Yamaha Blaster Engine Break In Procedure

A proper Yamaha Blaster engine break in allows the new piston rings to seat against the freshly bored or honed cylinder. It also lets the piston, cylinder, bearings and gaskets go through their first controlled heating and cooling cycles.

Follow this procedure after installing a new piston and rings or completing a full Yamaha Blaster engine rebuild.

Before Starting the Engine

Before starting a freshly rebuilt Yamaha Blaster:

• Perform a two-stroke leak-down test. Ken OConnor Racing performs a leak down test on every engine before it ships.
• Verify that the carburetor jetting is correct.
• Fill the transmission with the correct oil.
• Use fresh fuel and high-quality two-stroke oil.
• Use a 32:1 premix ratio if the oil-injection system has been removed.
• Make sure the air filter is clean and properly oiled.
• Check all fasteners, clamps and fluid levels.

Do not start the break-in process if the engine has an air leak or questionable jetting. Either condition can quickly damage a new piston and cylinder.

Perform Three Stationary Heat Cycles

The Yamaha Blaster should not be ridden during the three initial heat cycles.

Place the Blaster in a safe, well-ventilated area. Never run an engine inside a closed building.

Heat Cycle 1

Start the engine and bring it up to normal operating temperature. An infrared heat gun works well to monitor temperatures.

Do not leave the engine unattended or hold it at one constant RPM. Occasionally vary the engine speed gently, but do not rev the engine excessively.

Once the engine reaches normal operating temperature, shut it off and allow it to cool completely.

Heat Cycle 2

After the engine has completely cooled, start it again.

Bring the engine back up to normal operating temperature while occasionally varying the RPM. Shut it off and allow it to cool completely.

Heat Cycle 3

Repeat the same procedure one final time:

Inspect the Engine After the Heat Cycles

After the third heat cycle and a complete cool-down:

• Check for fuel, oil, intake and exhaust leaks.
• Inspect the spark plug.
• Check the transmission oil level.
• Inspect the carburetor and intake clamps.
• Check cylinder head and base nuts using the correct torque specifications.

Always check fastener torque when the engine is completely cold. Never exceed the specified torque value.

First Ride After Rebuilding

After completing all three stationary heat cycles, the Yamaha Blaster can be ridden normally.

Vary the engine speed and avoid lugging the engine in a high gear. Always allow the engine to warm up before placing it under a heavy load.

Do not use sustained wide-open throttle during the first half tank of fuel.

Short periods of heavier acceleration are acceptable after the engine is completely warm. The important restriction is to avoid holding the throttle wide open for an extended period during the first half tank.

After the first half tank, allow the engine to cool completely and inspect it again for leaks or loose components.

Yamaha Blaster Break-In Checklist

Before Starting

• Perform a leak-down test
• Confirm safe carburetor jetting
• Use fresh fuel
• Use quality two-stroke oil
• Mix premix at 32:1, if applicable
• Check the transmission oil
• Clean and oil the air filter
• Check all fasteners and clamps

Break-In Procedure

• Complete the first stationary heat cycle
• Allow the engine to cool completely
• Complete the second stationary heat cycle
• Allow the engine to cool completely
• Complete the third stationary heat cycle
• Allow the engine to cool completely
• Inspect the engine
• Recheck appropriate fasteners when cold
• Avoid sustained wide-open throttle for the first half tank

Important Break-In Reminders

• Do not ride the Blaster during the initial three heat cycles.
• Allow the engine to cool completely between cycles.
• Do not leave a running engine unattended.
• Do not excessively rev a fresh engine.
• Use the same premix ratio during and after break-in.
• Warm the engine before riding hard.
• Avoid sustained wide-open throttle during the first half tank.
• Stop immediately if the engine overheats, loses power or makes abnormal noises.

Need Help With Your Yamaha Blaster Engine?

Ken OConnor Racing provides professional Yamaha Blaster engine rebuilding, cylinder boring, crankshaft rebuilding, porting, head work and complete engine machine-shop services.

Correct machine work, piston clearance, engine assembly, leak-down testing and carburetor jetting are critical to the performance and reliability of a rebuilt Yamaha Blaster engine.

Contact Ken OConnor Racing for professional Yamaha Blaster engine rebuilding and machine-shop services.

Frequently Asked Questions

How many heat cycles does a Yamaha Blaster need?

KOR recommends three complete heat cycles. Bring the engine up to normal operating temperature, shut it off and allow it to cool completely. Repeat this procedure two more times.

Should I ride the Blaster during the heat cycles?

No. The three initial heat cycles should be completed without riding the Blaster.

How long should I let the engine cool?

Allow the engine to cool completely before starting the next cycle. Do not restart it while the cylinder or head is still hot.

How should I ride after completing the heat cycles?

After completing the three heat cycles, the Blaster can be ridden normally. Avoid sustained wide-open throttle during the first half tank of fuel.

What premix ratio should I use during break-in?

Use 32:1 with high-quality two-stroke oil if the oil-injection system has been removed. Do not add extra oil for break-in.

Is a leak-down test necessary?

Yes. Perform a leak-down test before starting a rebuilt two-stroke engine. A break-in procedure cannot protect the engine from a leaking seal, gasket, intake or crankcase.