Vacuum petcock?

[Guest]

My gs550 has this vacuum activated petcock. I've never had one of these on a bike. What's the benefit of these? It's a pain in the ass to hook up.. Can I switch out to a traditional gravity petcock? Or do these CV carbs need this?

[gsrick]

My gs550 has this vacuum activated petcock. I've never had one of these on a bike. What's the benefit of these? It's a pain in the ass to hook up.. Can I switch out to a traditional gravity petcock? Or do these CV carbs need this?

You can use whatever kind you want, but the vacuum type is forgiving because you don't have to remember to shut it off. It's also not hard to mount. One fuel line and a vacuum line. Why is it a pain? Big hose to the carbs between 2-3 and small hose to a vacuum port on the intake side of 2.

[aclaytonb]

The vacuum petcock made this the first carb'ed bike that hasn't died on me because I forgot to turn the fuel on.

[gsrick]

The vacuum petcock made this the first carb'ed bike that hasn't died on me because I forgot to turn the fuel on.

Good point.

[Steve]

My gs550 has this vacuum activated petcock. I've never had one of these on a bike. What's the benefit of these? It's a pain in the ass to hook up.. Can I switch out to a traditional gravity petcock? Or do these CV carbs need this?

OK, let's assume that it IS a "pain in the ass to hook up" and look at some numbers.

1. How many times a year do you plan on having to "hook it up"? If the bike is running right (assuming you have done all your maintenance), you should only have to do it every 3000 miles or so, when you adjust the valves. If you don't ride that much in a year, you will be playing with the petcock about ONCE every two years.

2. How often will you go for a ride? Does not matter the length, just how many times will you throw a leg over it and head out the driveway? If you ride to work, that will be twice a day (there and back) for 10 trips a week. If you do any kind of a 'fun' ride over the weekend, you might be gone long enough to stop somewhere for lunch, that will essentially be two rides (because you will have to turn the petcock ON and OFF). You might get into 12-15 rides per week. I know your weather isn't perfect, but 12 rides per week for four months is 196 rides. Multiply that by TWO, because you have to turn the petcock ON, and later turn it OFF, you will be fumbling for that little lever almost 400 times. Next year will be another 400 times, for a total of 800 times.

I refer you back to point #1, where you have your little "pain in the ass" moment ONCE every two years.

Maybe your memory is better than mine, but I don't mind letting the engine vacuum turn the gas on and off for me.

.

[APmech]

On the older style carbs do you connect the line to the same place on the carbs? If so what is the other nipple on the other side for?

[aclaytonb]

The other nipples on the carbs are vent lines. I believe the consensus is to leave those uncovered to prevent a fuel shortage. I found no difference in leaving them open or adding the vent lines.

[Gorminrider]

My gs550 has this vacuum activated petcock. I've never had one of these on a bike. What's the benefit of these? It's a pain in the ass to hook up.. Can I switch out to a traditional gravity petcock? Or do these CV carbs need this?

I'd keep the vacuum too, if it works. However,as said already you can put a simple one on... IF you can find one to match your tank's outlet or otherwise haywire it on there...

IF you are NOT going to use the vacuum type, and you do get rid of it entirely, be sure to plug the vacuum nipple at the carb...or simpler, leave the hose attached at carb and plug IT.

But, really, if you want a manual tap, just use the original! just turn it to Prime for "gas on" and anywhere else for "off" . You can leave the vacuum hose connected or not (if not, I say again- plug it!)