IMHO ... Don't use those baffles/venturi/snorkels! You don't need them, and they restrict the flow of air into the carbs. I might be about to tell you stuff you know, but ... In the carbs, which should be dismantled and cleaned, check the main jets, if they're not marked '260' then get a pair from Amal that are, and fit those. Replace the needle jets anyway, unless you already did, they will be worn. Check that the needles have four rings lightly etched/ground into their top segments, if not get a pair that do, normally the needle clips sit in the middle position. The slides are probably worn, assuming the carb bodies are ok I'd recommend replacing the slides with hard anodised items from Amal. Take the air screws out and probe the pilot jets with a 1/16" or 0.4mm drill or wire, I've got a drill bit secured in a WD40 spray tube, but there are other ways, e.g. ebay item 222564782471. Then spray the pilot circuit thoroughly to remove any debris. Does the bike have the original 'bean can' silencers? I've seen that they're not believed to be restrictive. The 'peashooters' sound much nicer though, they're 'straight through' but not deafeningly so. Also check the fuel heights –
Bushman has almost everything you'd want to know about those carbs.
About the slides, my bike had a narrow but deep flat spot with the throttle open just a crack, I fixed it by swapping the standard size 3½ slides for size 3s, and since doing all this myself this summer my bike's better than it's been in 20 years of ownership, thanks to
a lot of patient support on this forum – but of course YMMV. Good luck, and HTH!
