Classic Motorcycle Build

Clean Carbon Off Cylinder Heads

Article by Vintage Vinny

There are many methods to clean carbon off cylinder heads, including soda blasting, media blasting, vapor blasting, walnut shell blasting, etc. But for the DIYer, there's still the old school way.

clean carbon off motorcycle head

Cleaning cylinder heads can still be effectively done by hand, using a spray or liquid degreaser, a brass cleaning brush, a little Emery cloth, and a lot of scrubbing. It will take longer than modern methods, but results will be the same.

DIY motorcycle cylinder head cleaning

Cleaning Aluminum Heads

Aluminum heads, like this one from a Norton Commando, can be made to look as good as new. However, caution must be taken not to scratch the aluminum alloy material--do not use steel scrapers or a screwdriver blade!

To determine what kind of material your cylinder head is made out of, stick a magnet to it. A magnet will stick to cast iron but not to aluminum.


CAUTION: On aluminum heads, power tools can really do more harm than good. Roloc discs should be used sparingly and only on the heavy stuff.


As you can see from the picture below, the engine that this head came off of was running too rich, which left the valves and ports coated with black carbon.

vintage motorcycle cylinder head cleaning

Getting Started

You'll need a valve spring compressor to remove and install valves and valve springs.

valve spring compressor tool for motorcycle engine

The tool in the picture was designed to fit Harley Big-Twins and Sportsters, but it's really a universal tool.

An old baking pan will hold most motorcycle cylinder heads. This one is 10" x 14" (it's also an oil change drain pan).

remove carbon deposits from aluminum cylinder head

Any gasket remnants can be carefully removed with a fresh razor blade.

Best Degreaser For Engine Parts

There are many good degreasers out there (Purple Power, POR-15, Spray 9, Super Clean, etc). For this head cleaning, I chose Purple Power in a Spray.

Let The Degreaser Soak

With pieces of wood, I propped up the head so that the ports would be horizontal. Then I sprayed degreaser into the ports and let it soak the heavy stuff for a while. The longer you let it soak, the easier it will be to remove.

DIY clean motorcycle engine parts

If you give the degreaser time to work, the carbon deposits will come off easily with a wire brush (brass brush for aluminum heads). For hard-to-get areas, a smaller parts cleaning brush or an old toothbrush can be used.

clean carbon deposits on motorcycle head

On stubborn, built-up areas, sand lightly with small squares of Emery cloth folded over.

If needed, final sanding can be done with 400 or 600 grit wet/dry paper.


Cleaning Carbon Off Valves

There are a several methods to remove carbon off engine valves. Thick carbon deposits can be removed on a bench grinder with wire wheel attachment.

bench grinder with wire wheel attachment

TIP: Head bolts can also cleaned on a bench grinder with wire wheel attachment.

After the heavy stuff is removed, I wrap some masking tape around the valve stem, and chuck the valve in my drill press, lightly sanding with progressively finer steel wool.

best way to clean removed engine valves

The same results can be gotten with a hand-held drill mounted in a work bench vice.


Rinse With Running Water

After cleaning/degreasing the head, rinse well with water. For those without a sink in their garage, an outdoor water faucet works just as well.

After a thorough rinsing, blow-dry all ports, fins, and openings with compressed air.

remove carbon off motorcycle engine head

50 year-old Norton Commando head ready for assembly.


As an alternative to vapor blasting, cleaning carbon off cylinder heads with degreaser will guarantee every inch of the head is gone over. And you don't have to ship it out and wait weeks or months for it to come back.


Related Articles:

Motorcycle Valve Job
How To Remove Valve Guides And Measure Guide Wear
How To Install Valve Guides
What Is A Three-Angle Valve Job?
Norton Commando Cylinder Head Removal
Repair Stripped Threads In Aluminum