poor acceleration

[kenymact]

Ok....mates xt 600...1997 has very poor acceleration....we swapped bikes and the difference is very very noticeable....we pulled the carbs off and synched the secondary carb with primary as I did on mine but the poor acceleration remained unchanged, its not blowing smoke and done 50,000 kms and runs and starts easily....just poor access....its has that black box air chamber on the engine side of the cabs which my xt doesn't have....I think its a 3tb model specific item......anyhoo...any help is welcome to find the poor accel problem....would a pin holed diaphragm cause poor accel?.....will check timing next too but not alto to adjust there but its one less thing eh....cheers