One red sparkplug

[raypond]

OK, I like this theory as well. I'll start with the easy stuff and swap the plug leads over and see what happens. Thanks for the opinions.

Cheers
ray

[Airbear]

Ray, the too-lean condition can be caused by a leaky carb-to-head sleeve.

[SteveD]

Ray, the too-lean condition can be caused by a leaky carb-to-head sleeve.

If that's the case, you might also be hearing some exhaust burbling when backing off.

[raypond]

Yep, got a little popping in the exhaust when backing off. I put it down to the balance pipe between the headers not being a tight fit. Oddly it was worse but improved when I put in a new air filter. I don't understand that.

Ray

[Major Softie]

Yep, got a little popping in the exhaust when backing off. I put it down to the balance pipe between the headers not being a tight fit. Oddly it was worse but improved when I put in a new air filter. I don't understand that.
Ray

AHA! If your dirty air filter was restrictive, then the engine would have more vacuum in the manifold, and thus would draw a larger percentage of it's air from an intake leak than after you put in a new air filter. So, that symptom actually points even stronger to an intake leak downstream of the carbs.

[raypond]

Damn fine deducing Major. I couldn't see any obvious leak but loosening things off, jiggling and re-tightening does seem to have reduced the popping in the exhaust. I'll do a few 100k and pull the plugs again and see what's happening.

Thanks again for all the input.

Cheers
Ray

[Motorhead]

Or maybe the carb balance is foo foo

I saw lots of color with my Bings when they need to be serviced