Riding a motorcycle with a rusty gas tank is a bad idea. The rust will damage the engine ultimately. First, it will ruin the fuel filters, the carb struggles next, the engine is the last stop. That’s why most people recommend replacing a rusty tank. But that isn’t always the case. The gas tank can be cleaned from rust, you just have to know how to do it. Let’s find out if your gas tank should be replaced, and how to clean it.
- Inspect the gas tank
- Evaluate damage
- Get cleaning supplies
- Empty and remove the tank
- Seal holes
- Add acid and abrasives
- Empty, wash and dry the tank
If your gas tank can be cleaned from rust, all you have to do is follow these steps. That is easier said than done though. There’s a lot more to expand on. Here’s a full guide on how to clean rust out of a motorcycle gas tank.
Inspecting The Tank
Now, let’s be real, this depends on the condition of your tank. I guess some of you noticed a small amount of rust and got worried. But some of you may have ignored the situations for quite a while. To the point that even the outside paint has rust spots. Either way, we can’t tell until we take a look.
Take a flashlight and a mirror. If you can duct tape the mirror on a stick, that would help a lot. Those that want to be thorough, get a borescope. Open the tank, light it up, and look for rust. If you’re lucky enough, you’ll only see rust spots. In worse situations, you’ll see a whole layer of rust.
So, how does it look? Assess the situation? Do you think it would be worth it to clean it up? In my opinion, as long as rust has not gotten through to the exterior of the tank, it can be cleaned. Keep in mind, many people opt for a replacement even if the tank can be cleaned.
Even if you can clean the tank, if it’s badly rusted, it’s going to take you a while. It’s a lot of effort, let’s just say that. While someone will clean the tank fairly easily, you are going to be cleaning the rust for a long time. All I’m saying is that you need to decide for yourself, is this worth it?
Should I Replace My Motorcycle Gas Tank
The rule of thumb is if rust broke through to the outside paint, you should replace the tank immediately. But as I said before, you assess the situation. In some cases, it’s better to replace it even if the paint is spotless.
Here’s the thing, there are plenty of options for a replacement fuel tank. Popular models that are widely used, have brand-new replacements available for order. But this can be quite expensive. A less expensive option is a used tank.
Don’t be wary of used tanks. If it’s been preserved and is considerably better than your current one, don’t think twice. With widely used bikes, there are a lot of used replacement parts available. So, consider that option.
Check mechanics, online ads, dealers, and used bike venues for a replacement tank.
In the end, you decide between cleaning and looking for a replacement part. It depends on your situation, if you’re lucky both ways are easy. Some bikes rarely have parts available, so cleaning is the only option. Keep in mind, looking for a replacement part can take a while too.
To sum up, a motorcycle tank should be replaced if there’s rust on the exterior of the tank. Otherwise, you’re the one who decides if the cleaning effort is worth it.
Fuel Tank Cleaning Supplies
- Plugs, vacuum caps, threaded fittings, stoppers
- Acids. Vinegar or acids dedicated for fuel tanks
- Abrasives. Nuts and bolts, BBs, gravel
- Flexible hollow tube
- Water hose
- Hair Dryer
- Bore Scope(Optional)
Empty Fuel And Remove Tank
You can’t work while the tank is installed in the bike, you need to remove it. I recommend emptying it first, to avoid any spillage. Do not empty the tank by riding until it’s empty. First of all, it’s dangerous to ride with a rusty tank. The fuel filter will collect as much as possible but that tiny piece will get through and enter the engine. Not to mention, you’ll have to replace the filters quite regularly.
Empty the tank by using a flexible hollow tube. Insert the tube inside the tank. Place a jerrycan under the other end of the tube. To start the flow, suck on the other end until fuel starts flowing. Be careful not to swallow it. There will be a strong scent of gasoline which may be unpleasant. You can wear a mask while doing this to avoid inhaling the gasoline.
Then, remove the tank. It’s a simple step to do, just unscrew the bolts and screws, and remove the fuel lines. Here’s a video on how to do that.
Seal The Holes
Since you’re going to fill the tank with vinegar, you’ll have to seal the holes in the tank. The basic tank design has a filling hole and a petcock hole. It depends on the model though, your bike may have up to 4 holes.
To avoid complications, I recommend getting a set of plugs, and vacuum caps. Get as many as possible in various sizes. You can find whole sets online, that should cover you for future tank cleanups.
Seal every hole in the tank except for the filler hole, the hole where you pour fresh fuel.
Fill With Acid
Rust is quite annoying, and the usual cleaning solutions for metal won’t do it. You need an acidic solution. I highly recommend using household vinegar, made from alcohol, usually known as white vinegar. Don’t use apple or wine vinegar.
Strong acids, or stronger acids than vinegar can be used but are not recommended. The thing is, you want to remove the rust but not damage the metal surface. Vinegar is a mild acid, the chances that it will damage the tank are low. Stronger acids can damage the tank, especially thin ones.
Before you pour the vinegar in, you’ll want to go outside. Find an outside working area where you won’t spill acid on other things. At least use a well-ventilated room, you don’t want to be breathing in chemicals.
Fill up the tank until it’s completely full. If you are using vinegar, you want to let it sit for a while before adding the abrasives. With muriatic acid, you want to be as fast as possible so it doesn’t damage the tank.
Now, if you’re not familiar with rust removal from metal, you may be confused by this. The easiest way to break apart those huge chunks of rust is with abrasives. The vinegar will take care of the rust particles.
Because you can’t use any chemicals on major metals, you will need alternative rust removers. Metal screws like lugs and nuts are the preferred choice. I have seen people using gravel, it’s quite effective. BBs are an option too. Anything will do, just get rid of those chunks of rust.
Don’t overdo it with the nuts. A handful or two will do. If you are worried about forgetting a piece, tie them onto a string. Or, just keep count of how many nuts you have used. Pour the abrasives into the tank, and cap the filler hole.
Your tank is prepared, now you need to shake it up, so the abrasives can do their thing. Pick up the tank and start shaking it as much as you can. Don’t tire yourself too much, if you’re using vinegar, you’ll be doing this for days. When done shaking, open the tank, see if the level of rust has decreased. You should at least see chunks and rust particles floating.
Repeat this is until you are satisfied with the rust level. Of course, with persistent rust, you’ll have to do this every day for an extended period of 8 days to 2-3 weeks. You can get creative in this step. If you can find a more efficient way for shaking, do it. Just don’t damage the tank.
Remember, if you’re using phosphoric acid or muriatic acid, adding the chemicals and shaking should be done as fast as possible.
Washing The Tank
Once you let the tank sit out, you’ll need to finish the process. This includes emptying the tank, flushing it, and letting it dry. Don’t give up now, you are nearly done.
Start by removing the seals you used. Empty the vinegar into an empty bucket. Be careful with the bucket you are using, make sure it can’t get damaged from the acids. Remove the abrasives too, make sure you get everything. Again, do this outside or in a well-ventilated area.
Then, you’ll want to “rinse” the tank. Pick up your water hose and start spraying inside the tank. Clean it thoroughly, make sure the pressure isn’t too high so you won’t damage the gas tank paint job. Stop when the vinegar is completely cleaned out.
Chances are, vinegar will still be present inside. There’s a way to treat this, with a homemade neutral solution. Again, seal up the holes, exactly like you did before. Warm-up 4-5 gallons of water. Don’t reach the boiling point, it should be hot but not boiling hot. Add kitchen soap to the tank and then add the hot water. The water and soap solution will dissolve any leftover vinegar.
Unseal the tank and empty it out again. You are done with the cleaning process, all you need to do is let it dry. To do that, use a hairdryer while also allowing for natural air to flow through the gas tank. Move quickly with the hairdryer and set it on low heat. Use your hands to check how hot the metal is.
You are basically done. Some people don’t stop here, they add fuel tank additives. These are meant for protection against rust reappearing. There are many gas tank treatment products out there, specifically called tank sealers. If you are interested check out a tank sealer kit.
Be careful though, a tank liner product can cause trouble with the carb. So, they don’t come recommended. Usually, this protective layer is added only to bikes that don’t have replacements available.
Related Questions And Other FAQs
What Causes Rust In Motorcycle Gas Tanks
Rust usually forms due to negligence from the owner. When the bike is inactive or the tank is never filled up, rust forms on the surface exposed to oxygen. Keep the tank filled up and add a fuel stabilizer in the winter to prevent rust.
Is Rust In Motorcycle Gas Tank Bad
Yes, rust is very bad for the bike. If it flows into the fuel lines and the engine, it may heat it up too much. It can also clog the fuel filter which will mess up with the fuel flow.
How Do I Keep My Gas Tank From Flashing Rusting After I Clean It
Flash rust can appear after cleaning the tank. It’s not that dangerous and it’s fine if you leave it like that. It’s a bit of surface rust, so you can’t really stop it. Some use a rust dissolver solution like naval jelly, although this is not recommended. Don’t worry about flash rust.