Weber set up

[Kevin Wood]

Also worth remembering that the ignition system is under the most duress under heavy load, so could the misfire be an ignition issue?

[Zetecinside]

If i may suggest its not the carbs but the ignition.

So, cap and leads changed. Have you checked any other ignition components?

 

[Davemk1]

4 hours ago, Zetecinside said:

If i may suggest its not the carbs but the ignition.

So, cap and leads changed. Have you checked any other ignition components?

 

I agree - my gut says it's the coil.

dave

[Andrew]

Check you haven't lost a grub screw from the underside of a carb. I've had it happen, and it allows a choke tube, or emulsion tube to rotate in the carb body. It effectively shuts off fuel under load to that barrel. Easy enough to check, have a look down the four chokes and see if the horizontal bars are symmetrical in the two carbs. (They're not absolutely horizontal, but each carb should look the same)

[Captain Colonial]

Coil certainly the easiest thing to check, easy and cheap to replace.  Can look fine and act okay at idle, but fail once warmed up under load, happened to me once, required RAC help.

[Kevin Wood]

Condensers also have a habit of working when cold and then packing up when hot. See if there are any blue/green deposits  around the points, assuming it's not got an electronic ignitor.

[Grizzlee]

On 13/04/2018 at 14:53, Grizzlee said:

Drop me a PM with your number, I'm in Warrington and would be happy to take  a look for you.

Graham

My offer still stands, I have spare coil and if I look really hard in the garage and sheds, a complete distributer including the ignition module for a CVH from a recent rebuild