i've got the 66cc starfire kit with the NT carb. the carb has the secondary fuel shut-off on the inlet banjo.
it always seemed to me to be a fuel starvation problem when it would bog, speed up, bog, spee... you know, the same problem all of you have, or had.
i was thinking of re-drilling the jet, but from past experiences with cars, bikes, untied shoelaces, etc, i started at the beginning, and looked for the simple solution first. if it's starving for fuel, why?
the secondary fuel shut-off on the carb is a simple design, you twist the plastic lever off, fuel stops. twist it on, the fuel flows.
or does it?
when the fuel enters the inlet, it basically hits a wall. when the fuel's off, it stops at that wall.
when the fuel's on, it hits that wall, notices there's another way out, and goes around it, back on track into the inlet, and then into the carb.
in other words, the fuel has to make a detour on it's way into the carb, because of that fuel shut off valve. it goes like this:_____ ^_______
the "^" is where the shut-off switch is. there's a little square rubber gasket in there with 4 holes, 2 of which don't work, and 2 which get closed off when the valve is closed.
to make this simple-er, the gas isn't going straight to the carb, it's trying to squeeze through some holes in a gasket.
so, i got a drill bit the same size as the inlet hole, drilled it straight through, bypassing the shut-off valve, and now the gas flows in a straight line on it's way to the carb. the valve just sits there useless, but there's one on the tank petcock anyway, so who cares about that stupid valve.
no more bogging, better idle, and i didn't have to go crazy with the jetting.
i don't have pictures, because i just didn't care enough to take any of a hole i drilled.
if you don't have the NT carb with the fuel shut off, and you're bogging, hey, sorry about that. good luck (smiley face)
it always seemed to me to be a fuel starvation problem when it would bog, speed up, bog, spee... you know, the same problem all of you have, or had.
i was thinking of re-drilling the jet, but from past experiences with cars, bikes, untied shoelaces, etc, i started at the beginning, and looked for the simple solution first. if it's starving for fuel, why?
the secondary fuel shut-off on the carb is a simple design, you twist the plastic lever off, fuel stops. twist it on, the fuel flows.
or does it?
when the fuel enters the inlet, it basically hits a wall. when the fuel's off, it stops at that wall.
when the fuel's on, it hits that wall, notices there's another way out, and goes around it, back on track into the inlet, and then into the carb.
in other words, the fuel has to make a detour on it's way into the carb, because of that fuel shut off valve. it goes like this:_____ ^_______
the "^" is where the shut-off switch is. there's a little square rubber gasket in there with 4 holes, 2 of which don't work, and 2 which get closed off when the valve is closed.
to make this simple-er, the gas isn't going straight to the carb, it's trying to squeeze through some holes in a gasket.
so, i got a drill bit the same size as the inlet hole, drilled it straight through, bypassing the shut-off valve, and now the gas flows in a straight line on it's way to the carb. the valve just sits there useless, but there's one on the tank petcock anyway, so who cares about that stupid valve.
no more bogging, better idle, and i didn't have to go crazy with the jetting.
i don't have pictures, because i just didn't care enough to take any of a hole i drilled.
if you don't have the NT carb with the fuel shut off, and you're bogging, hey, sorry about that. good luck (smiley face)
