I've been reading that a lot of people have had success eliminating the vacuum petcock. I've been searching but I haven't found details. How does the stock vacuum petcock work exactly? Which petcock would I use to eliminate the vacuum function? What would be the benefit of this? Thanks in advance

 

Here is the best picture I could find. You can see where the vacuum from your carb essentially pulls on the diaphragm and allows the fuel to pass through.

 

And when the vacuum isn't there (shut the bike off), the spring closes the diaphragm to stop the fuel.

 

Benefits would propably be only to bypass a malfunctioning vacu-valve. By doing this you risk flooding the carbs or otherwise leaking fuel when stopped. I for one never remember to re-open the valve if for some reason I´ve turned it shut so I just let it be always open and rely on the vacuum valve to do it`s job.

To more precisely answer the question, that vacuum hose is attached into the cylinder block (cyl 1 if im not wrong) that sucks a vacuum into the hose when cranked thus opening the valve and letting gas into the carbs until the engine is stopped, the vacuum disappears and the spring shuts the valve.

 

Thanks guys after more hours of searching I found this:

http://www.valkyrieforum.com/bbs/ind...?topic=37577.0

Great info in here as well for anyone else who needs it

 

Why exactly do people want to eliminate the vacuum petcock? Just curious.

It's not really a good idea unless the petcock has failed, like Mattson said if the carbs leak you risk flooding and locking the engine. But to answer your Q, the f3 petcock is not vacuum operated and will work on the f2.

 

People do a number of things to their pet-****. me being one of those people. first I noticed the putter after removing the gas tank to replace my air filter. I checked all the hoses thought it was good when I noticed every time I parked it i could smell the strong odor of gas.. when I looked under me bike I noticed fuel leaking from my pet-****. the diaphragm was ripped in it and was leaking gas out of the pressure bleed-off hole at the base of the petcock. first i bought a new petcock that had no bleed-off hole thinking that it would work. but found out a week later that without the hole the engine vacuum ripped another hole in the diaphragm and this time, because there was no pressure bleed-off hole, the vacuum line was sucking gas directly into the #1 cylinder completely by-passing the carbs all together. I never did the gravity-fed trick just because a seizure of the engine is never worth 42 bucks. the f2's are over 12 years old, the stock petcocks went for a good run. I found out from experiance that just doing a stock rebuild of the petcock is your best guess. you might go through them once every 2-3 years but that's just because the gas nowwa days just eats them up.. still the performance and lack of a serious risk is worth it far mor than any other idea.