hi,

my vspec is behaving badly. it backfires when i start to accelerate past 1/2 throttle(mainly during the first few accel attempts after startup, or after a long period of only low throttle application, like in the tight and twisty stuff and then i go to accel onto the main straight) it almost seems as though its being starved of fuel?

sometimes it'll clear itself out and go fine there after, or else it will bog right down and i have to let up on the throttle to stop it dying, sometimes unsuccessfully. and it will randomly shut down when i get on the gas for a jump/ short straight. it also seems to have a lean bog just enough to hear it and feel it hesitating.

i have tried all number of needle settings and the only difference i get is that the high end adjustments have their respective affects, as you would expect. nothing i do to the low end needle affects the low range, except i can make it too lean, never rich enough though.

i have already checked compression(v good) backplate seal(fine) fuel tubing(no difference after replacing) fuel filter(fine) carby seal(fine), engine head is on tight and secure.

does anybody have an idea as to what my problem may be. i run 20% nitro and i use the head shim. it runs at around 230-260 so no dramas with the temps either.

thanks.