No one seems to remember: if the vacuum petcock has a problem, put it into PRIME. that bypasses the vacuum and now you have one that operates like an on-off petcock.

I think we're seeing the continuation of needless petcock bashing and making people fearful of them for no reason.

So many more people have had a broken chain, FLAT TIRE and many other things happen than have a petcock go out while riding. Why don't people complain about flat tires and filling the tires with foam so they don't have to stop because of a nail in the tire? I worry much more about that.

After all, I know there is the PRIME position just in case I need it.

Replaced the original fuel hoses, secured the new ones with hose clamps and took the bike out for a test run.  Twenty miles at 70-75 mph and NO fuel starvation symptoms!  It was not the petcock!

Addidas, Why are you so committed to changing peoples minds on the idea the vacuum petcock is worth keeping?  Its a part easily replaced with a different assembly with less moving parts less prone to failure?  I am not seeing why keeping the vacuum setup is worth doing, just to have it fail again later...

I wouldn't change out the petcock if it wasn't broken, but if its broke, swap to a non vacuum system.  Itll cost the same and you'll never have to fuss with it again.

ha just noticed this was a thread from last year!

The vacuum petcocks rarely fail.
Its one of those things that when one fails, the person makes a federal issue about it.
Chains fail.
Fork seals fail.
Spark plugs fail.
Tires fail.
all of those and many more things fail far more often than a vacuum petcock.
Lots of bikes have vacuum petcocks. They work. They are reliable.
In the rare time that one fails, just replace it with a new one.

Fork seals fail - yet no one talks about replacing fork seals with something else or welding the forks.

If you want to replace it with something different, then do so.
The point is that they fail so rarely (compare it to replacing for seals which everyone has to do on a regular basis) there is no reason to engineer something different.

It is so simple to simply put on a new one and not have to worry about it for another 20 years.

The truth is II have never seen one fail.
HOWEVER.... I have seen some act bad only to open them up and find sludge in them - like sludge in fuel lines or the bottom of the tank. A simple cleaning and they were back like brand new. Fuel starvation is most likely sludge clogging the lines (which can also happen with a pingle) rather than a real failure of the petcock.

Now if you rejet and change the airbox, you can have fuel delivery issues with most any gravity fed system due to a fuel demand higher than what the system is designed for. That is right out of the Haynes Motorcycle Fuel Systems book.

I hope this clarifies my stance on the vacuum petcock.

(If you check, nearly every bike these days has a vacuum fuel valve.)

My petcock never leaves the PRI position

Quote from: weedahoe on June 01, 2013, 02:27:24 PM
My petcock never leaves the PRI position

Well, let's hope you never have a sunk float or needle valve/seat failure.

Whoa...zombie thread...

Quote from: chornbe on July 22, 2016, 05:43:24 AM

Quote from: weedahoe on June 01, 2013, 02:27:24 PM
My petcock never leaves the PRI position

Well, let's hope you never have a sunk float or needle valve/seat failure.

Pretty sure I know how to build carbs and preventive maintenance so I think Im good on one not ever leaking on me.