Yep water is always a problem especially as it can condensate in the alloy tank but the've been stripped sonic bath and blown through - I have had a thought though, couple of years back my Triumph was misbehaving - ok when cold but would start spitting at higher speeds, then clear - tried loads of things to sort - plugs - leads- ecu and even had the head off and skimmed as a local dealer advised the head was blowing slightly. None of it made a difference - finally traced the problem to worn needle seats, two out of the three had worn oval so were screwing the mixture - So current set up has probably done 50k miles and I'm running very short filters and lots of vacumn so this may be the problem.
Not allowed to play with it tomorrow but got the all clear for 26th - so carbs off and have a look at the seats - I'll update once I've had a peak!
Cheers