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Discussion Starter · #1 ·
I must be old school.. A mechanic at the shop I go to noticed I shut off my fuel valve when I droped off my bike.
He says using the shut off valve is old school on the newer bikes the fuel shut off valve has a thin vacuum operated diaphragm that turns off the fuel once the engine is cut off and if the valve is used it can wear out the diaphagm and possibly leave you stranded.
I seen the vacuum hose and figured it was a nice safety feature but never heard this before about wearing out.
Whats everyone else"s opinion on this ?
 

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my opinion. I went to same school as you. I took vacuum operated valve off and put on old school type. still turn it off and on every time I ride.

old habits die hard.
 

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I do the same thing with the petcock. Turn it off. I still have the stock vacuum one on the bike. I haven't heard of very many failures once HD got past the 1st year or so. Just for your own info. If the diaphragm does get damaged, you just have to take the back of the petcock off, put the spring on the other side of the diaphragm, and close it back up. This in effect, does away with no vacuum shutting off gas flow. Could be used on the road for a quick fix.
 

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Great tips ,,,, Thanks.
One question though, is the mechanical valve body AFTER or before the diaphram?????
If the mechanical valve is before the diaphram, it would make tank drains easier by removing the diaphram and allowing flow out the petcock.
Thanks.
 

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Just switching the spring around would accomplish that. I've never had to do it myself. I watched a friend back in 95, move the spring on his in the middle of nowhere Wyoming but didn't pay that much attention.

I just use a MityVac to apply a little vacuum to the vacuum hose nipple on the petcock to drain a tank thru the petcock. Only takes a minute to hook the MityVac up, put a drain hose on the petcock and start draining.
 

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Discussion Starter · #6 ·
Thanks for the tips Ed Y.. I'm glad no one posted any problems. And its good to know what else to check incase we ever get in a problem where there's no fuel at the carb.
Besides the valve being off. "dunn that ..LOL"
 

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I turn mine off, I also turn the kill switch off. If I remember right the owners manual for my bike says to turn the gas off, its carbed, I think on the injected bikes you don't have to.
 

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I always turn mine off. Good call on the owners manual, just checked mine (2000), and is says to turn it off any time the engine isn't running to prevent flooding.

Had a POS Yamaha when I was a kid that leaked all the way down into the points, and blew the side cover off when I started it up. Cool story, but sucked at the time.
 

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I have heard of bike getting stranded due to the vacuum fail. Is this a complete "work, or not work" or can this cause a performance issue without completely shutting down?
 

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A partial fail or full fail can happen, also a vacuum leak on a full fail.. Less or no fuel in fails. Its an add on for the guys too busy to turn the valve on and off. You know Mr big from enormous enterprises type.
 
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