Hi All,
I have a 2007 VTX 1300 S which I bought a few months back and have been doing some tinkering. The bike is almost 'done' (you know that's a lie...), but the last remaining issue seems to be a starting problem.
Specs first (as far as I know, not much info from the PO): Cobra slip-ons, stock airbox with K&N filter, I did the PAIR mod, new plugs and fluid (Mobil One 4T 10W-40 oil), around 30K kms (18,5k miles) on the clock, new Yuasa battery, A/F screw out 2,5 turns, no SCAR mod (as far as I know).
It goes very well in general, but it can be a real pain to start, sometimes it doesn't start at all. I live in Australia, so a cold day here is ~10C (50F for our US brethren) with a warm day around 105F+. I finally tracked the problem down to fuel supply, I think, and I suspect it's the petcock vacuum fuel valve, although it seems to work when I checked it. Vacuum lines seem OK.
My question is this: the vacuum necessary to actuate the petcock, does it have to be a mere pressure reduction, or an ongoing suction (if that makes sense, barring the TWSS jokes). In other words, when I apply suction with a tube to activate the valve, it takes continuous suction, i.e. breathing in continuously, for fuel to flow. I ask, because a mechanic on YouTube mentions you can apply a vacuum and clamp the line to keep the petcock open, which is not the case with mine.
I've already ordered a new diaphragm for the vacuum-operated valve just in case, but I guess I'm looking for validation that that's the problem. Can you 'normally' apply vacuum to the line and clamp the line to stay open, or does it need constant suction to stay open? With the 'T' in the line between manifold and carb, and the design of the valve shown in the service manual, I'm assuming it only takes a pressure reduction to work, so my guess is the diaphragm is not 100%, but I'd really appreciate feedback from anyone that knows what I mean.
Happy to provide more info. Thanks in advance!
I have a 2007 VTX 1300 S which I bought a few months back and have been doing some tinkering. The bike is almost 'done' (you know that's a lie...), but the last remaining issue seems to be a starting problem.
Specs first (as far as I know, not much info from the PO): Cobra slip-ons, stock airbox with K&N filter, I did the PAIR mod, new plugs and fluid (Mobil One 4T 10W-40 oil), around 30K kms (18,5k miles) on the clock, new Yuasa battery, A/F screw out 2,5 turns, no SCAR mod (as far as I know).
It goes very well in general, but it can be a real pain to start, sometimes it doesn't start at all. I live in Australia, so a cold day here is ~10C (50F for our US brethren) with a warm day around 105F+. I finally tracked the problem down to fuel supply, I think, and I suspect it's the petcock vacuum fuel valve, although it seems to work when I checked it. Vacuum lines seem OK.
My question is this: the vacuum necessary to actuate the petcock, does it have to be a mere pressure reduction, or an ongoing suction (if that makes sense, barring the TWSS jokes). In other words, when I apply suction with a tube to activate the valve, it takes continuous suction, i.e. breathing in continuously, for fuel to flow. I ask, because a mechanic on YouTube mentions you can apply a vacuum and clamp the line to keep the petcock open, which is not the case with mine.
I've already ordered a new diaphragm for the vacuum-operated valve just in case, but I guess I'm looking for validation that that's the problem. Can you 'normally' apply vacuum to the line and clamp the line to stay open, or does it need constant suction to stay open? With the 'T' in the line between manifold and carb, and the design of the valve shown in the service manual, I'm assuming it only takes a pressure reduction to work, so my guess is the diaphragm is not 100%, but I'd really appreciate feedback from anyone that knows what I mean.
Happy to provide more info. Thanks in advance!