Carby Tuning

[trev29]

Hello. First ever post. Loving this site!!  I have just spent the best part of a day n a bit, cleaning and rebuilding the carbys on my fj1200 (1988). I have hand drilled the mains the next drill bit size up, set the floats to 23mm, installed a 4psi fuel pump and a efi fuel filter (mainly to keep everything clean because the amount of tank debris in the float boals was astonshing). Set the needles on the third mark, have uni pods, a 4 to 2 exaust.... and OMG!! what a difference!  Feels like i been riding a 250 around compared to now haha. There is however some minor backfiring on decerlleration. Any pointers would be appriciated. Oh and mixture is at 2.75.  Cheers.