hey there levin!! ive got a v1s too but when i break inn the engine i didnt have any problems wid it. Have you adjust the idle needle? or how about the fuel pin have u adjust that? or the fuel hose if you using the standard thats may be your prblem cause their a bit small..you have to get a bigger fuel hose i think its 1mm so that the fuel can manage to go thru your engine.. When you pulling the pullstart have you notice the fuel goin to the fuel hoseline??