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.

NEW PLUG YET?

+1.
Vspecs are heavy on plugs. Lasts approx 4 litres. Replace and make sure you have spares. My Vspec cost me my race on Sunday also plug issue. Other than that once you have a new plug its no problemo.

You only need the one shim in, remove the second one if thats what you mean.

check the in-tank filter to see if its clogged. check to see if your exhaust has a leak or crack. check again for air leaks around the tank and fuel tubing. check to see if u have an air leak around the bearings.

it sounds like ur fornt bearing is leaking check it out.thats what happend to me after that it ran great