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DRZ: Leaking Petcock

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Seems like after being warmed up and riden, my cycle, when shut off before putting it in the garage, will leak at the petcock (5-6 drops) which wick down the fuel line. I'd like to stick with the OEM vacuum petcock. Any suggestions to fix this?

 

Simple fix to tighten the bolts/screws on the back? Should I look for a petcock rebuild kit?

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Welcome to my nightmare. I decided to purchase the OEM petcock rather than take the chance of a rebuild kit failing. You can find a rebuild kit online that works very well. I'm sure someone on this forum can refer you to the brand name/company that sells them. I also replaced my needle valve assembly. The petcock leaked internally as well, then my needle valve started to leak and gas flowed into my motor. I check my oil level before each ride. I noticed it smelled like fuel and knew immediately I had the dreaded fuel leak problem. When I drained the oil I had 1/2 quart of fuel mixed in. I suggest checking your oil and replacing or repairing the petcock immediately. Mine leaked at the same rate as yours 5-6 drops.

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I just went through this whole thing last weekend. My 2003 DRZ400S was hydro-locked, so it took a while to figure out why, and how to fix. What causes the hydro-lock ? (gas fills the cylinder and engine won't turn over - at first appears to be a dead battery)

2 problems combined, one in the petcock, one in the carb. One can go bad before the other, but once you have both (and they are both very common) you get hydro-lock.

 

Basically, it comes down to 2 cheap o-rings that typically fail - one in the petcock, and the other in the carb needle valve assembly. This info below is for stock 400S carbs, NOT the E or FCR MX version.

 

The petcock fix - you drain gas, remove petcock, and take the back apart, carefully remove the guts. The back side of the large round metal diaphragm has a little o-ring on a center post. It goes bad, mine was completely crushed on one side. And then it leaks. The replacement is JIS size P4, or 3.8mm ID, 7.6mm OD, 1.9mm thick.

 

If you need it TODAY, you can likely get it at NAPA, my local store had a yellow box full of metric o-rings. It is also very close to, and can be subbed for metric size 007 (that is what they carried). Match the old one to the new one at the store.  

 

Some people also report using SAE size 3/16 ID, 5/16 OD, 1/16 section(thickness), but that converts to 3.9mm ID, 7.2mm OD, 1.5mm thick, and appears to be too small to me. 

For both units, make sure the o-rings are rated for gas. the best o-ring material to get, if ordering on line, is "viton" material. 

 

For the carb needle jet o-ring - that one is an oddball metric size. My old one measured about 7mm ID, 10mm OD, with a 1.5mm thickness. I used a common SAE 1/4 ID, 3/8 OD, 1/16 thick to replace it, and it worked OK. This size translates to 6.4mm ID, 9.5mm OD, 1.5mm thick. Some also report using the next size up, 5/16 ID (7.9mm) 7/16 OD (11mm) 1/16 thick, but this seemed to large for my bike, and fits loosely. I bought these SAE sizes in a pack of 16 assorted o-rings from Advance auto parts, for like $4. 

 

Of course you can also buy the OEM jet / needle / seat o-ring for $62., but this seemed like overkill to me, as the seat and needle (which is viton tipped) looked fine. And it is doomed to fail again. You really want Viton o-rings too if you can get them.  

 

After replacing both o-rings, the bike ran great. It was clear the carb jet o-ring had been leaking for a while, as it ran progressively worse for no apparent reason. It was running too rich, and had symptoms of the float being set wrong, even though it was dead on. 

 

Of course, after fixing and riding it, I found both o-ring sizes in viton material online, in the exact correct metric sizes. I ordered 2 dozen of each (the minimum), so have extra if anyone else needs them. 

Edited by BobNY
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I had the same problem with my Drz400S. I recently installed a Pingel Hi Flow petcock valve. $117 seems like a lot of money for a valve but %100 worth it IMO. One of the better mods on my dizzer. Here is the link bow if interested.

http://www.pingelonline.com/dirt-atv-fuel-valves/6191-ah61av-single-outlet-reserve-hex-valve-1-4-npt-6000-series-90-degree-5-16-hose-barb-with-adapter-aluminum.asp

ImageUploadedByThumper Talk1407177523.816872.jpg

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So an update all, fuel leaks only after I run my DRZ and then shut it off. It seems that fuel surges out of the fuel line above the clamp below the petcock. I may inspect my fuel line first and change the clamp prior to possibly rebuilding my petcock. Sound good?

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my petcock recently leak, which lead me to discover that my valve seat oring was bad. assuming you have stock CV carb, i read that the mikuni oring is a custom size.

 

I tried the standard at first, which i thought would be a closer fit to oem. size -011 which is 5/16ID 1/16CS. no matter how hard i tried to push it, it wouldn't fit. 

 

then i used a metric 8 x 1.5mm and it worked great.

 

i used viton because from my experience they are superior (except to silicone (orange) for high heat applications), but im guessing buna should be fine as well. 

Edited by accuracy

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I just went through this whole thing last weekend. My 2003 DRZ400S was hydro-locked, so it took a while to figure out why, and how to fix. What causes the hydro-lock ? (gas fills the cylinder and engine won't turn over - at first appears to be a dead battery)

2 problems combined, one in the petcock, one in the carb. One can go bad before the other, but once you have both (and they are both very common) you get hydro-lock.

 

 

I had the impression that if you experience hydrolock your rod would bend, or something else in your motor gives.

I think you are describing a flooded engine

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I had the impression that if you experience hydrolock your rod would bend, or something else in your motor gives.

I think you are describing a flooded engine

 

Nope, hydrolock is when your cylinder fills up with a liquid, which is a non compressible fluid. If that happens when the motor is running under load, you will likely do major damage. Usually this can happen that way if you screw up and drive your bike into a river that's deeper than you thought - the water is higher than the air cleaner inlet height. 

 

In most cases with the DRZ400 (that have 2 worn out o-rings as I detailed above), hydrolock happens when the bike is sitting, and has not been started for a while.  

The gas slowly seeps down through the petcock, then through the carb, through the intake manifold and valves, completely filling the cylinder. It also weeps past the rings into the oil crankcase. 

If you try to start it like this, it won't. It simply will not turn over. You get a click from the starter that sounds like the battery is dead. The cure is to remove the spark plug, and then run the starter, emptying (more like spraying) all the gas out the spark plug hole. Then it will turn over and run again. But you should always change the oil first before running if that happens to you.

 

Check this out for more experiences with this   http://tinyurl.com/lj4z9md

 

Flooding is what rookies do when trying to start an engine with the choke on full, and usually too much throttle, for too long. The motor will turn over fine, but not start. If you pull the spark plug, it will be soaking wet with gas. Most modern bikes should be started with your hand off the throttle, or maybe opened a slight bit, then shut quickly 

Edited by BobNY
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So an update all, fuel leaks only after I run my DRZ and then shut it off. It seems that fuel surges out of the fuel line above the clamp below the petcock. I may inspect my fuel line first and change the clamp prior to possibly rebuilding my petcock. Sound good?

 

Yes, did not realize your drips were external to the fuel line.

 

Try rotating the fuel line at the petcock to see if it turns easily. If so, it is likely leaking due to a loose clamp or worn out line.

 

If tight, I would also first check all the petcock screws for tightness before going to the next step. If you do open it up, put in a new o-ring, as they all go eventually. Not sure they really require a full rebuild kit - mine's a 2003 and everything looked good except the o-ring. I guess it also depends on your local fuel, and what additives you do, or do not use, though. 

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Yes, did not realize your drips were external to the fuel line.

 

Try rotating the fuel line at the petcock to see if it turns easily. If so, it is likely leaking due to a loose clamp or worn out line.

 

If tight, I would also first check all the petcock screws for tightness before going to the next step. If you do open it up, put in a new o-ring, as they all go eventually. Not sure they really require a full rebuild kit - mine's a 2003 and everything looked good except the o-ring. I guess it also depends on your local fuel, and what additives you do, or do not use, though. 

 

BobNY, I will check it out today and let you know. If I must open my petcock, are there multiple o-rings or a main one which may be the issue/need to be replaced?

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my petcock recently leak, which lead me to discover that my valve seat oring was bad. assuming you have stock CV carb, i read that the mikuni oring is a custom size.

I tried the standard at first, which i thought would be a closer fit to oem. size -011 which is 5/16ID 1/16CS. no matter how hard i tried to push it, it wouldn't fit.

then i used a metric 8 x 1.5mm and it worked great.

i used viton because from my experience they are superior (except to silicone (orange) for high heat applications), but im guessing buna should be fine as well.

I had the same problem. My valve seat O ring was bad with my stock CV carb, and apparently they go bad very often. One of the first mods is to replace the stock Petcock valve. Why would they make a carb that has no OFF switch. I can't tell you what a difference the pingel valve made. At first I replaced my stock valve with a fleabay valve that was around $15 with a on off res but that one was a joke and leaked while in the off position. I wouldn't be able to go on the free way as not enough gas was flowing. Would bog out and die while

I was riding in 5th at around 80mph on freeway. Now I can cruise at 80 and still have a handful off throttle left. I can feel the gas flowing unlike ever before. Feels and rides like a new bike now. Can't say enough good things about the P valve. Ever since I upgraded the valve I haven't had one issue with the bike. Goodluck with your dizzer

ImageUploadedByThumper Talk1407259983.366855.jpg

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Yes, that is the o-ring that goes bad. I would get just the o-ring, it's usually available at a NAPA autoparts store as above (metric size 007 is how it was marked). If apart, you can get it today and be riding later. 

 

For the front petcock gaskets (accessed by 2 screws), I turned over the smiley face gasket and big O-ring and re-used them. 

 

When the stock petcock is working OK, it turns the gas off fine when the engine is stopped.

 

You can get a new petcock if it makes you feel better, but of course then you need to remember to turn it off. And replacement units all have a smaller reserve than the stock petcock (the long vertical gas pickup tube is shorter than stock).  

 

The Yamaha raptor petcock is a popular replacement, but has a horizontal hose outlet barb. Sold here - 

https://www.thumpertalk.com/shop/Yamaha-FUEL-COCK-ASSY-1-5LP-24500-01-00-p1000322768.html

 

If you go Pingle, make sure you know which way the fuel outlet is going before making your buy - they sell it both to the side, and going down. Which one you want depends on the tank you are using - with an oversize Clarke tank, I'd get the side exit. With a stock tank, bottom exit.

There is also a guy on EBay selling side and bottom exit valves -

http://www.ebay.com/itm/DRZ400-DRZ-400-KLX400-KLX-PETCOCK-FUEL-VALVE-GAS-HOSE-BARB-FACING-DOWN-/250958030900?pt=Motorcycles_Parts_Accessories&hash=item3a6e43a834

 

good luck

Bob 

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Yes, that is the o-ring that goes bad. I would get just the o-ring, it's usually available at a NAPA autoparts store as above (metric size 007 is how it was marked). If apart, you can get it today and be riding later. 

 

For the front petcock gaskets (accessed by 2 screws), I turned over the smiley face gasket and big O-ring and re-used them. 

 

When the stock petcock is working OK, it turns the gas off fine when the engine is stopped.

 

You can get a new petcock if it makes you feel better, but of course then you need to remember to turn it off. And replacement units all have a smaller reserve than the stock petcock (the long vertical gas pickup tube is shorter than stock).  

 

The Yamaha raptor petcock is a popular replacement, but has a horizontal hose outlet barb. Sold here - 

https://www.thumpertalk.com/shop/Yamaha-FUEL-COCK-ASSY-1-5LP-24500-01-00-p1000322768.html

 

If you go Pingle, make sure you know which way the fuel outlet is going before making your buy - they sell it both to the side, and going down. Which one you want depends on the tank you are using - with an oversize Clarke tank, I'd get the side exit. With a stock tank, bottom exit.

There is also a guy on EBay selling side and bottom exit valves -

http://www.ebay.com/itm/DRZ400-DRZ-400-KLX400-KLX-PETCOCK-FUEL-VALVE-GAS-HOSE-BARB-FACING-DOWN-/250958030900?pt=Motorcycles_Parts_Accessories&hash=item3a6e43a834

 

good luck

Bob 

 

Bob, I may order a rebuild kit for my OEM petcock, but also order this: http://www.pingelonline.com/dirt-atv-fuel-valves/6190-ah61av-single-outlet-on-off-hex-finned-valve-1-4-npt-6000-series-90-degree-5-16-hose-barb-with-adapter-aluminum.asp

 

With the Pingel valve (outlet down), I'd just have to get shorter bolts to mount it to the tank?

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Just make sure the stuff about high flow rate petcocks does not go to your brains. Here's the numbers -

 

At 80 mph, if the DRZ400 gets 40 mpg (it gets much better, probably 60-70 MPG) you would use 2 gallons per hour. Two gallons = 256 ounces. You flow rate needed to keep up, in ounces per minute is 256 ounces / 60 minutes per hour = 4.2 ounces per minute.

 

On the Pringle webdite they say OEM petcocks "only" deliver 30 ounces per minute, ?!, but their high flow rate versions deliver 90 and 210 ounces per minute!

Do you see why this is of no importance at all, when worst case you need 4.2 ounces per minute or less?

 

Even if you were at the "OEM" rate of 30 ounces per minute, you would be burning 14 gallons per hour. To exceed this flow rate, your vehicle would be getting worse than 5 MPG at 70 MPH. This is perhaps the burn rate dual engine 454 cu in racing boats, not DRZ400's!

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Just make sure the stuff about high flow rate petcocks does not go to your brains. Here's the numbers -

 

At 80 mph, if the DRZ400 gets 40 mpg (it gets much better, probably 60-70 MPG) you would use 2 gallons per hour. Two gallons = 256 ounces. You flow rate needed to keep up, in ounces per minute is 256 ounces / 60 minutes per hour = 4.2 ounces per minute.

 

On the Pringle webdite they say OEM petcocks "only" deliver 30 ounces per minute, ?!, but their high flow rate versions deliver 90 and 210 ounces per minute!

Do you see why this is of no importance at all, when worst case you need 4.2 ounces per minute or less?

 

Even if you were at the "OEM" rate of 30 ounces per minute, you would be burning 14 gallons per hour. To exceed this flow rate, your vehicle would be getting worse than 5 MPG at 70 MPH. This is perhaps the burn rate dual engine 454 cu in racing boats, not DRZ400's!

 

Thanks Bob, that's some good info. I just figured I'd try the Pringel. I was really just fearful of having a leak and potential hydrolock over the winter. Others seem to have success with Pringel so I went with them. Always good to know that I could fall back on the Raptor petcock too.

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I had the same problem with my Drz400S. I recently installed a Pingel Hi Flow petcock valve. $117 seems like a lot of money for a valve but %100 worth it IMO. One of the better mods on my dizzer. Here is the link bow if interested.

http://www.pingelonline.com/dirt-atv-fuel-valves/6191-ah61av-single-outlet-reserve-hex-valve-1-4-npt-6000-series-90-degree-5-16-hose-barb-with-adapter-aluminum.asp

attachicon.gifImageUploadedByThumper Talk1407177523.816872.jpg

Not to be too picky but what could this petcock do for me that my $24 Yamaha petcock doesn't?

....just saying.....

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Route the fuel line better

 

Only for the stock tank. For the big Clarke tank the petcock location is about 2-3 inches lower, and the bottom exit petcock makes the line have a U shape, not optimal, subject to pinching it shut. The see through plastic hoses will likely kink / restrict fuel - been there. The pre-molded stock hose with a molded in 90 bend works for me in that case (I have a Clarke tank).

 

If you NEED a bottom exit, the Brown Family Racing petcock, which has supporters here, sells for 40. shipped, about 1/3 the price of the Pringle.

It also allows swapping the stock reserve tube, if having a stock reserve capacity is important to you.

Link above, or here again

http://www.ebay.com/itm/DRZ400-DRZ-400-KLX400-KLX-PETCOCK-FUEL-VALVE-GAS-HOSE-BARB-FACING-DOWN-/250958030900?pt=Motorcycles_Parts_Accessories&hash=item3a6e43a834

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