipped!

[SteveW]

Chemicals in capacitors responding to heat?

Never heard that before and I’ve been an electronics engineer since 1984.

[hairygit]

Well, I can only say in all my years working with individuals riding these old Honda's I have NEVER had to do that with points and condensers! Even in my reckless youth my 750F1 would live outside, uncovered, and ridden all year round. One morning during a real cold spell (early 1980's) it was minus 14, and it started on the button, as easily as a summer day, The clutch cable had frozen, but after a couple of pulls that was okay as well. First couple of brake applications were interesting though, both discs coated in ice!

Sent from my POT-LX1 using Tapatalk

[Drew400]

Quite so. Old technology is usually reliable (and understandable) technology!

[mike the bike]

Is the cork gasket in place?  Add a snob of silicon/ Sticks like sh*t to seal where the wiring goes in.

[Drew400]

Yes indeed. Done that. Thanks for the tip.

[Sprocket]

Chemicals in capacitors responding to heat?

Never heard that before and I’ve been an electronics engineer since 1984.

Really? This is pretty much my go-to when dealing with anything old that suddenly stopped working....
https://en.wikipedia.org/wiki/Capacitor_plague

[Drew400]

Gosh, that link's a pretty fulsome answer! Thank you.

[AshimotoK0]

Chemicals in capacitors responding to heat?

Never heard that before and I’ve been an electronics engineer since 1984.

Really? This is pretty much my go-to when dealing with anything old that suddenly stopped working....
https://en.wikipedia.org/wiki/Capacitor_plague

Depends on the type of capacitor but if they are talking chemicals then I would think they mean wet type electrolytic capacitors and the chemicals are the electrolyte. Normally heat is bad news for electrolytics as it 'dries out' the electrolyte (they usually swell with excessive heat). So I can't think why heat would improve their performance paricularly. The problem with electrolytics is usually a long term period without being powered up and it is common to revive this by re-application of voltage, not by applying heat.However, replacement is the proper course of action but not possible on a potted module like the BB system control module. My BB 400/4 potted electronics module was on the bike when I bought it 35 years ago (and it was a good few years old then my the looks of it) , so if they do contain electrolytic caps then I consider that bad news and think it's time to ditch it and go back to the good old points type 'Kettering' ignition system that Mr. Honda provided.

[Drew400]

Thank you again. All advice gratefully received. Cheers, D.