How do you remove fuel petcock to access filter screen?

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onanysunday

onanysunday

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Apr 21, 2011
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St. Paul
Today I had to drain stale gas from a black 66cc gas tank. I removed the fuel line from the carb and held it over a gas can. When I turned on the brass petcock, no fuel came out. There was plenty of gas in the tank. I turned the petcock all the way open and around, trying to find a sweet spot, none was there. I tried this with the gas cap on and off with the same results. I ended up siphoning fuel with my mouth and a rubber hose. I've heard there is a screen filter on the inside of these petcocks that are tiny to begin with and probably also clogged. My plan is to remove this bottleneck entirely by removing the screen and replacing with an inline visu-filter.

How do you remove the petcock from the tank? How exactly is the petcock attached to the inside of the tank? Those little moist pink gaskets look pretty fragile, is it possible to re-attach them later on without breaking them? How do I do this?

How difficult is it to do the 1/8" NPT petcock, is this advised or should I stay with the original setup? I've never worked on these before.
 
onanysunday

onanysunday

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Apr 21, 2011
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St. Paul
Ok, it must have a locknut fused to the inside of the tank or something like that. Should it all come out in one piece together including the screen? Doesn't sound too difficult. I'm just worried that my gaskets will be in pieces afterwards or will start leaking. How do you get new gaskets for these things? Thanks for your help.
 
timboellner

timboellner

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Apr 1, 2009
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Towson Maryland
Not only ditch the screen filter, ditch the whole petcock.
Once you pull out the filter on the petcock the crud from the tank goes into the petcock.
If you've ever taken the petcock apart you'll notice that the passageway for the fuel to
go through is so tiny that any junk from the tank will now clog the petcock.

The only good solution is to get a decent petcock like sickbike parts sells or equivalent
elsewhere. The bore size inside the good ones will allow any tiny tank crud to pass through it and then onto your inline aftermarket fuel filter.

Another thing I've found is the stock fuel valve is so restrictive that long extended wide open throttle runs can eventually starve the float bowl in the carb.

Just my 2 cents worth

TiM
 
onanysunday

onanysunday

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Apr 21, 2011
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St. Paul
Can I just slap on another petcock that will fit the threads in the gas tank but will have a larger ID? Is drilling required? What size would this be? I am trying to avoid drilling or modifying. It would be great if I could just screw it in when I get the new part and not have to take out the old one first to measure it..My bike still works for the most part with a minor fuel starvation problem at top speed so I'd like to keep running it with a full tank and a partially clogged filter until I get my new petcock.

What size/ part number fuel petcock would you all recommend for 66cc black chinese gas tank?
 
onanysunday

onanysunday

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Apr 21, 2011
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St. Paul
Thanks guys - I just placed an order for a fuel valve from sick bike parts. Problem solved. Do I need to wait for the sealant to dry or harden before I refill the tank?
 
onanysunday

onanysunday

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Apr 21, 2011
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St. Paul
I just received my fuel petcock but it required a little modification I wasn't expecting. After I initially installed it I realized it is about twice as long as the original fuel valve! My dellorto carb fuel inlet is on the opposite side of the gas tank fuel valve. This extreme right angle covering a short distance in close quarters causes a large kink in the fuel line. I wanted to keep my fuel line as short as possible so I disconnected the valve and cut the ribbed brass piece in half with a dremel cutting bit. I'm not sure why this the brass piece on this valve has to be so long with 5 or 6 securing ribs! That's overkill - it can easily be halved and you still have more than enough surface area to attach the fuel line, with or without a hose clamp. Live and learn I guess. Now it's done and I'm glad I was able to get this valve to work. It's MUCH better than stock. After I took off the old valve I noticed the screen was completely clean. When I opened the valve in all directions and blew through it I was amazed to find that the flow was completely blocked.
 
Pablo

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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Duvall, WA PNW
www.sickbikeparts.com
onanysunday said:
I just received my fuel petcock but it required a little modification I wasn't expecting. After I initially installed it I realized it is about twice as long as the original fuel valve! My dellorto carb fuel inlet is on the opposite side of the gas tank fuel valve. This extreme right angle covering a short distance in close quarters causes a large kink in the fuel line. I wanted to keep my fuel line as short as possible so I disconnected the valve and cut the ribbed brass piece in half with a dremel cutting bit. I'm not sure why this the brass piece on this valve has to be so long with 5 or 6 securing ribs! That's overkill - it can easily be halved and you still have more than enough surface area to attach the fuel line, with or without a hose clamp. Live and learn I guess. Now it's done and I'm glad I was able to get this valve to work. It's MUCH better than stock. After I took off the old valve I noticed the screen was completely clean. When I opened the valve in all directions and blew through it I was amazed to find that the flow was completely blocked.
Click to expand...
It's just the way the barbed fitting comes from the factory. Most people don't have clearance issues so it's not a huge issue, but some do and have done exactly what you did with no issue. THANKS!!!!
 
onanysunday

onanysunday

New Member
Apr 21, 2011
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St. Paul
Tinkering is part of the fun of working on bikes to get them just the way we want - it's part of the fun. I couldn't be happier with the quality on this fuel valve and the exceptional customer service and laser fast shipping of sickbikeparts. I received my order in only two days from all the way across the country! I highly recommend them. Thank you Pablo.

Also, is it normal for the barb fitting not to screw all the way into the fuel valve? I tried tightening it up a bit to shorten the overall length of the valve but it was rock tight with half the threads still exposed. I imagine this is probably the tapered thread reaching its limit? Thanks.
 
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