How to Free a Seized Motorcycle Engine

What You'll Need
Spark-plug wrench
Penetrating oil
Motor oil
Terry-cloth rag
Blunt instrument
Brake fluid
1-foot copper wire
Hammer or mallet

A motorcycle engine that uses inferior- or low-quality engine oil may be prone to engine seizure. A common misconception among motorcycle enthusiasts is that the pistons expanding in size from high temperatures causes engine seizure. However, an insufficient amount of lubrication inside of the engine is what causes the issue. In addition, rust, from prolonged storage, could corrode the piston. No matter what caused your bike's engine to seize, here are a few remedies that will free it.

Step 1 – Prepare Your Bike

Before beginning, make sure that your bike engine is cool. Then, remove the spark plug by using a spark-plug wrench. Now is also a good time to clean or replace your spark plugs if need be.

Step 2 – Lubricate the Spark-Plug Hole

Next, spray a liberal amount of penetrating oil on the spark-plug hole to help lubricate the piston and melt away rust or dirt inside the cylinder wall. Let it stand for one hour.

Step 3 – Turn the Engine Over

At this point, the piston may be lubricated well enough to move. However, if you have the time, you may apply more lubricating oil and let it stand overnight before attempting to run the engine. Then, try to start the engine by using the kick starter to turn the engine, or use a wrench to turn the crankshaft bolt.

If the engine starts, the piston is free. If the engine fails to start, proceed to the next step. Do not overexert the kick starter on a seized engine.

Step 4 – Open the Engine Crankcase

Split the crankcase open if the engine fails to turn after applying the lubricating oil. To find and open it, consult an engine manual specific to your motorcycle’s make and model.

Step 5 – Clean the Area

Once open, you may find a lot of grime and dirt inside the cylinder and on top of the piston. Clean the surrounding area with a terry-cloth rag dipped in motor oil. You can use a blunt instrument to scrape rust off the gap between the piston and cylinder wall.

Then, pour a small amount of vinegar inside the cylinder. The acid will help neutralize dirt and condition the metal. Mix penetrating oil with a substantial amount of brake fluid and pour it on top of the piston, and let that stand for 10-15 minutes.

Step 6 – Prepare and Use the Copper Wire

Prepare a length of 1-foot copper wire, cut to size. Pound the tip on one end with a hammer or mallet to produce a paper-thin flat-shaped instrument.

Use this end to slide between the piston and cylinder wall to help the cleaning solution penetrate the point of seizure. Work the copper wire around the area of the piston and cylinder wall. You may apply more penetrating oil mixed with brake fluid if you need to.

Step 7 – Turn the Engine

Use a wrench to turn the crankshaft bolt and free the engine. For extreme cases of engine seizure, you may need to use multiple cranks. If it still isn't working, consider hiring a professional or begin calculating prices for an engine rebuild.