Son came round this morning for a ride out - I took the GF and he my early vee twin. I lent him my GF when we got back for comparison.
As he said, shame about the vibration, and I agree. Handling is beyond reproach and the engine very sweet since I repaired the magneto (cb end bearing had spun in the casing, wearing the recess until the cb was floating about in the cam ring. Dunno how it ran).
But it still vibrates, which is quite irritating. Smooth up to 40mph, but increasingly unpleasant after that. When I fitted the new conrods I re-balanced the crank to suit, making the balance factor adjustable at the same time. Tried factors between BSA's and SRM's recommendations, but little difference. Rev it up on the centre stand and it rapidly 'walks' backwards. Typical of // twins unfortunately.
All three of my vee twins are smooth. The Firestorm perfectly smooth from tickover to 9,000, my 800cc vee very smooth except for a tingle around 4,000 which is gone again by 4,500 - and the 1,000cc vee smooth all the way. Rev the latter up to 7,000 on its stand and it doesn't move.
Guess instead of creating vee number three I should have made another crank / cam for the GF. Offset of 75* (edit - might be a degree or so out, working from memory) was recommended by the maestro Phil Irving, but no magneto would cope with that angle, so my compromise would have been 60*.
Might do it yet, if the reaper stays away long enough ......
