Why Are My Motorcycle Exhausts Turning Yellow?

This article talks about why motorcycle exhausts turn yellow, how you can remove the yellowing effect, and what you can do to prevent it. 

Motorcycle exhausts get hot. Like, really, really hot. All of those high-temperature exhaust gasses moving at high velocity have different reactions with the metal surface. One of the most common reactions is the discoloration of the exhaust. 

And while discoloration can range from yellow and green to blue or purple, we focus on the yellow discoloration of motorcycle exhausts. 

After riding and working on motorcycles for the better part of two decades, we can safely say that we know a thing or two about what makes them tick. 

Keep reading to figure out a solution for your yellow exhaust problem. 

Why Do Motorcycle Exhausts Turn Yellow?

First, let’s figure out what causes this yellowing phenomenon in motorcycle exhausts. 

Discoloration of metal and motorcycle exhaust gasses go hand in hand. The extremely high temperatures of exhaust gasses cause specific chemical reactions inside the exhaust, and discoloration is just a visible symptom. 

The extremely hot exhaust gasses cause the surface of the metal to oxidize and form a visible layer on the outside. This is the yellowing effect. 

Yellowing on only one exhaust header pipe

If you noticed only the rear header on a twin-cylinder motorcycle turning yellow, don’t worry. In most twin-cylinder motorcycles such as Harleys, one of the cylinders is mounted behind the other. 

Add to that the fact that most of these bikes are air-cooled, and it makes sense that the rear cylinder would run a bit hotter than the one upfront. 

What you have to understand about the discoloration of motorcycle exhausts is that it works on a spectrum. And the yellowing effect that has you so concerned is just the beginning! 

Yellowing headers result from exhaust temperatures at about 450 F or less. This is considered downright cool in the motorcycle industry. You will see even more discoloration, from yellow to gold to blue, once temperatures hit 480 F or above. 

Are yellowing exhausts harmful to a motorcycle?

Not really. In most cases, a little bit of discoloration is perfectly normal and expected. A discoloring motorcycle exhaust is a sign of a bike that actually gets ridden, which can never be wrong. 

If you notice rapid, heavy discoloration of the exhaust, it could signal an issue with the motorcycle’s air-fuel ratio. You can find out more about that in this article. 

How to Prevent A Motorcycle Exhaust From Turning Yellow?

You won’t like the answer to that question. The only way to prevent your motorcycle exhaust from turning yellow is to stop riding it. Just park it in the garage, cover it up and never take it out again. 

That’s because the yellowing of motorcycle exhausts is a perfectly normal thing and something that will keep happening as long as you keep riding. 

Below, we have outlined a few ways to remove the yellowing effect from your motorcycle’s exhaust. Just know that none of these methods is permanent, and the discoloration will return if you ride the bike regularly. 

One effective method of preventing a motorcycle exhaust from turning yellow is to get the exhaust powder coated or painted. However, doing so means you don’t have a chrome exhaust anymore, which is counterintuitive. 

How Can I Get Rid of the Yellow on my Motorcycle Exhaust?

If the discoloration of your motorcycle exhaust concerns you that much, there are a couple of things you can try. Some of these methods remove the yellowing effect, while others use a ‘sweep it under the rug’ approach. 

1. Use Blue-Job chrome polish

Blue-Job is a unique chrome polish specifically designed to remove the bluing effect from your motorcycle exhaust. It works just as well for other discoloration such as yellow or gold. 

It works like pretty much any other chrome polish. Just dampen the included microfiber cloth and cover it with a healthy amount of polish. Remember that this chrome polish is a concentrate, so you shouldn’t need that much. 

Apply it on all of the yellow-ed areas of the exhaust, using back and forth motions. Depending on the severity of the discoloration, you may need to do multiple passes. Moreover, you will have to rub pretty hard for the polish to work, so really put some effort into it. 

If the discoloration has been removed to your satisfaction, wipe away any excess polish with the included Pipe-Wipes, and you should have a shiny chrome exhaust again. 

Again, you will have to keep repeating this process every time the exhaust discolors, so keep that in mind. 

2. Use oven cleaner

If you’re on a budget, an oven cleaner may be the answer to your problems. This method does require the motorcycle exhausts to be slightly warm to work correctly. So feel free to go for a quick ride around the block first. 

Now, spray the oven cleaner liberally over the affected areas. Make sure you cover all of the discolored yellow patches. Next, use a microfiber to work in the oven cleaner. Be careful you don’t burn yourself! 

You may have to leave the oven cleaner on for a few minutes to let it work properly. And expect to have to do multiple passes for gleaming chrome. Wipe away any excess product with a clean rag, and you’re just about done. 

3. Alfoil

If you don’t have an oven, you probably don’t have oven cleaner. Thankfully, another common kitchen article can get rid of the yellow on a motorcycle exhaust. 

Start by tearing off a piece of aluminum foil. How much, you ask? Anywhere from a few inches to the whole roll. Whatever works best for you. Next, crumple it all up into a ball and wet it thoroughly. While we recommend using water, some people swear by Coke. 

The water and Coke are just there to lubricate the buffing process. In reality, it is a chemical reaction between the metal surfaces that removes the yellow from a motorcycle exhaust. Something like WD-40 would be just as effective. 

Rub the alfoil over the affected areas using back and forth motions. Once you start to feel the surface becoming smooth, you can check if the yellow has been removed. Again, multiple passes may be required. 

4. Wrap your exhaust

As the saying goes, ‘Out of sight, out of mind.’ If the appearance of yellow on your exhaust has you that worked up, wrap the exhaust! 

You can find hundreds of different exhaust wraps, each of which will work to hide the yellow discoloration on the chrome pipes. This method also has the benefit of reducing heat coming off the exhaust. And take our word for it. Long rides are significantly more comfortable with exhaust wraps installed! 

5. Replace the exhaust

This is the most expensive and hard-to-do option on this list. We recommend waiting until your motorcycle exhaust is at least blue before replacing it but to each his own. 

This option also allows you to get an exhaust made of higher quality materials that will resist discoloring for longer. A new exhaust will give you better sound and possibly more power too. 

Conclusion

So there you have it, a few methods for removing the yellow from your motorcycle exhaust. We must reiterate that none of these methods is perfect, and the yellowing will return over time. 

Furthermore, the yellowing of an exhaust is perfectly normal and nothing that should concern you. And maybe the best way to ‘remove’ yellowing from an exhaust is to keep looking forward while riding your motorcycle!

Author
Higgins Cooper1

Hi, I'm Hugo, I'm a motorcycle enthusiast who’s been riding for the last 10 years. I'm passionate about all things motorcycles and started Bikes Future to help other riders make the right motorcycle moves. I ride a white Kawasaki Ninja 400, and enjoy adventure riding on country roads when I get the chance.