My 2001 Triumph Adventurer had a bit hesitation mid range -ordered a jet kit and all seemed well for a few days then the idle would jump up and down stripped the carbs again and cleaned everything that did not really help it which got me thinking it might be the coils?
Anyhoo removed the coils and ordered a new set but low and behold they are on serious back order so after about 10 days reinstalled old coils installed the tank now when I try to start it turns over great but as soon as I stop cranking it - it sounds like a soda bottle opening and petrol gushes out under the bike, thinking sticking floats? all suggestions welcome.
are you sure you hooked up the fuel lines correctly? Sounds almost like the vacuum line to the petcock is hooked directly to the tank?
If you haven't already done so it's about time to replace all of the fuel and vacuum lines anyway. I neglected this and a fuel line split right after I filled up on my '94 Sprint.
sticking floats or incorrectly installed floats as for original problem is there and perishing in the rubber boots between the carbs and head you may have a vacum leak
i believe Hanso is on the right track....if you get the carbs to stop leaking ang get it fired use starting fluid or brake parts aresol cleaner and spray around the rubber manifolds..if the R.P.M. changes there may be all or part of the problem
if that doesn't work bring it on over here to South Dakota and ill help ya get it running right