Vince,
I'm running 32 mm Mk1 Concentrics with air cleaners, on my twin engine.
Pazon ignition (not a clue where it's timed), 2 plug hole heads, but only ever used single plug and decompressors (no help there then), 8.5:1 compression, Mk3 cams, and a Dunstall Decibel silencer which isn't too restrictive.
I'm using 210 main jets, I haven't done a plug chop ( as I said earlier ) but I don't think they're too far out - I'm not racing, and I've had trouble setting up with this awful new petrol, so I haven't worked on top end speed as yet, and my understanding is that concentrics only use the main jet (in anger) over 3/4 throttle.
Other settings are 107 needle jet with the needle in the top (weakest groove) and 3 1/2 slides.
I don't know how the performance is, I've been using Japanese multis for a few years, so I've forgotten what to expect from a Vin. It accellerates crisply through the rev range, will do 40 in 1st, 70 in 2nd, 90 in 3rd and so far 90 in top (2 up) comfortably without complaint, so I don't think the settings are too far out - will see when I get round to pushing it when there are no cameras or spotter planes about.
Bill is right about winding Vin motors up, I think you need to get them moving in third, to make sure the revs are still high(ish) when you change into top, perhaps they need the 5th gear for performance.
The straight through silencer is also essential for peak power. My first track day at Silverstone, I replaced a spiral baffle silencer with a straight pipe half way through the session (no other mods), and that must have given me 10% more power, it was instantly noticable, but too loud for the road.
H
ps - Just seen Dan's comment about 240 jets, I think they're bigger than I'm using (assuming I really am close with 210s) because I'm using air cleaners. 210 are the smallest jets in my box of tricks, so I probably used bigger ones on "real" petrol and bellmouths when I was a kid with a memory.
