Won't start.

[daz]

Steve, that's wonderful! Think how good we're all going to feel once you get this thing figured out and running again! Who needs a stinking MG?

Seriously, in the morning try it with the front off like the wise man suggested. You're so close!

[SteveD]

Well, I've got nuthin'. It still just cranks over without starting. Normally this bike fires up immediately. It's usually a very strong starter.

Today:
-neg terminal off/front cover off. edit: neg back on...Attempt to start. Didn't.
Jiggled ICU wires. No start.
Swapped ignition canister connectors. No start.
Replaced aftermarker Red Centre canister with known good oem unit. No start.
Replaced ICU with previous one. No start.

Inspection. Connectors all look clean. All looks as it should.

Battery back on a charge. I might need a new one I expect. It's 6 years of age and it now seems weak after a few attempts at cranking.
The other day it was 12.61 after a short 3 hours on full charge and went to 10.1 when cranking. 12.51 immediately thereafter just the one test attempt.

I'm still not convinced it's not the carbs though.

Off to work shortly.

[Major Softie]

I know I could go back and look, but:

have you tried starting fluid (ether) shot in through the carb throats? If it doesn't start with that, you KNOW it's electrical.

[ME 109]

I know I could go back and look, but:

have you tried starting fluid (ether) shot in through the carb throats? If it doesn't start with that, you KNOW it's electrical.

?

[SteveD]

A few days back I squirted some petrol into the spark hole. No start. 5 mls each side. Enough?

edit: however, just going back thru the thread reviewing the sequence...Duane asked if I had added petrol to the combustion chamber. Dean Lear had also suggested this and I had tried it, but it didn't work. However, not long after that was when I took the front cover off and disconnected/reconnected the canister plug and it started. I'm now wondering if it was the fuel doing it's job, just a while later

Fwiw I installed a mottobat tonight (thanks Ian, aka equipo5). It read 13v before I put it on the bike. Mine was at 12.65v. Both had the same result. Neither worked. I'll drop it off tomorrow after work.

[Duane Ausherman]

When it fails to start, are you able to remove a plug and check the color of the spark? I am getting the feeling that you have an ignition problem.

[SteveD]

When it fails to start, are you able to remove a plug and check the color of the spark? I am getting the feeling that you have an ignition problem.

I tested the plugs firmly held against the cylinder, in the dark. Bright blue spark.

I'm just back from work. Will get back in there to put everything back to scratch and start the process again.

[Duane Ausherman]

Steve, when I am in this situation, it turns out that I took something for granted and never tested it. Nearly always when you find it, it will be obvious and not something small and hard to notice. Good luck.

[blitz]

I'll add my $0.02. After 30 years, the gaskets in the petcocks of my bike swelled up (ethanol?) and blocked the fuel passages. If it sat for a while, it would slowly fill the float bowl, so it looked like it was receiving fuel, but not enough to run well. eventually, it wouldn't start. Taking the carbs apart, they were perfectly clean. Might be worth checking fuel flow.

I also had an issue this fall with my boyer ignition. I had the power wire fail just inside the insulation for the fuel holder. The bike would run up to about 4K RPM, when it fell on its face. Turns out the wire would resonate at 4K, separate, and kill the ignition. That took about 2 hours to find on the roadside.

I am with Duane. Start over, check every subsystem from beginning to end. Assume nothing.

[SteveD]

Fuel flows easily from the taps and if the bowls are removed it flows well there too once the tap is open.

Well dare I go there again? It started.
This is what I did tonight.
Firstly I charged the battery to 13v.
I put the red centre ignition back on. I cleaned and tidied all the wiring on the front. The three prong wire from alternator to diode board felt brittle. The white wire had an open, clean but minor cut in the insulation. I can't see where it would contact with anything. I taped it over.

I checked the throttle position and screwed it in a quarter turn.

Then I started the bike, no choke, throttle closed, then just with the tension taken out of the cables and it started strongly. It was 18C in the shed. The bike also started using the backup cable/hes connector on the ignition.

So, front cover back on. It started again. Remember though, this is what it did the other day too, so the real test for me will be in the morning. If it starts, I'll take it for a spin and see how it goes...the spin will be local only.

Thanks for your help & patience so far.