Petcock on Motorcycle: How To Fix a Leak in Simple Steps

Petcock on motorcycle that’s leaky can cause many engine problems, so it’s essential to fix the issue as soon as it’s noticed. To do that, drain the oil in the gas tank, remove the petcock, and try to repair it or install a new one.

Petcock on Motorcycle

Continue reading, and let’s discuss that in length below, including tips to keep the petcock pristine. We will also mention notorious symptoms of a malfunctioning fuel valve petcock so you can fix it on time and prevent expensive repairs.

How To Repair a Leaky Petcock on a Motorcycle?

To repair a leaky petcock on a motorcycle, drain the fuel and remove the petcock for a closer inspection. If it can be cleaned and repaired, do it or install a new petcock. After that, replace any worn-out related components, add fuel, and see if the leaks are fixed.

Petcocks, sometimes called fuel taps, faucets, or cock valves, are two or three-way fuel shut-off valves on the fuel tanks in motorcycles with carburetors. A carburetor requires a petcock to control fuel flow to the engine. Without a petcock, the carburetor would push all the fuel into the engine at once. That would lead to the engine running too rich and flooding.

The petcock enables the carburetor to adjust the fuel flow based on the amount of power the engine needs. How does a petcock work? Well, there are two types of petcocks: gravity-fed and vacuum-operated petcocks.

Most petcocks have three positions, namely the reserve position, which accesses the bottom part of the tank, the ON position, and the closed position (OFF), used to block the fuel from flowing out of the tank.

On the other hand, vacuum-operated systems may have a prime position (motorcycle petcock prime) that bypasses vacuum operation, allowing fuel flow into the carburetor without your engine turning over. When there’s no vacuum, a spring holds a small gasket in place, stopping the fuel flow. But when the vacuum is applied, the valve diaphragm is pulled in, allowing the fuel to flow again.

A petcock is a critical part of the bike. It allows you, the rider, to control the fuel flow to the engine. Thus, it’s essential to ensure that the petcock works appropriately to get the most out of the motorcycle. Here’s our detailed guide to deal with the “motorcycle petcock leaking” problem, but first, you’ll need the following tools for this DIY task:

  • A 10mm wrench
  • Screwdriver
  • Fuel container
  • Needle-nose pliers
  • Stiff clean brush (a toothbrush is sufficient)
  • Coffee filter
  • A funnel
  • A carburetor cleaner (which can be purchased at a local auto parts store or online)

1. Find a Good Working Place

Find a good, well-ventilated place to work comfortably. It could be outside or in a ventilated garage. This task will require disassembling motorcycle components. Ensure the place is clean and well-lit so you won’t displace things like nuts and screws.

Good Working Place

2. Drain the Fuel

Ensure the motorcycle gas tank petcock is closed, then pull out the fuel lines connected to it. Set up the coffee filter in the funnel, then open the fuel petcock valve to drain the tank into the fuel container. Ensure both fuel lines flow evenly. You can make things easier by removing the tank and placing it somewhere.

3. Remove the Petcock

Once you drain the fuel, grab your 10mm wrench and remove the gunk collector at the bottom of the petcock. Next, extract the inner screen and gasket using a pair of needle-nose pliers. At this point, you should see the screw holding the petcock onto the tank. Use the screwdriver to remove the screw.

Removing Motorcycle Petcock

The petcock may be threaded into place at the bottom of the tank. In that case, you’ll still use your wrench. You may need to cover the painted surface with masking tape to prevent accidental scratches by the wrench. Disconnect the fuel line, then turn the petcock anticlockwise until it comes out.

4. Repair or Install New Petcock

Thoroughly clean the tank opening with the brush first. After that, clean the petcock and examine it for any signs of damage. You only need to clean and reinstall it if it’s not broken.

Clean the petcock fuel valve with a carburetor cleaner to remove grease and dirt buildup that could be causing the leak. It would also help to apply some lubricant to the petcock body and lever.

If the petcock is damaged, buy a new replacement part. Some petcocks are made to be used once and then thrown away when they go bad, particularly the rivet-style petcocks. Luckily, petcocks are inexpensive. You can buy one at most auto parts stores for as low as $15, although the cost can increase if you also need to replace the gasket or spring.

Ensure the threads on the tank aren’t damaged, then put the cleaned or new petcock straight in place and secure the screw. Next, replace the screen and gasket. Screw on the bottom piece and tighten its nut with a wrench.

5. Replace Related Components and Test for Leaks

Once you’ve reinstalled the motorcycle fuel petcock, it’s essential to check the condition of the fuel lines and hose clamps and replace them if necessary. Old fuel lines or weak hose clamps are prone to leaks, and replacements are inexpensive.

After that, add gas to the tank, then check and address any leaks. When you’re sure there are no leaks or clogs, replace the tank (if you had removed it) and then reconnect the fuel lines to the new or repaired petcock. You can now fire up the engine.

How To Know If You Need a Petcock Replacement?

To know if you need a petcock replacement, watch out for the common symptoms of a failing petcock. One of them is a leak, which could result from worn-out gaskets or diaphragm seals. A failing petcock can also affect your bike’s overall performance and trigger a flooded engine.

Taking action as soon as you notice one of the above symptoms can prevent further engine damage. Please do not ignore any sign of petcock issues, or else you’ll be faced with expensive repairs.

  • Leaking Petcock

The most typical symptom to watch out for is a gas leak. A leaking petcock can waste a lot of fuel if you take time before taking action. The leak could result from many things, including worn-out gaskets or o-rings inside the petcock assembly.

One of the common vacuum operated petcock problems is worn-out diaphragm seals, equivalent to gaskets in gravity-fed systems. When the diaphragm materials get tone, they lose their ability to hold a vacuum. That causes fuel to leak via the petcock even when on the off position. If your petcock leaks, then know that the gaskets/diaphragm seals or the petcock itself probably need a replacement.

  • Reduced Overall Performance

Many things could cause the performance of your Honda motorcycle to reduce. A problematic petcock is one of them. As mentioned, some petcocks have a fuel screen (filter) on the tank side, which helps to block dirt and debris from entering the tank and causing engine issues down the road.

The filter is a maintenance item, and if neglected, it may restrict the fuel supply or fail, allowing debris to pass through. If you notice a gradual reduction in performance, your petcock may be at fault.

  • Flooded Engine

Another symptom that you probably need to replace the petcock is a flooded engine. A flooded engine means too much fuel flows in, perhaps due to a leaking petcock. The problem can also occur when the seals in the petcock fail, causing the fuel to flow into the carburetor and eventually drain into the cylinder. Worst-case scenario, this can cause the engine to hydro lock, requiring costly repairs.

Flooded Engine of Motorcycle

However, some components may function and make you think it’s the petcock at fault. For instance, a failed kinked fuel line may be due to improper installations that can trigger engine flooding. 

Thus, contacting a professional for an accurate diagnosis is essential before hurriedly replacing the petcock. If you need contacts for an expert, search “repair motorcycle petcock near me” on the web and see if you find a number to call.

How To Keep Your Motorcycle Petcock Pristine?

To keep your motorcycle petcock pristine, regularly clean it and the fuel tank to avoid grime buildup, breakage, and leaks. Also, check for leaks and fix them as soon as possible. Consider upgrading or replacing the part with a more superior one.

  • Clean the Petcock Regularly

How often you should clean your petcock depends on how frequently you ride and how dirty the bike gets. Please clean the petcock routinely if you ride the bike daily. A motorcycle constantly running on dusty roads will also require more frequent cleaning. For example, you could do it once every three months.

Cleaning Motorcycle Petcock Regularly

However, if you ride only a few times a month and the bike runs on paved roads, you could schedule a cleaning every once a year. On average, you should clean the petcock at least once every six months.

  • Keep Tank Clean and Check for Leaks

Dirt and corrosion in the tank can contaminate the fuel and trigger petcock leaks. It’s essential to drain the fuel and clean the tank every time you clean the petcock. In addition, check for leaks at least once a week and address any issues before they get out of control.

Keeping the lever tight also goes a long way in preventing gas leaks through the petcock. The lever is prone to loosening over time, so check and tighten it regularly. Finally, inspect the petcock gasket for damage and replace it if necessary. That will keep your petcock leak free and your motorcycle pristine.

  • Keep the Spring Tight

Keeping the spring tight applies if you have a vacuum-operated petcock. The spring typically loosens over time and can impact the proper functioning of the float valve. To repair this, tighten the spring regularly to maintain your petcock and prevent costly issues.

  • Consider Upgrading the Component

If you’re restoring or repairing your motorcycle, it will help to also replace the petcock with a much better one. You’ll find many aftermarket parts that perform better than OEM parts. However, ensure you’re buying a quality product and avoid cheap parts. Upgrading the petcock during a rebuild could save you some headaches.

Can Fixing a Petcock Leak Solve the Issue of Water Coming Out of the Exhaust?

Fixing a petcock leak is not likely to solve the issue of water coming out of the exhaust. Common causes of water in exhaust include a blown head gasket, cracked engine block, or improper fuel combustion. It is crucial to address the root cause of the problem and seek professional assistance to diagnose and rectify the issue effectively.


Dealing with a leaking petcock on a motorcycle is easy after reading our comprehensive guide above. Here’s a recap:

  • Leaking fuel valves or petcocks can be repaired, although most, especially the rivet types, are made to be used once.
  • You can fix or buy a new petcock at most auto parts stores for a few bucks.
  • Once you’ve replaced the petcock, check and replace any other parts that could be worn out, such as fuel lines and hose clamps.
  • A leak, reduced engine performance, and a flooded engine are the most common signs you need a petcock replacement.
  • Keeping the petcock clean is one of the best ways to prevent it from failing prematurely.

You’re now informed enough to fix the leaking issue on your motorcycle petcock. Gather the tools you need and get it done or seek an expert’s help.

5/5 - (15 votes)
Ran When Parked