Runs rough after about 2k rpm and won't go much beyond half throttle without violently shaking, can't go more than about 40 and it's very slow, checked the points and the gap is spot on. Also had full service with cap, rotor arm, plugs and leads and a fuel filter a few months ago. Any ideas?

will it rev high if you dip the clutch?

id be looking at what you replaced suspecting something is faulty

Nope it just won't rev above about 3.5k and was driving fine before I adjusted the points gap, reckon it could be ignition timing although it went back on where it came off?

Is the idle still smooth or does it wander? If it wanders especially fast maybe an airleak.

Otherwise secondary main jet blockage or fuel pump dying are my non commital guesses tonight.

Seems to idle reasonably smoothly, only adjusted it to see if it would solve the hesitation when pulling away, it's fixed that issue but now it isn't really driveable and can't get to 40 without a lot of patience😂

Hesitation pulling away really could be airleak. Does the carb wobble if grabbed with both hands, or does spraying cold start spray around the carb base cause the engine to speed up?

The rubber base mount is one of the few weak points.

It's not the base mount as I've sprayed it all up to check it

All sorted now, turns out the gap was twice as big as it should have been causing it to misfire badly at high revs but reset it and it's all sorted now and it even drives better than before too😂