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Discussion Starter #1
i was sitting around thinking about how much gas my new clark xt tank is holding down in the front that is basically going to waste. i thought about trying to relocate the petcock, or just adding a drain tube and piping it in somehow, and then i thought maybe i could somehow angle one of the fuel pickups on a petcock assembly and add an extension tube so it reaches the front of the tank. my question is will the fuel travel through the extension even if it travels at an upward angle and then makes a 90 degree turn down to the carb. is there a vacuum in the fuel system, or is it simply gravity fed?
 

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Well Harley guys have a style called Frisco style. The petcock is relocated to the rear of the tank and the front is raised to tilt it.
 

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Discussion Starter #4
went ahead and bought an extra petcock just to try this out. ended up cutting the extended part off and putting some fuel tube on it and part of a coat hanger to keep it aimed in the right direction. then I stuck the part I cut off, with the filter, on the end. I tried it out today, was able to get to about 215 miles before I switched over to the new reserve, don't know how many more miles I can get out of that yet, but so far there were no problems with it having to suck the fuel up the small angle in the tube. before the mod I usually had to switch over to reseve around 160 to 170.
 

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It should flow by gravity unless the loop is high and you run dry or low and get an air bubble in the line, like a waste trap - that would break the siphon.
 

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Maybe you need a turkey baster (tube with squeeze bulb on the end) so you can suck the gas from the front of the tank and squirt it into the back part where the petcock outflow is located. Low tech - fail proof if you try it at home and caution others not to try it because you are a professional. Just offering an alternative. BTW I'm pretty sure I have a big not easily accessible reserve with my oem xt350 tank, but have never driven it to the fumes to determine how much. Good luck. Tom
 

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Make the effort to remove all the air from your see-through fuel filter, take a short ride, and it will develop a bubble within. I've no idea from where the air comes for sure, but I'm thinking past the float needle when it opens.
 

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went ahead and bought an extra petcock just to try this out. ended up cutting the extended part off and putting some fuel tube on it and part of a coat hanger to keep it aimed in the right direction. then I stuck the part I cut off, with the filter, on the end. I tried it out today, was able to get to about 215 miles before I switched over to the new reserve, don't know how many more miles I can get out of that yet, but so far there were no problems with it having to suck the fuel up the small angle in the tube. before the mod I usually had to switch over to reseve around 160 to 170.


Any pictures danwray? I'm in the middle of a tank install myself and trying to mount the tank to get the most out of it.

thanks Josh
 

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An interesting exercise that several folks need to do is to determine how much gas we actually have available (i.e. will run out of the petcock outflow). Forget what the dealer or manual says - what really counts is how much gas will run out of the fuel petcock when the bike is setting level and upright. Its simple - just fill tank and then remove fuel line and let it drain into a fuel can and measure once it stops. Then shift to the reserve and measure what comes out then. Have the kitchen measuring cups available to get a good measurement. As I recall when I was shifting out my stock tank, I drained from the main petcock setting, and then shifted to the reserve. Unfortunately the tank was off the bike but positioned level, but as I recall I got a lot more gas out of the tank from the reserve than I expected. What? You want me to recall exactly how much?- no way - but it was a lot. I seem to recall that it was close to 3/4 of a gallon or essentially the 0.8 of the 1.8 tank. Meaning we (you) are running on a gallon of gas until we switch to reserve. With my 3.2 gallon tank, I may have as much as 1 gallon in reserve, but I have no idea how much of it is available to me because I have not done my drain and measure exercise. Cheers, Tom
 

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Discussion Starter #10
sorry man, no pics, but it's working so well I might take it apart to document it. It's actually pretty simple though, if you have some questions let me know.
 

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An interesting exercise that several folks need to do is to determine how much gas we actually have available (i.e. will run out of the petcock outflow). Forget what the dealer or manual says - what really counts is how much gas will run out of the fuel petcock when the bike is setting level and upright. Its simple - just fill tank and then remove fuel line and let it drain into a fuel can and measure once it stops. Then shift to the reserve and measure what comes out then. Have the kitchen measuring cups available to get a good measurement. As I recall when I was shifting out my stock tank, I drained from the main petcock setting, and then shifted to the reserve. Unfortunately the tank was off the bike but positioned level, but as I recall I got a lot more gas out of the tank from the reserve than I expected. What? You want me to recall exactly how much?- no way - but it was a lot. I seem to recall that it was close to 3/4 of a gallon or essentially the 0.8 of the 1.8 tank. Meaning we (you) are running on a gallon of gas until we switch to reserve. With my 3.2 gallon tank, I may have as much as 1 gallon in reserve, but I have no idea how much of it is available to me because I have not done my drain and measure exercise. Cheers, Tom


My 2 cents: I recently cleaned my petcock tubes, so I drained all the fuel out of the stock tank by the petcock on reserve, removed the petcock, drained the rest of the tank dry, and then blew it out with compressed air, so it was absolutely empty. Once I reinstalled the cleaned petcock, I filled it from my 2 gallon containing exactly 2.06 gallons according to Gas Station's digital gauge. I was frankly pretty surprised to see that my stock 1.8 gallon tank easily took the entire 2.06 gallons, and still had room for more (wasn't to the gas hole insert). <Is it allowable to "gas hole insert"?> Anyway, it made me realize we're carrying probably a quart of gas that can't be accessed by the petcock. Guessing it lives in the lower section on the right of the tank.
 

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sorry man, no pics, but it's working so well I might take it apart to document it. It's actually pretty simple though, if you have some questions let me know.


danwray - I'd be interested in trying your petcock extension method. From what I understand, you've cut off the regular fuel intake tube (not sure how else to call it) and extended it toward the lower part of the tank by connecting it back to the main part of the petcock with a rubber fuel tube. Did you have to seal the cut parts with anything or it just stuck on?



I'm also confused about how the coat hanger plays a role. Did you just use the coat hanger temporarily to guide the end of the tube into the right spot, or does it stay in the tank permanently, providing the tube with support?
 

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Discussion Starter #13
that's correct, I left about a half inch sticking out of the petcock to mount the fuel hose. I used no seal, but I did bend the edges of the cut tube out a bit to make sure it holds on to the tube. otherwise it sealed up pretty snug by itself. The coat hanger was used to ensure the new fuel pickup stays in the right place, so I simply cut it to length and put it inside the fuel tube itself and it stays in there. I found that on my tank the hole for the petcock was the perfect size for the modified tube and if you put the fuel line on so that it goes all the way down to the petcock base, the tank will also help secure the line on there.
 

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Danwray, I commend you for your creativity. However, I also recall a long ago post that said that something like 30 per cent of the tanks that were opened had the screen intake of the fuel outlet, loose, displaced, nonfunctional. What this means is there is a lot of vibration in the tank area and things that are in place today may not be after 200 miles of bouncing. This is just a warning to stay aler to problems down the road. Stuff happens. Good riding. tom
 

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Discussion Starter #15
point taken man, this is definitely still in the "experimental " phase. just putting it out there if someone else wants to try it or has any improvements.
 

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Very interesting! That's pretty creative. So you left the reserve tube as is? It will just not be used ever?



Let us know how the whole new system turns out over the next few months




that's correct, I left about a half inch sticking out of the petcock to mount the fuel hose. I used no seal, but I did bend the edges of the cut tube out a bit to make sure it holds on to the tube. otherwise it sealed up pretty snug by itself. The coat hanger was used to ensure the new fuel pickup stays in the right place, so I simply cut it to length and put it inside the fuel tube itself and it stays in there. I found that on my tank the hole for the petcock was the perfect size for the modified tube and if you put the fuel line on so that it goes all the way down to the petcock base, the tank will also help secure the line on there.
 

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Discussion Starter #17
well yes and no, the reserve is now my regular petcock position, and the new extended tube is reserve. I just have to remember that because it now is the opposite on the valve too.
 

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I'm still having trouble picturing this in my head. Any chance you'll have pictures or be making a "write up" any time soon danwray?

thanks Josh
 

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Discussion Starter #19
yeah man, I'll get some pics for you soon. Keep in mind I also went ahead and bought a new petcock to try this on, just in case I screwed up.
 

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ok, went ahead and took it out to check on it and get some pics. looks like the tube expands a bit after a while, which makes it sit even better at the petcock itself where it is between that and the tank plastic, but it made the other end a little too loose where the new intake is. so i put a fuel line clamp on that end to be safe. in doing so however, i made it impossible to load the whole thing through the small hole where the petcock goes, so i had to drain the tank and fish the line through the hole from the inside, and then connect it to the petcock before i screwed the petcock back in. a little bit more of a pain, but i'd still rather have that little filter on the end of the tube just in case. anyway, here's some pics, i hope they clear up any questions about what i've done.





 
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