How to Fix a Leaking Motorcycle Petcock and Install a Fuel Filter

This is a demonstration of how I replaced an aftermarket fuel filter in a 1995 Kawasaki Vulcan VN800A. When doing this task I discovered the petcock was not closing completely, resulting in a constant slow internal leak of fuel to the carburetor. Fortunately the carb bowl float had not allowed fuel to leak past and contaminate oil or hydrolock the engine.
This repair shows how one can solve this problem without necessarily replacing all the seals or replacing the entire petcock.
The design features and vulnerabilities of motorcycle petcocks and fuel delivery are discussed.
This is an amateur demonstration, offered for free and in good faith but with no guarantees as to accuracy or safety. Before attempting repair of your bike, you need to decide whether you are willing to accept risk. Never rely on a single source for critical information. Any misadventure you encounter if you decide to accept the risks of DIY repair of your bike is your responsibility.
Music at the end is “River Meditation” by Audionautix,
licensed under a Creative Commons Attribution license (creativecommons.org/licenses/...)
Artist: audionautix.com/

[@billk5727]

Well done video and repair with explanations. Newer fuel blends are a bigger problem today than in times past. TakeCare, Bill

[@JahanZeb1976]

Wonderful work! Felt very good as am watching you after a long time.

[@angelaracino6236]

Great video my friend, always appreciate your thoroughness, you would make a great aircraft mechanic A/P. From your friends down in Fort Lauderdale USA

[@myrdryt]

@11:35 Something I learned recently. The direction of the fuel should go from Outside the filter to the Inside. Reason being so the filter can visually be inspected for a clog. And that is what the visual indicator is for, when available. Thanks for the descriptive video!

[@wyattoneable]

I had to replace the carburetor on my generator because of old, gummed up fuel. Nice work here. You always do a great job at explaining the process.

[@spelunkerd]

Thanks, Wyatt!

[@RuffianTux]

Excellent video. Brilliantly informative and superb quality.

[@spelunkerd]

Thanks, man!

[@thedon95376]

Great video and very thorough explanation appreciate it

[@KhalidMehmood-qh7no]

Very well explained. Thanks for your video.

[@DylanRabier]

Well explained sir. Thanks for sharing! 👍

[@jomanallen]

THANK YOU FOR THESE VIDEOS!

[@shawnmrfixitlee6478]

great share man , ENJOYED !

[@Jusdin057]

Great video mate.

[@giansgarbossa5403]

Kudos! Subscription definitely earned! With the rising cost of fuel and an itch for a project to keep me busy over the cold Canadian winter, I decided to purchase a motorcycle after an absence from riding for nearly 10 years. I found a 2003 VN800B that has been sitting in a shed, unused, for approximately 3 years. The bike runs( just barely) but for the price I got it for, could not pass it up. I am about to embark on a journey of complete rebuild/refresh. Came across your "Motorcycle Repair" video series when searching for how to rebuild the carburetor. I am by no means a mechanic (always used to get my bike serviced by professionals years ago) but fancy myself an above average tinkerer who generally gets good results given proper research and instruction. I watched all 13 of your motorcycle repair videos and found them to be informative, concise and, more importantly, a great visual tool which shows me procedure and explanation behind the cause of the fault. Shop manuals and written literature do not always show or explain teardown and reassembly procedures or why something went bad and what other systems might be involved. I believe that your videos are going to be an invaluable resource that I will be referring to over the next few months as I go through and renew all components and systems of my "new to me" toy! Well done Sir! Your new fan, Gian Sgarbossa

[@spelunkerd]

Kawasaki sell fairly inexpensive pdf copies of their dealer repair manual online at the Kawasaki website. It's not large but it is a helpful resource. Alternatively you can get copies off ebay and perhaps even free pdf copies from other sources. Good luck!

[@giansgarbossa5403]

@@spelunkerd Thank you for the tip! Will definitely check it out!

[@ozzstars_cars]

Years ago an old timer that owned a motorcycle service shop told me to just keep the manual petcock on always. I have done it for 25 years now and never had an issue. No leaks that way. 😁 Nice job with the vid Dave.

[@spelunkerd]

Ironically I don't know how long my automatic petcock was leaking, when mine failed I had no idea it wasn't doing its job. Manual petcocks make it easier to drain the carb bowl for winter storage, and they are a more reliable shutoff in the long term. On one of the forums a viewer actually installed a manual shutoff in line with his automatic petcock to get around the undetected leak issue. You make a good point, even with manual petcock left on you won't normally notice anything. Like seat belts or any other safety device, nothing happens unless something else goes wrong. Thanks for stopping by!

[@ezel4119]

Amazing video!

[@SVImpavidus]

Excellent Video. We used to ride bikes, Big ones across Europe and commute to work on them too. Thes knowledge sharing videos of yours are great value as the comments show. Ant & Cid (SV Impavidus)

[@spelunkerd]

Hey, thanks for stopping by! I watch your sailing videos all the time.

[@stuzman52]

Great work Dave in replacing the filter and fixing that leaking petcock! Have a great day!

[@MakeMajor]

thanks much! very good quality material

[@spelunkerd]

Glad you like it!

[@ethanmacheras5967]

Very helpful as my suzuki bandit might have this issues

[@joseloterry]

Very good video Amigo help me to understand the use of petcock

[@indiomechudo1]

thank you for the video

[@brentfranklin3557]

Nice thank y’all

[@MrJgem12345]

Where was this video 5 months ago when I googled everywhere and couldn’t find any info...

[@Blueknight-il9nc]

I think I have similar situation. The other day I noticed my 2003 Vulcan 800 gasoline was dripping out of one of the exhaust pipes. Seem to go away then it came back a day later. I’m wondering if my pet cock is failing and having fuel in the float bowl and mixing oil. I hope it’s not something major the bike seems to be running fine. But I am not gonna start it up until I fix the issue. Thank you for your videos helps a lot

[@dmaaljbore4605]

Thanks alot I wanna know how to change the gearbox because the 2d has crashed Kawasaki vulcan vn400

[@ray847]

I had the same problem on my 1996 vn800, I needed to replace the little o ring in the petcock and it stopped dripping,I did it yesterday. No dirt but the old one was just completely dried out. The garage I brought it to told me they done it already but they didn't.

[@ray847]

I have question about the petcock of which I replaced the little O-ring with success it seemed. I had to remove my gas tank again, because of oil seeping from behind my air filter housing. Now I notice when the petcock was in the "On " position there was no gas coming out of it when the tank was on the bike, but when I lifted the tank up (all hose disconnected) and moved it around a little it, with gas still in the tank it started dripping again, it stopped when holding it more to the just like when it is on the side stand, is this normal and it is just because vacuum is changing or should I replace more rubber rings and maybe the membrane?

[@cuff2860]

My Honda VTX has a persistent leak coming straight from the fuel petcock. Do you think it could be the o-ring? This will be my first big project that involves breaking the bike down so much so I'm apprehensive to say the least but you video has definitely cleared up some of the mystery. Thank you.

[@spelunkerd]

If fuel is leaking to the outside, you've definitely got a leak that could be traced back to a bad O ring or seal. You can buy seal kits for the original bike or replace the whole petcock for about the same price.

[@upraveen123]

Hi Spelunkerd...thank you for the clear explanation. Just want to confirm with you..Petcock ON= When riding and when parked (both short and long term), PRI=Only used When carburetor is cleaned and RES=When fuel low/used for the additional 20 Miles before running completely out of fuel.

[@spelunkerd]

Yes, exactly. Some people like to drain their carburetor bowl when they store the bike over the winter, since volatile components of the fuel will evaporate away and possibly leave a residue in the bottom of the bowl that can clog jets downstream in the spring when you start up. This bike has a threaded screw in the bottom of the bowl that makes draining the carburetor bowl easy. Leave any automatic petcock 'on' when you do that, and the only fuel that should drain will be in the bowl and the line leading from the petcock, less than 50 cc. if you get a bigger puddle of fuel under the bike after a few days you know the seal of the petcock is bad and needs to be cleaned or changed. So, it's a good test of whether your petcock is bad. Otherwise you might not ever know since the carb bowl needle valve should stop flow, too. In the spring, tighten that bowl drain screw, prime the line for a minute or so to clear the line of air and fill the line and bowl with fuel, then check for leaks and start the bike. Then remember to switch back from 'prime' to 'on'. Maybe I'm lazy but I gave up draining the bowl through the winter because it seemed like extra effort.

[@upraveen123]

@@spelunkerd thank you so much for your valuable advise. cant appreciate you enough. I will certainly try draining the carb as advised above before storing for winter..still trying to ride when I get a chance LOL. My love for DIY mechanics is dedicated to people like you on KZbin. Thank you once again

[@lonerider1976]

I have a 2nd hand Vulcan EN500 (1997) and needed the same explanation about the ON, PRI and RES. Thanks so much Mr. Spelunkerd for the explanation. Now I know to turn the petcock to ON when I park my bike short or long term.

[@zx8401ztv]

Ive never had a motorbike with a vaccume tap, but i guessed a spring and diaphagm of some sort could be the method :-). I must be a control freak as manual chokes and manual fuel taps i've always liked. It's what i got used to i suppose.

[@spelunkerd]

I know what you mean, it is a little disconcerting that one has no easy way to verify the automatic petcock has done its job. On the other hand, my biggest recurrent error over my lifetime has been the oversight. Many people forget or don't know why those should be off when not in use.

[@markwinchester3005]

Good advice: Turn valve OFF & let it run till it dies. No residual gas pooling in the float bowl. < Learned that the hard way. Decent petcocks are $20 off Amazon and can be replaced yearly..if need be, usually it lasts for years.

[@rhcp4life697]

I have a 72 Honda sl 125 that continues to slowly drip gas where the fuel line connects to the petcock, do you have any suggestions as to why? Nothing inside the petcock is cracked as far as I can tell, could it be the rubber o ring that holds the screen in place has hardened overtime and not properly sealing?

[@spelunkerd]

I wouldn't hesitate to replace the line, and clean the petcock while you are at it. I'd be on the look out for two problems, since a fixed line could silently drip internally through the carb. As shown, with the line removed there should be no dripping from an automatic petcock.

[@mydogdeli]

If there's no off position on automatic petcocks, did I understand you correctly that you don't need to run the bike dry before storing it for the winter? Very informative video. Thanks a lot for posting.

[@spelunkerd]

I run my carb dry, but it's not as easy as turning the petcock off, as you do with a manual petcock. The simple answer in the Vulcan is to turn the engine off and then drain the bowl by loosening the bowl drain screw. If you leave that screw open, you'll also be able to check to see if the petcock leaks. However if you do it that way, leave a tag on the tank to remind yourself that the bowl drain screw needs to be tightened up in the spring. Another option would be to simply pinch off the vacuum line on the petcock while the engine is running, then wait for it to die. I leave my tank full of fuel with a little fuel stabilizer added, to reduce the chance of rust forming inside the tank. I also pull out the battery to charge it in a warm garage intermittently through the winter.

[@mydogdeli]

@@spelunkerd great tips. Thank you.

[@EJ650RM]

Hi - at exactly 9:00 we sec the petcock and the nipple that comes from the bottom, does that have an O-Ring or is it just stuck in the bottom. I have a little drip and can pull it out.. not sure it I should just push it back in? Any ideas? Thanks,

[@spelunkerd]

The part in my left hand has a small black O-ring you can see, just above my left thumb at 9:00. That male part needs to seal properly or you'll have a leak. If the O ring is missing, cracked, or deformed you need to remove and replace it. My right index finger is touching the part where the tubing attaches, there is no O ring there or on any of the other hoses leading into the petcock.

[@need100k]

Very well done. I'm looking to buy a Kawasaki ZL1000 and the seller says it has a leaking petcock, so now I know what to do. I have a question though: Would there be any problem with replacing it with a manual petcock? I had that on my old Honda 450. I had a sticker on the tank that said, "turn the gas on, dummy" as a reminder to turn it on or off when needed. One complaint though: Wear gloves when handling gasoline please.

[@spelunkerd]

Sure, you could swap over to manual, but most would swap to an inexpensive automatic petcock. Ebay is full of them. Thanks for stopping by!

[@tsteel80]

I've got a 01 CB750 that has a bad leaking petcock. In the off its ok but when on it's a steady flow right onto the engine. What can I do?

[@spelunkerd]

If the petcock is automatic, with a vacuum line connected and no 'off' option, then the first thing I'd do is check the vacuum line for a small air leak, a tear in the tubing that might reduce the applied vacuum. Failing that, your option is to repair or replace it. Generic automatic petcocks are surprisingly cheap off of ebay or at your local shop. You could dismantle it to look for something trapped against the valve, like I did. In my case I had a tiny fragment of steel mesh, probably from the filter, trapped in the valve. When dismantling, be careful with gaskets which may be hard to source. Good luck!

[@glengerdes4158]

My vn 800 has a fuel screen built in to the fuel switch

[@firenzeracer1195]

Boa tarde meu amigo, sou do Brasil. A minha Vulcan Vn800 - 1996, está sem essa mangueira que aparece na foto. Poderia me informar onde conecto ela entre o filtro de ar e a moto ?

[@spelunkerd]

If you scroll the video to the exact part of the video showing the hose, then type the time stamp into your question, I'll be in a better position to understand what hose you're asking about. Type in the time stamps like this 3:23, the number shown at the lower left of your video screen, and youtube will automatically make a link that when clicked, scrolls the viewers player to the spot of the video showing the hose you are asking about. Sorry, I don't understand Portuguese, ha ha.

[@firenzeracer1195]

@@spelunkerd Thanks for returning my friend, I follow your videos here in Brazil, congratulations. In the videos the position is: 7:17 / 12:34. This hose that is connected, mine has no hose. Could you tell me where I connect this hose to the motor of the bike?

[@RfPrivateCollection]

@@firenzeracer1195 Salve mano também sou Brasileiro, passa seu whatsapp ai que eu posso ajudar com suas duvidas sobre a vulcan

[@Thumperwrestler]

what do you do if the filter in the gas tank on top of the petcock is torn?

[@spelunkerd]

Good question. Only two options, either replace it or remove it. The screen there is just a coarse screen, it isn't very good at filtering debris. In my case I put an inline fuel filter on, downstream of the petcock, so the only thing that screen is protecting is the petcock. If you can't easily find a replacement screen, I would leave it off. But be aware that the petcock with no inlet screen is more vulnerable to debris that could cause it to leak, and you may not know until your float needle also leaks and you get fuel overload and hydrolock. At the end of each season, I open the bowl drain on the carb, and I watch to be sure it doesn't continue dripping. If it does, the petcock is leaking.

[@myninja8136]

I recently got a vulcan 800 and it has a hose coming from the carburetor next to where the choke connects. It has a green band on it. The other end was hanging when i bought it and i cant find the connection can anyone tell me where it goes?

[@spelunkerd]

If you don't have a manual you could try the Kawasaki website, put in your model number and year, they offer free parts diagrams. There is a drain hose for the carb that drains oil from the air filter housing straight onto the pavement, kinda messy but meant to be there. At first I was puzzled by that hose but over time you'll see it does drain a little oil, which I think comes from blowby gasses fed from the crankcase. Any water vapor condensate also finds its way out of the air filter housing through that hose onto the road.

[@myninja8136]

@@spelunkerd ok thank you i will give the website a try. My bike actually has a little canister on the line from the air box to catch that oil.

[@elterrible3067]

My advice to any motorcycle owner or small engine for that matter: always add a fuel filter and never use gas with ethanol I don’t use it on my bike boat or any small engine such as generator, pressure washer etc.

[@user-rc4cb9ft9l]

What filter model did you install?

[@spelunkerd]

There is no OEM option so I went online and got a no-name generic option that I thought would be able to handle the heat so close to the cylinder heads. Because of that heat I excluded any with a plastic housing. My initial assumption was the line was typical 1/4", but I was wrong, that was too small. I don't remember for sure but I think it ended up being 5/16". That size is important because the tubing between petcock and carb is custom flared at the petcock end, so not easy to replace.

[@vinsonwalton28]

If you use premium fuel you will never have carb issues again. So what if premium fuel is 50 cents more a gallon. Its much better on small motor fuel systems

[@lotharr8414]

was bedeutet die Bezeichnung "PRI" am Benzinhahn ???

[@spelunkerd]

It means "Prime", which is used when you want fuel to flow even if there is no vacuum. Prime is useful when you replace the fuel tank and you want to purge an air pocket in the line. The bike will run fine when the petcock is in the prime position, but if you crash there is nothing to stop fuel flow so it could be more dangerous. Also, if for some reason the bowl needle leaks, a bike left in the prime position could allow gravity to flood the carb with fuel. That fuel could back up into the exhaust manifold in some bikes, flooding a cylinder that happens to have an open exhaust valve. If you crank the engine against a hydrolock, you could break a connecting rod and destroy the engine. Even if you don't damage the connecting rod, fuel making its way down the cylinder wall could contaminate the oil and cause cylinder scoring when the engine is later started.

[@ryandavis4689]

Mines leaking out the face plate where the knob is, there was a metal shim or gasket...i can't get itto stop so im searching KZbin for advice

[@spelunkerd]

There are both gaskets and O rings there. You can buy seal kits or ever replace the entire petcock. Many aftermarket petcocks are less expensive than trying to find seals for the OEM version.

[@thomaslockley945]

so if it leaks when u pull that vacumm line off ur peacock is bad

[@spelunkerd]

Yes, exactly. It won't necessarily cause any noticeable problem in the bike. If the needle valve inside the carb also goes bad, there would be nothing to prevent fuel from trickling through the intake manifold when bike is not running, into an open intake valve, possibly hydrolocking the engine. It is not a likely event but if it happens it could destroy the engine, because raw fuel won't compress like air does, so worth fixing. Also if the bike were involved in an accident it is a safeguard to prevent fuel from spilling around the scene.

[@thomaslockley945]

but the needle valve seat would not cause it to leak through the peacock ?

[@spelunkerd]

@@thomaslockley945 Yes you're right. If the petcock is working properly the position of the needle valve in the carb will have no effect, fuel can't move through a normal petcock without vacuum. So, it is a safeguard.

[@thomaslockley945]

ok thanks

[@chromevanadium5825]

I just replaced mine with Suzuki LT-80 vacuum petcock from ebay for just about 6 usd. No worth to repair. It fits on the tank exactly.

[@spelunkerd]

Excellent point, I'm sure this is the logic used at professional shops everywhere, where shop time also comes with a price tag. There is something upside down about our economy, when a seal kit costs more than a complete replacement, although quality and fit are issues, too. In the end I was able to get this going with no wait for a replacement. The whole time I was thinking exactly as you say.

[@chromevanadium5825]

@@spelunkerd I noticed that You still have an afterburner valve on Your bike ;) That's the hard to connect pipe behind the airfilter. Have You ever thought of getting rid of it as most of Vulcan ovners have done? Sounds funny, but the ecology thing also went wrong for this bike. By removing that whole stuff one can get a much better mileage. ( Search KZbin for EPA removal on VN800) Fuel economy is noticable. ( I have 4,9 liters/100 km. I live in Latvia) The engine runs cooler, no overheating pipes. I also replaced an intake airbox (under the fuel tank) with simple bent pipe to let the engine breath more properly. If you measure the intake hole on the box, You will find out that it is a little bit too small for intake in manifold (or even 36mm Keihin carburetor) So, the engine has air starving issues. Don't get me wrong! I'm not a fan of those modded bikes (I prefer OEM stuff) but this one is worth to think of. Good luck!

[@spelunkerd]

@@chromevanadium5825 Good point, I've never thought much about it. You've given me another topic to learn about, thanks for your input! Dave