Hi y'all, got the cb400 wheel fitted and went for a test ride. What with the larger tyre and 35 tooth sprocket the gearing was too high. 50mph in second, 65mph in third at around 4750 rpm and never got near 80mph in fourth.
At more moderate speeds the lack of cushioning made for very noticeable vibration throughout the whole bike, and town riding wasn't as pleasant. I've already put it back to standard.
When cleaning up the brake drum I found it had stated to crack so wasn't going to chance a longer term test nor spend money on a range of sprockets or tyres to find an optimum. .
Should anyone else have a go then go for a wheel with plenty of drive cushioning like the Enfield and check it before doing too much work.
Looks like its back to plan B with welding a 19 tooth sprocket onto an 18 tooth centre.
Cheers, Shappers.