Classic Triumph Bonneville

[JackyJoll]

Only other thing I can think to try is hot wiring it to rule out the switch/key

As an expert engineer, you don’t need me to tell you to connect the ignition directly to + and - on a known good battery, before bothering Boyer with stuff they’ve heard a thousand times before from losers with half-crimped terminals and miles of insulating tape.

[Mr. Dazzle]

Only other thing I can think to try is hot wiring it to rule out the switch/key

As an expert engineer, you don’t need me to tell you to connect the ignition directly to + and - on a known good battery, before bothering Boyer with stuff they’ve heard a thousand times before from losers with half-crimped terminals and miles of insulating tape.

Well the box has it's own "dedicated" supply to/from the battery and I read ~13V right up next to the box (i.e. in the terminals which actually go into the box). I did try hotwiring in the end, but it makes no odds. The switch is fucking noddy, it's just three wires All you have to do to hotwire this bike is pull the rubber sheath off, unplug two wires on the switch and short them together Tried it anyway but to no avail.

I think I just have to go back to mango's comment, which is actually my comment. Dodgy earth somewhere in my 50 year old loom with 35 year old manually crimped Halfords terminals. There're only about 4 wires in the bike anyway and I've checked three and a half of them

Disaster has struck now anyway! Last time I took a spark plug out half of a single turn of thread from the head came with it. I'm usually pretty religious with copper greasing the threads 'cause I know metalurgy ain't Triumph's strong point, I'm also not actually doing the plugs up 'fully' 9 times out of 10 in my invesitgations here...just enough to keep spiders from nesting in the cylinders while I go away and do something else. EIther way, my right spark plug hole is now very much on the iffy side.

I could fix it in situ maybe but I've been wanting to take the head off anyway. The exhaust rocker box leaks like a fucking seive, so clearly something is "up" with the gasket on it.

I suspect I'll end up doing some rewiring while it's apart and/or maybe getting a new box. Potentially new coils too since they're actually really cheap! Way cheaper than a box.

[Taipan]

Is it worth investing in a new loom?

[Mr. Dazzle]

Is it worth investing in a new loom?

Yeah that thought has occured TBF.

It's 50/50 whether I'd get a new one, or just build one from scratch. The bike - and the location of various electrical bits - is pretty non-standard. The only electrics it has is the ignition, the head/brake lamps and the oil pressure warning and 2 out 3 are non-standard.

[JackyJoll]

Dodgy earth somewhere in my 50 year old loom

You’re only half-hotwiring the Boyer if you’re not connecting it directly to both sides of the battery.

[JackyJoll]

With a similar-ish (Wassell) ignition system, I’m having good success with a super-cheap Chinese 12V dual coil.

This sort of thing.

https://www.ebay.co.uk/itm/402989834964 ... media=COPY

[Mr. Dazzle]

Genuine Lucas coils are like 20 quid I think?

Not sure if being genuine Lucas is a good or bad thing

[JackyJoll]

Yeah, it is pointing to a failure under load. I'd definitely get on the blower to Boyer, as that seems to be the only common failure point. Something in the black box is getting all wheezy and asthmatic and can only manage short bursts (technical summary)...

That makes perfect sense. The only caution is that it isn’t usually the black box to blame, when the ignition starts acting up.

[JackyJoll]

Genuine Lucas coils are like 20 quid I think?

Not sure if being genuine Lucas is a good or bad thing

Genuine Lucas coils are cheap Chinese coils with Lucas written on them. So they should be fine!

I’m happier with resin-filled than oil-filled coils, but that’s not important right now.

[Mr. Dazzle]

Much as black boxes tend to get criticism (see above, from me!) I do have to agree they're usually not the culprit. Solid State electronics are pretty robust, no moving parts and all that.

Doesn't mean a soldered joint hasn't cracked or something like, but look at the state of the wiring in my pics

I've mentioned this before, but that wiring was done by my FiL (RAF engine tech) and uncle (RAF engine tech and then automotive electrician). Never buy a mechanic's car right?

[JackyJoll]

:

I've mentioned this before, but that wiring was done by my FiL (RAF engine tech) and uncle (RAF engine tech and then automotive electrician). Never buy a mechanic's car right?

He wasn’t at his work when he lashed-up the bike!

[mangocrazy]

If the bike is hors de combat due to other issues, I'd bite the bullet and make up a new loom. On a modern bike that would be a nightmare, but on your Trumpet it should be fairly straightforward. Use good thinwall cable of a gauge at least one size larger than OE and a quality crimping tool and you should be good to go. Vehicle Wiring Products should have all the bits you need.

Then if it still doesn't go, give the black box a good coat of looking at...

[Mr. Dazzle]

Yeah but you're not considering the fact I fucking hate wires

[mangocrazy]

Yeah but you're not considering the fact I fucking hate wires

I based my reply on the fact that it would be you doing it, not me...

Although at some point in the future I may need to make up a replacement loom for my 1980 Lancia Beta. Now that is a scary thought...

[Mr. Dazzle]

Realistically there are only about 5 or 6 wires the bike actually needs. And even after that there are only a half dozen more anyway. No indicators, no horn, no kill switch, no idiot lights, no ECU etc.

S'only really the sparks and the charging circuit to worry about. Oil pressure is probably a wise one to have as well. Oh and brakes I suppose!

[JackyJoll]

If the bike is hors de combat due to other issues, I'd bite the bullet and make up a new loom. On a modern bike that would be a nightmare, but on your Trumpet it should be fairly straightforward. Use good thinwall cable of a gauge at least one size larger than OE and a quality crimping tool and you should be good to go. Vehicle Wiring Products should have all the bits you need.

Then if it still doesn't go, give the black box a good coat of looking at...

Big fat wires are worthwhile in the charging and headlight circuit (a circuit includes the return!).

I’ve gone for thinner wires for LED rear light and indicators and electronic instruments.

[JackyJoll]

Realistically there are only about 5 or 6 wires the bike actually needs. And even after that there are only a half dozen more anyway. No indicators, no horn, no kill switch, no idiot lights, no ECU etc.

S'only really the sparks and the charging circuit to worry about. Oil pressure is probably a wise one to have as well. Oh and brakes I suppose!

I may already have said this. Most, but not all, late Unit timing covers have NPTS (parallel) threads in the hole where the oil light sender goes.

[ChrisW]

Yeah but you're not considering the fact I fucking hate wires

I'm with you on that, but a bit of pain re-wiring it will probably mean you get to spend less time with wires in the long run.

[Mr. Dazzle]

Been pondering this...I don't think its all that much effort to wire the ignition completely separate from the rest of the bike. "Rest of" really only being lights and a few minor things. So just chop out and/or leave alone the current ignition wiring and make a brand new system just for that.

The bit I really don't want to do is get among the shitty rats nest in the fairing

As it currently stands the lights work regardless of where the key is anyway, so I'm already half way there

[Le_Fromage_Grande]

Yeah but you're not considering the fact I fucking hate wires

I based my reply on the fact that it would be you doing it, not me...

Although at some point in the future I may need to make up a replacement loom for my 1980 Lancia Beta. Now that is a scary thought...

Lancia Beta, oh dear, I hope you know a good welder