How To Clean Cast Aluminum Motorcycle Engine?

Cast aluminum can make for a nice-looking motorcycle engine. But one thing that cast aluminum is not so good at is staying clean. A layer of varnish and carbon deposits will eventually form if you don’t give your engine a quick cleaning every once in a while. 

This causes your bike to lose power and look bad among other things. So it’s very important to keep your bike engine clean in order to restore it back to factory condition.

In this article, we’ll explain the best way to clean aluminum engine in detail.

What Is The Black Residue On Aluminum?

The black residue on aluminum is a corrosion product called aluminum oxide. You should clean it off as soon as possible. Else, it will continue to build up over time until there’s so much buildup that you can no longer remove it without damaging what lies beneath.

What Is The Black Residue On Aluminum

Aluminum oxide is not soluble in water, so water will not get rid of it. If you want to clean the residue, you need to use a solvent that is miscible with aluminum oxide.

How To Clean Cast Aluminum Motorcycle Engine?

You can clean oxidized aluminum motorcycle engine cover and parts using two methods:

How To Clean Cast Aluminum Motorcycle Engine
  • Oxidation removal product (Mag Wheel Cleaner)
  • Cast blasting 

Method 1: Using an oxidation removal product

Step 1: Wash all parts with a damp cloth and a gentle detergent. Ensure to use a wire brush to reach the crevices on the cooling fins. However, don’t brush too hard to leave scratches on the surface. Rinse off with water. 

Using an oxidation removal product

Step 2: Spray the entire surface of the engine with Mag Wheel aluminum engine cleaner – a product that removes corrosion, dust staining, and rust. Apply to all exterior surfaces of the engine block and cylinder head. Pay extra attention to bolt threads, gasket mating surfaces, piston rings, and cylinder walls. Allow it to soak for 15-30 minutes.

Step 3: Scrub with a toothbrush or soft-bristled brush, focusing more on rust areas. Then rinse off with a high-pressure water hose and dry with a towel.

Step 4: Polish with a buffing wheel and polishing compound.

Method 2: Cast blasting (Bead blasting)

Cast blasting is a method that works very well for removing aluminum engine corrosion. It involves blasting media against the cast aluminum engine to remove the dirt. This method is not only effective but can also reduce your cleaning time significantly.

There are three blasting techniques for cleaning cast aluminum engine parts:

Sand blasting tends to be faster. However, it’s a bit aggressive, especially for thinner aluminum finishes. 

Cast blasting

Glass bead blasting and baking soda are gentle on cast aluminum, with the latter being more cost-effective. 

However, glass beads reward you with a more polished look than soda blasting. And this is typically the end goal you’re looking for.

Here, I am describing the bead blasting technique-

Step 1: Strip your motorcycle and remove the engine covers. Take off all the fittings and carburetor from the engine.

Step 2: With clean, dry rags, wipe down the engine thoroughly to remove any dust or debris. Let it air dry for 30 minutes. If there is any debris still on the surface of the engine (like oil or grease), use a spray lightly with WD40 engine degreaser to spot clean it.

Step 3: Once you’ve prepared the surface of your cast aluminum, it’s time to get started bead blasting. You’ll then want to set up the air compressor so that it’s blowing at the proper pressure for your beads. This will vary slightly depending on what type of beads you’re using and how large they are.

If you’re working with a medium-sized piece, like one that’s around 0.75 inches in diameter or less, then a medium-sized air compressor should be sufficient; however, if your piece is larger than that (e.g., 1 inch), then consider getting an industrial-size one instead!

Step 4: Now turn on both machines: 

For a siphon blaster or direct pressure blaster, adjust the air pressure to about 65 psi for best results. That air pressure will help move the beads around and create perfect coverage across all of your parts. 

If you are using a pressure pot, it is best to use an air compressor set at 40 psi because the size of the pot can affect how much force is needed to move the beads around inside it.

Step 5: Adjust your nozzle according to the size of your part that needs blasting and start blasting! Move it around until your part is covered in beads and has an even finish across all of its surfaces.

Step 6: Protect the cleaned surface by using a good sealer or a clear coating like epoxy. This will prevent dirt and corrosion from settling in again on the aluminum engine casings.

Can You Use Baking Soda And Vinegar On Aluminum?

You can use baking soda and vinegar on aluminum, but it must be done with care to avoid damage. This process will also leave a residue if it is not removed promptly after cleaning. So take that into consideration when deciding whether or not this method is right for you. 

Can You Use Baking Soda And Vinegar On Aluminum

One of the best ways is by using white vinegar mixed with water and then sprayed onto the surface using a spray bottle. This will dissolve any grease or dirt buildup without damaging any of the metal parts.

Cleaning cast aluminum with Vinegar and baking soda

Before you get started, make sure that the engine is cold so that the chemicals you’ll use do not burn off.

Cleaning cast aluminum with Vinegar and baking soda

Step 1: To begin, take a damp paper towel and wipe down any dust or dirt on the surface of your engine. You may also use a water-based cleanser to remove any grease or oil stains.

Step 2: Make a mixture of one part vinegar to four parts water. Apply this mixture by spraying it on the cast aluminum surface with a spray bottle. The vinegar naturally breaks down grease without causing harm to metal surfaces.

Step 3: Rinse off the vinegar solution and allow it to dry completely before moving on to the next step. This ensures that any residue from cleaning chemicals remains on top rather than sinking into crevices where it could cause damage over time due to corrosion!

Step 4: Wet a toothbrush and shake out excess water. Then dip it into a small container of baking soda, and scrub the cast aluminum engine with it. Rinse off the baking soda and allow the aluminum to air dry.

Step 5: When dry, use some of your aluminum polish to buff them to a shine!

Tips and Tricks For Cleaning Cast Aluminum Motorcycle Engine 

Tips and Tricks For Cleaning Cast Aluminum Motorcycle Engine
  • Use a soap/detergent-based degreaser for cleaning inside parts of the engine
  • Clean the engine only when it is cool
  • Check for any cracked parts, leaks, or broken parts. If any, repair by welding.
  • Remove the spark plugs and radiator cap before cleaning
  • Drain excess oil and coolant from the engine
  • Remove any covers or accessories attached to the engine
  • After cleaning, you must reapply a thin coat of oil to your bare engine in order to prevent rust from forming.


Cleaning your cast aluminum motorcycle engine is not that hard. But it is important that you do it right. 

These tips will help you clean your cast aluminum motorcycle engine without damaging it. All it takes is a little knowledge, some time, and the right materials.

Well, it may not be the most glamorous part of owning a motorcycle. However, it is necessary to help your bike run optimally and look its best.

For an even better cleaning experience, ensure your bike gets adequate maintenance in between cleanings.

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