H1-B Failed to proceed!

[Akashi Classics]

Guys, my beautiful H1-B has blotted it’s copy book for the first time since I restored it over 25 years ago.
Took it out yesterday (nice 25c Melbourne autumn day). Started easy; settled into a steady idle; jumped on and got not much more than half a mile up the road when it rather quickly started to lose power; and died!
It would restart, idle, put it in gear, then as soon as I began to let the clutch out, it would die again.
Sometimes I could get it to rise in revs, but only for a few seconds before it would fade away to nothing.
I though of a blocked fuel cap vent, but it’s definitely not that.
The bike is basically bog standard.
It could possibly be the fuel tap diaphragm, but I’m getting more of an ‘electrics’ vibe.
Any thoughts/clues/‘I’ve had this happen too’ would be much appreciated.
Cheers from DownUnder
Jeff

[husson73]

some bad condensators perhaps as those you find now (unless you got some good old NOS) are mostly chinese junk.
But am only bet two cents on this (fuel cap vent will be the first idea but you already have it).
If it was the coils it's rather rare that the 3 went off on the same time (excepted on earlies H1 with CDI on which you got one coil for the 3).

[Akashi Classics]

Thanks JP, I didn’t think about the condensers. Good point.
I have an old school ‘tune up kit’ I’ll pull out. Fairly certain the condensers in it (if there are any) will be Japanese.

Still open to other thoughts though.

Jeff

[mraxl]

Does battery have full charge?

[Wolfie]

As Dale says above, check the Battery, otherwise..

Electrical and Ignition problems tend to just cut out instantly, no fading away like you describe..

If the Battery checks out OK, I'd be more looking towards a fuel issue.

Hope it's a quick fix Jeff

[TallyB]

I was thinking coils

[mraxl]

Coils are the last thing I would consider... but checking them is easy. A single coil would only affect one cyl and for all to be bad at the same time would be extremely unlikely.

[skub]

Fuel starvation,or fuel contamination?

Does the choke help keep it running,or kill it?

[Akashi Classics]

Thanks to everyone who responded. I was snoozing away down here while you all had your thinking caps on.

I’ll be looking at all the suggestions to sort the old girl out.
The battery will be the first thing probably, but I’ll let you know once she’s sorted.
Thanks again,
Jeff

[husson73]

Fuel starvation,or fuel contamination?

Does the choke help keep it running,or kill it?

water on the fuel?
30 years ago I rented a MZ 250 on a caraiban island.
Just remembered did same as you.

[johnnymoped]

Don't think it's the battery - when the battery gave up on my H1b it just stopped - no restart - restarted and ran perfectly with a fresh battery.

[Doctorpayday]

Hi

Have you tried running on reserve, just in case blocked fuel tap filter.

Had similar problems and eventually found no filter and brass pipe severely restricted.

Never a dull moment.

Doc