Question about 2007 AJP PR4 200 Supermotard

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Petcock What's the petcock for? How do I use it?

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It’s a Main/Reserve fuel valve. Its purpose is to select which of two tubes the fuel pump uses to get fuel from the fuel tank. One of the tubes is at the bottom of the tank; the other is about an inch higher. The normal “On” position gets fuel from the tube with the higher opening. When it runs dry you switch to “Reserve” which gets that last gallon or so from the bottom of the tank. That gives you enough range to make it to the next gas station for a fill-up. ,

Posted on Nov 10, 2008


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Posted on Jan 02, 2017

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SOURCE: fuel petcock

The petcock is what the fuel flows through when it comes out of the gas tank. It probably includes: * A switch with positions for On, Off and Reserve. * A fuel line going to the carburetors. * A vacuum hose attachment which attaches to a carburetor which tugs on a rubber diaphram to let gas flow through. * An overflow/drip valve from the vacuum area. It's located right under the tank on the rear/left side.

Posted on Nov 10, 2008

  • 17 Answers

SOURCE: i have two loose hoses coming off my petcock? where do they go

On your silverwing you have a "vacuum operated petcock" which means that the carbs draw a vacuum and allow the fuel to flow from the petcock. The front hose is the vacuum hose that should run to the center of the carbs. The second is a drain hose - it's advised that you do have a small hose connect here, so that dirt does not find its way into the petcock. This hose will simply run down past the swing arm to the ground. This would prevent any gas from dumping itself onto the engine if your petcock fails. If your bike runs without the vacuum hose attached, your petcock has failed and will need to be rebuilt.

Posted on Jun 15, 2009

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SOURCE: 1985 Yamaha xj700 Maxim- Carb. fuel lines

yes, the breather line hooks to the petcock on the line facing the back, the fuel line hooks to the larger one. the line from the breather is actually a vacume line that turns on the fuel, without it you will not get fuel out of the petcock unless it is in the prime position.

Posted on Jul 04, 2009

  • 379 Answers

SOURCE: HD 1979 fatboy fuel petcock valve leaking

Replace the petcock. The rubber diaphragm is ruptured. I'd also bet your fuel mileage dropped cause the ruptured diaphragm is allowing raw fuel to be sucked into the intake manifold.

Posted on Jul 23, 2009

  • 188 Answers

SOURCE: My Honda Shadow Aero 750 has fuel coming out of

Replace petcock assembly and any gasket to tank. Not an item you want to play around with too much because of risk of fire.

Posted on Jul 26, 2009

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Where is petcock located

Hi, J left side towards the rear of the gas tank on the bottom for more information about your question and valuable "FREE" downloads that you will need please click on the websites below. Good luck and have a nice day.
Where is petcock located on motorcycle Google Search
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Apr 17, 2016 | Motorcycles

1 Answer

Fuel tank petcock vacuum operated

What exactly is the problem with the petcock? If it is a vacuum operated petcock and it is no longer allowing fuel to the engine check the following:

First, did you work on the bike prior to the problem occuring, and was the bike running properly before this? On bikes I've owned with vacuum petcocks, the petcock has two rubber hoses attached to it. One is the vacuum line the other is the fuel line. On one of my bikes these hoses were nearly identical in size and I managed to swap them a couple times after having the tank off the bike. Simply double check that the hoses are connected properly. If they are not, the bike will run until the fuel is run out of the float bowls then die.

Second, do you have an inline fuel filter on the fuel line between the petcock and carb? If so check it to make sure it is not clogged.

Third, remove the tank and check the entire length of the vacuum line for the petcock. Is it kinked, pinched, cracked, cut, detached, etc.? Look for anything which would prevent the line from providing vacuum to the petcock.

Fouth, test the petcock to see if it is working properly. To do this you will need a handheld vacuum pump, such as a Mityvac (you may be able to get a free loaner from some autoparts stores). remove the vacuum line from your petcock and attach the vacuum pump to it. It should only take one or two pumps to create enough vacuum to open the petcock valve. If fuel begins to flow the petcock is good, if it doesn't you could have a clogged filter screen in the tank, but most likely the petcock's vacuum diaphram is damaged. The Baha is a Chinese made bike and it's possible the rubber parts in the fuel system are not compatible with the ethenal fuel blends here in the U.S. The dealers who sell these bikes are really hit and miss when it comes to being able to provide replacement parts. Even with the internet, it may take some work to locate a correct replacement petcock for the bike. On the bright side, if you are able to get a new petcock, they are very easy to replace.

Good luck!

Nov 29, 2013 | 2011 Bajaj Pulsar 150

1 Answer

Seems to be a fuel problem, fuel not getting thru to cylinders but runs on easy-start (did this to eliminate poss. electrics problem) fuel tank full and switched on !!!

Don't use too much of the starter fluid. This stuff is bad on an engine as it can crack cylinder heads and pistons. Check the fuel petcock on your fuel tank. In 1996, Harley went to a vacuum controlled fuel petcock and they do give troubles. To check it, pul the fuel line off at either the petcock or the carburetor fuel inlet. Turn the switch on and spin the engine. You should see a good stream of fuel come out of the hose or the petcock. If not, check to make sure the vacuum line is hooked up to the backside of the petcock. If it is, you may have a hole in the diaphragm in the petcock. You must loosen the petcock and allow the fuel to drain out of the tank. Catch it with a large funnel and an empty fuel can. Take the petcock out of the tank and take the plate off the backside of the petcock. There's a needle and diaphragm under the plate. Notice how it comes out so you can put it all back together. Hold the diaphragm up to the light and gently stretch it while looking for a hole. You can get a replacement diahpragm from your local dealer. I'd much prefer to simply replace the petcock with a high quality manually operated petcock and plug the vacuum line. Of course, then you'll have to turn your gas on and off manually, old school style.

Good Luck

Jul 30, 2011 | 2000 Harley Davidson XL 1200 C Sportster...

1 Answer

Sportster 883 /2001 start ok running for a few minute and then shut down alredy change spark plug and coil .brought second hand ignition module but still doing the same

Check the fuel flow through your petcock. In 1996, Harley went to a vacuum operated fuel petcock. Vacuum from the engine opens the petcock, when the engine is not running and no vacuum, the petcock closes. These things give a lot of trouble. If there is a hole in the diaphragm or a cracked or loose vacuum hose, no fuel flow or insufficient fuel flow. If you have a hand operated vacuum pump, connect it to the backside of the petcock, Apply a little vacuum and see if it "holds" or if it leaks down. Disconnect the fuel line and see if the fuel flow looks sufficient. If not in either case, you'll have to take the petcock out and take the rear plate off. Take note of how the parts come out. Hold the diaphragm up to the light and gently stretch it looking for holes. If you find a hole, replace the diaphragm. Check the petcock to make sure no passageways are blocked. Personally, I suggest changing the petcock to a high quality replacement manually operated petcock. Problem solved permanently.

Good Luck

Jun 01, 2011 | 2001 Harley Davidson XL Sportster 883...

1 Answer

Harley turns over but does not fire i checked fuses they are good i drained the fuel tank to make sure there was not any thing in the filter but i dont know if it is getting gas gas does not come out of...

You didn't say what year or model your bike was so I'll just take a guess here. In 1996 and later, Harley started putting vacuum operated petcocks on their bikes that are equipped with a carburetor. It should have a small vacuum line running to the backside of it unless someone has changed the petcock to a manual operated one. The vacuum line comes off the backside of the carburetor and supplies vacuum to the VOES switch and the petcock.

If it is a vacuum operated petcock, it will have a square plate on the backside with four small screws holding it on. Take the screws out and carefully remove the plate. Notice how the stuff in there comes out. There is a spring, a needle, and a diaphragm in the petcock. Hold the diaphragm up to the light and gently stretch it while looking for a hole. If you find one, put a new diaphragm in the petcock. Upon reassembly, connect the vacuum hose and turn the petcock to the normal run position. Leave the fuel hose off and spin the engine. Fuel should flow from the petcock. If you have a hand operated vacuum pump, you can connect it to the petcock and apply vacuum to get the fuel to flow.

Personally, I suggest changing the petcock to a high quality manually operated petcock and turn your fuel on and off manually. Old School style. Pingel makes a very high quality petcock. They aren't cheap but you'll never have another petcock problem.

Good Luck

May 16, 2011 | Harley Davidson FLSTF Fat boy Motorcycles

1 Answer

Bike runs for a mile then stops

You didn't tell me what year Sportster we're dealing with. So, I'll cover a few general things to check.

If your bike is running for about a mile and then stopping and it does this repeatedly, It sounds like a fuel problem. Most likely it's either the petcock or the fuel tank vent system.

First, If your bike is made after 1996, it probably has the OEM vacuum operated petcock. These petcocks are designed to open when the engine is running and close when it stops. There is a small vacuum line that plugs into the backside of the petcock. When the engine is running, this line supplies the vacuum. Check the line and make sure that it hasn't come loose or cracked. It originates behind the carb and goes upwards underneath the tank to the VOES switch and it has a "Y" in the line that reduces the size and then runs to the backside of your petcock.

If it is intact, you'll need a hand vacuum pump to test the petcock for proper operation. Connect the vacuum pump to the rear of the petcock. Remove the fuel line from the petcock. Now, apply vacuum to the petcock with the pump. Fuel should flow from the petcock. If not, the petcock is either bad or the strainer in the tank is stopped up.

Remove the petcock from the tank. Place a large funnel under the petcock and direct the funnel into an empty gasoline can large enough to hold all the fuel in the tank. Loosen the petcock enough so that the fuel runs out at a rate that you can control. When empty, finish removing the petcock from the tank. Inspect and clean the screen. Now, on the back side of the petcock is a square plate held on by four screws. Remove the screws and remove the plate. Underneath the plate you'll find a diaphragm. Hold the diaphragm up to the a light and gently stretch it and look for holes. If you find a hole, you'll have to replace the diaphragm.

Look inside the petcock where the needle is for trash. At this point you should be able to blow back up through the petcock to check for obstructions. Reassemble petcock and reinstall in the tank.

I've seen these petcocks give a lot of trouble exactly like you're experiencing. I recommend that you replace the petcock with a manually operated petcock. The Pingle petcocks are very high quality units but a bit pricey. If you'd rather stick to an OEM type unit, purchase a petcock from the Harley shop for a 1995 or earlier model. This will be a manually operated petcock. Plug the vacuum hose that you'll no longer need. You'll have to get into the habit of turning the gas on and off whenever you get on or off the bike like the old timers did. But, they'll never let you down.

Now, remove the fuel cap. Wipe it down real well with a clean cloth. Now, make sure your friends are NOT around for this test or you'll never hear the end of it. Put the threaded end of the fuel cap up to your lips and try to **** and blow through the vent. If you cannot, the vent is bad and you're not getting gasoline to your carb due to a buildup of vacuum in the tank.

Good Luck

Jul 15, 2010 | 2000 Harley Davidson XL 1200 C Sportster...

1 Answer

Wont stay running,like its out of gas. but its not

It may indeed be out of gas. You can have a full tank of fuel and be "out of gas" in the carb. The culprit could be the vacuum operated petcock. The petcock has a diaphragm in it that is opened by engine vacuum. If that diaphragm is not functioning as it should, no gasoline gets to the carb.

To test the petcock, reach around behind it and feel for a small vacuum hose. Unplug this hose and replace it with a hose you can **** on. Using your mouth, **** on the hose with the fuel line disconnected. You should see fuel flow out of the petcock. If not, you must drain the tank by loosening the petcock and allowing the fuel to run out of the loose petcock. Use a large funnel and an empty fuel container to catch the fuel. Once the fuel tank is empty, remove the petcock. Take the plate on the back of the petcock off by removing the four small screws. You'll find a diaphragm, a small spring, and a needle. Hold the diaphragm up to the light and stretch it gently. If you find a hole in the diaphragm, replace it. Check the petcock for obstructions by blowing through it. Reassemble the petcock and test it again.

Check the hose that supplies the vacuum to the petcock. It comes from the backside of the carb and runs upwards to the VOES switch and then reduces in size and goes to the petcock. Make sure it's connected and has no holes or cracks in it.

If everything looks alright, replace the petcock, connect the hose and try to start your bike again.

These petcocks are notorious for giving problems. I always recommend that the vacuum operated petcock be replaced with a high quality manually operated petcock such as a Pingle. They're expensive and require you to manually turn the gas off like the "old school bikers" do but they won't leave you stranded out of gas with a full tank of fuel.

Good Luck

Jun 17, 2010 | 2003 Harley Davidson XLH Sportster 883...

2 Answers

What is the open position for the fuel petcock...parallell to the ground? Or is is it perpendicular...basically which way is ON, OFF, RESERVE?

The petcock on your bike is supposed to be one of the vacuum operated type petcocks. When the engine is started, the vacuum from the engine is supplied to a diaphragm on the backside of the petcock open the fuel valve. It may have been changed since these valves were notorious for problems.

Your petcock should be labeled "ON", "OFF", and "RES" if it's a manual petcock. There should be and arrow on the lever on the petcock as well. This is the best advice I can give without being able to look at the petcock. I hope it helps. GOOD LUCK and ride safe.

Apr 01, 2010 | 2001 Harley Davidson FLSTF - FLSTFI Fat...

1 Answer

My 1998 Dyna has a small leak or drip coming from petcock

Sounds like you have a hole in the vacuum diaphragm that opens and closes the petcock. This is one of the problems with the vacuum operated device. The other problem is that sometimes they don't open and you're left stranded with a full tank of gas and not a drop in the carburetor. I changed to a manual operated petcock. Personally, I'd rather have a Pingle petcock than another vacuum operated Harley petcock. If you do change to a manual operated petcock, don't forget to plug the small vacuum hose.

If you want to keep your vacuum operated device, I think you can buy a replacement diaphragm. You will have to drain the tank and remove the petcock. There are four small screws on the backside. Remove the screws and the backplate will come off. The diaphragm and a sping is all that is in that section of the petcock.

Mar 31, 2010 | 2000 Harley Davidson FXDWG Dyna Wide Glide

1 Answer

The fuel wont go through the lines to get it started

You're bike may be equipped with a vacuum operated petcock. See if the fuel valve has a "prime" position on it. If so, put it in this position. If you still don't get any fuel to the carb, you'll have to remove the petcock from the tank and clean the screen or unstop the petcock. I'd put a manual petcock in and block the vacuum line.

If you already have a manual petcock and you're not getting fuel, remove the petcock, clean the screen, and blow air through the petcock in both the "On" postition and the "Res" position.

Nov 17, 2009 | 1981 Yamaha XJ 650

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