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So I'm pretty new to owning and maintaining motorcycles. I've done all my own automotive maintenance so I know my way around a shop. But needless to say I feel like an idiot with this question. On the fuel petcock (which I am completely ignorant of it's operation and purpose), how do you know which direction is on? Yesterday I had the longer piece of the switch towards the "on". After riding about 2 miles the bike stalled out. So i switched to the other side "res". It ran to the gas station and I only put 1.2 gallons in. I left it towards the "res" the rest of yhe way home and it was just fine. So I wasn't out of gas. I guess my question is what is the difference (if any) between the res and on? Is it detrimental to leave it on "res" instead of "on"? Thanks guys. On a side note, I freakin love this bike. My mountain bike hasn't seen the light of day for the past three weeks!
 

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So I'm pretty new to owning and maintaining motorcycles. I've done all my own automotive maintenance so I know my way around a shop. But needless to say I feel like an idiot with this question. On the fuel petcock (which I am completely ignorant of it's operation and purpose), how do you know which direction is on? Yesterday I had the longer piece of the switch towards the "on". After riding about 2 miles the bike stalled out. So i switched to the other side "res". It ran to the gas station and I only put 1.2 gallons in. I left it towards the "res" the rest of yhe way home and it was just fine. So I wasn't out of gas. I guess my question is what is the difference (if any) between the res and on? Is it detrimental to leave it on "res" instead of "on"? Thanks guys. On a side note, I freakin love this bike. My mountain bike hasn't seen the light of day for the past three weeks!


Your petcock picks up fuel from one of two points, one higher than the other inside the tank. In the "ON" position it picks up fuel from the higher point until that fuel is exausted, then in the "reserve" it picks up fuel from the lower portion until the tank is empty.



If you leave it in the "reserve" position you'll have no advance warning that you're running short on fuel because the tank will run til it's fully empty.



Your tank only holds 1.8 gallons, so you were well into reserve territory when you left, so probably there is nothing wrong with the petcock.



If with a full tank it still won't feed fuel in the "on" position there are two possibilties with your bike: One is that the petcock is clogged on the "on" side orifice inside the petcock. The other is that the standoff tube filter inside the tank is varnished and/or clogged.



There is also a third (remote) possibility that some prior owner put a petcock from another model Yamaha on there. Almost all of them are identical except for the length of the standoff tube for the "on" position, and if they chose one that was too long it would hit reserve prematurely.



The other function of the petcock is the "off" position. Since our bikes are a "gravity feed" arrangement in the event of a worn float seat or if the float gets knocked out adjustment it will flood the carb, then the airbox and eventually fill the crankcase with gas. Any time you park the bike overnight or for any extended period you should turn the petcock "off".
 

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I can't remember where the on and off labels are off hand, but I know that the long part of the switch pointed down is "On". The long part of the switch pointed up is "Reserve".



If you leave it in the "On" position, and then you run out of gas, you switch it to "Reserve" and ride it to the gas station. If you leave it in the "Reserve" position, and then you run out of gas, you push it to the gas station.



The tank only holds 1.8 gallons, so believe it or not, 1.2 is just about right for a refill right after switching to reserve.



Edit: I didn't realize lizrdbrth had already responded.
 

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Not a trick, but something I did for quick reference on the petcock. I painted the tip of the lever White. I put a Green dot of paint in the "on position", Yellow dot for "reserve", and Red dot for "off". Easy to see at a quick glance.



Now if your color blind ???
 

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6 o'clock position is on......9 o'clock is off and 1200 o'clock is reserve(this is in reference to an analog clock...some folks have never used or seen an analog clock...digital folks..eeekkkk!).
 

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The petcock on my 2009 has a small arrow on the edge facing out. It's small but is raised so if you get down close and look at it yours might have one too. Unless, as lizrdbrth mentioned, it could be a petcock from another model/year bike.



Byte
 

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Not to Highjack Boarder255's Original Question......But on the PetCock Subject: has there ever been a way to increase the size of the "reserve" tube? I wondered this as I installed my stock unit into a new Clarke Tank.

Bigger Tube=More Reserve??

Thanks.
 

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Not to Highjack Boarder255's Original Question......But on the PetCock Subject: has there ever been a way to increase the size of the "reserve" tube? I wondered this as I installed my stock unit into a new Clarke Tank.

Bigger Tube=More Reserve??

Thanks.
Simply slide a piece of tight-fitting fuel line on the reserve tube and clip it off the height you want. Might have to go to a hobby shop and use fuel line for a gasoline model to find a small enough diameter.
 

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How does a "bigger" tube (meaning taller?) = more reserve? If you make it taller, you will have more gas left in the tank that you can't access, which = less reserve. Make it taller than the Run position and you have switched the two functions, but will run out of accessible fuel much sooner.
 

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Nomenclature failure.



My petcock only has one tube. The tube creates the reserve. Hence, to me it seems it should be called the "reserve tube" since without it there'd have no reserve. When the petcock is in the "ON" position, it draws fuel through the tube. "RES" position has no tube--it draws directly off the bottom of the tank. Lengthen the tube, less "ON" and more "RES".
 
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