pete75 wrote:I'm pretty sure it was the wheels. A girlfriend had the previous model CB250 with wire wheels and that was ok in cross winds.
if the mudguards were similar and the steering geometry was the same then it might well have been. But a relatively small change in fork offset can make a much larger difference in the turning windage than you would ever be likely to get from the difference in spokes.(*) (unless they were somehow acting like wings in a crosswind....?)
IIRC (and I'm really dredging the old memory banks here) the steering geometry of the 400N model was almost identical to the 250N. Both the 400N and the 250N models were much heavier bikes than the predecessor models and they may well have made the steering lighter (more fork offset = less trail) than the predecessor models for the reasons I previously noted. [I had a '87 CB350S and that was no good in crosswinds either despite unexceptional four-spoke wheels. It had very similar steering, weight etc as a CB400N...]
(*) for example if you have a wheel of 24" rolling diameter, then a 3" fork offset is enough to put ~2/3rds of the wheel area ahead of the steering axis. This will make for a lot of turning windage regardless of the spokes used.
The above is relevant to the discussion about side wind stability; for example it is obvious that a bar bag is going to be a bit like the rudder on a boat sailing backwards but folk automatically suppose that if their low-rider panniers are more or less centred on the front wheel they can't contribute much to side windage; nothing could be further from the truth. Panniers ought to be set so that they are centred on the steering axis to avoid turning windage effects, i.e. they should be set backwards/downwards by the same amount as (or a little more than) the fork offset.