Sounds like the sort of thing we did as teenagers. Is the inlet valve still standard? There are books on optimum fuelling for internal combustion engines. A 930 still seems a bit on the big side. Don't suppose it makes much difference really. My 500cc Velocette breathes happily through a 1 1/16" carb and goes really rather well. Better than my bog-standard B31 anyway.
Yep, valves are still standard, if it does not go well enough I have a “BB” barrel and head to fit to it, and which has larger valves as std. Apparently the early smaller fin engines overheat when tuned up which is why I bought these, as “insurance”.
I’ve used the small fin barrel for now as it had already been bored to suit the Yamaha piston which came with the bike. Bigger than standard Triumph T140 valves and springs can be fitted in the Large fin heads to up the power further.
If you keep going you end up with effectively a “cast iron goldie”
