Just another question or two... for now!

Do bike carbs hang off the inlet manifold, or do they need a support bracket? (I have the original connecting rubber tubes, and they seem very tough and near-as-dammit rigid).

Is there an optimum length for the branches of the manifold, or is it simply the shortest length that can be fitted in tidily? (I would like to get the carbs and filter under the bonnet, without cut-outs if possible).

Given time on a rolling road you could experiment with manifold length but in the real world I think its a case of make to fit available space? I ended up making a couple of supports to retain TBs to manifold but I used silicon hoses that tend to slip.

Try and get the end of the manifold tube machined to look the same as the head on the bike engine - this way the rubbers will hold them on really well (as well as the bike!)

Wyn

That's my plan - I'm going to use thick-wall tube so that I can machine a groove near the end, to match the ones on the carb connections.

Are you sure it's supposed to be that rigid and hard? Ooooer misses....

With the ST1100 they say the rubber degrades so if the connector is hard you need to replace it otherwise you get yucky air leaks mucking up the running....

It's got a bit of bendy-ness - not totally rigid!

ooeer indeed!

I'd say it's best to get the carbs as close to the head as possible, and use the trumpets to adjust the length of the inlet tract if necessary. It's easier that way, and the further away the carbs are from the engine the worse it'll run when cold and/or idling