4-Stroke Engines

What event occurs before the end of the compression stroke?

A. ignition

In a breaker point ignition system, the breaker points open:

B. As primary voltage peaks

The stroke of an engine is determined by the:

B. Crankshaft

A customer complains of hard engine starting and poor performance. What tool could be used to determine the engine's condition?

B. Cylinder leakage tester

A broken compression ring is most likely caused by:

B. Detonation

For insert bearings, an excessive crush condition may be caused by:

B. Excessive torque applied to the bearing cap screws.

All fuel injection systems are electric.

B. False

Overheating of a liquid-cooled engine may be caused by:

C. Internal coolant flow blockage.

On an engine equipped with a carburetor, a bog or hesitation when accelerating from low to high speed could indicate:

D. Both A. and B. (Insufficient engine warm-up and Low speed mixture adjustment is too lean)

The optimum air/fuel ratio for a gasoline engine is:

A. 14.7:1

Vertical scratches on the piston may be caused by:

A. Abrasive ingestion

Excessive black exhaust smoke may be caused by:

A. Air filter element clogged

The timing of the opening and closing of the exhaust valve is regulated by the:

A. Camshaft

What is the most common type of fuel delivery method used to get fuel from the fuel tank to the EFI system?

A. Electric

Which of the following is not considered tampering by CARB and EPA?

A. Following the manufacturer's emission adjustment procedures.

Float bowl carburetors with a leaking fuel inlet needle will likely cause:

A. Hard starting, rough idling, or stalling

Which condition leads to an overheated catalytic muffler?

A. Lean carburetor

Insert bearings with dark discoloration and smearing of material may be caused by:

A. Oil starvation

An engine is equipped with an electronic governor. Technician A says this will make the engine more reliable because there are fewer moving parts. Technician B says this will make the engine more efficient because the engine can respond more quickly to changing load conditions. Who is correct?

A. Only Technician A

Technician A says that governor systems are not necessary for engine operation, but if they are used they will protect the engine from possible failure from overspeeding. Technician B says that most air-cooled engines are equipped with a governor to increase the horsepower potential of the engine. Who is correct?

A. Only Technician A.

What measuring tool would be used to measure the diameter of a valve stem?

A. Outside Micrometer

A large increase in elevation can cause a carburetor engine to run __________ if not properly adjusted for the altitude.

A. Rich

The ignition coil output voltage comes from:

A. The coil itself

The emissions warranty required by federal law covers emissions-related parts for ________ years.

A. Two

A piston damaged by overheating will show signs of:

A. and B. (Discoloration, and broken piston rings)

Detonation is caused by:

A. and B. (Pre-ignition and carbon deposits in the combustion chamber)

A spark plug with a cracked or broken insulator nose may have been caused by:

A. and C. (Foreign object in the combustion chamber and Detonation)

In a ball bearing a wear pattern in the non-rotating (usually the outer) race that is not parallel to the raceway edges may be caused by:

A. and C. (bearing misalignment and Loose-fitting bearing)

Fuel refined for use in a warmer climate will be less resistant to vapor lock.

B. False

The most common style of fuel filter for an EFI System is a reusable inline filter that can be washed and reused.

B. False

The owner of the equipment cannot be held responsible for tampering of emissions-controlled engines.

B. False

The throat of a carburetor should be the same diameter from one end to the other for best performance.

B. False

A localized wear area in an insert bearing may be caused by:

B. Foreign material lodged between the bearing outer surface and housing

A carburetor adjusted too lean causes:

B. Increased engine operating temperature

During the intake stroke, what are the positions of the valves?

B. Intake valve is open and exhaust valve is closed

Spark plug heat range is controlled by the:

B. Length of the insulator tip

With the addition of alcohol to gasoline and changes to the refinery processes, power equipment manufacturers do not recommend storing fuel for more than:

C. 30 days

The correct cylinder wall finish for properly seating new piston rings is:

C. 30 degrees to 45 degrees cross-hatch pattern

Pre-ignition is caused by:

C. A hot spot in the combustion chamber

What is used to ignite the air/fuel mixture inside the cylinder?

C. A spark plug

An engine is operating faster than the recommended speed. Technician A says one way to decrease the speed is to change the governor spring. Technician B says that the strength of the governor spring could be extended to decrease the speed. Who is correct?

C. Both technicians A and B

What state was the first state to regulate the emissions from lawn and garden equipment?

C. California

Oiled foam elements should be cleaned by:

C. Cleaning in hot soapy water, then drying.

As the density of the air diminishes, engines develop a ______________ condition.

C. Fuel-rich

One revolution of the crankshaft equals ___________ camshaft revolution(s).

C. Half

What stroke follows the exhaust stroke?

C. Intake

A dial indicator an be used for:

C. Measuring the run out of a crank shaft

The condenser:

C. Protects the points by reducing arcing.

Permeation requirements for the fuel tank, fuel feed lines, and fuel cap gasket is designed to:

C. Reduce hydrocarbon (HC) emissions

Hydraulic lifters:

C. Require no routine Maintenance

Which of the following could cause an engine to over-speed at full throttle?

C. Restricted fuel filter

What best describes the cause of the permanent breakdown of oil film strength?

C. Shearing of the oil layers

A magneto ignition system produces a spark when:

C. The primary circuit opens, inducing current in the secondary windings

An engine manufacturer requires head bolts to be tightened to a 11 lb-ft. What measuring tool would be used?

C. Torque wrench

Pistons and cylinders should be assembled:

C. With engine oil

In what year did the federal regulations for small engines take effect?

D. 1997

Carbon removal is important because it:

D. All of the above ( Restores horsepower, Helps engines to run cooler, reduces the risk of detonation)

Engine Knock can be caused by:

D. All of the above (Excessive carbon buildup in the combustion chamber, incorrect ignition timing, fuel with an octane rating below what is recommended for the engine.)

Dirty or debris filled cylinder fins can cause:

D. All of the above (Thermal decomposition in oil, Raised emissions, and Low heat transfer)

An engine that runs and then stops after a short period of time may be caused by:

D. All of the above. (An obstructed fuel tank vent, a defective ignition system, and bad fuel.)

Emission control parts include:

D. All of the above. (Carburetor, ignition module, air filter)

Which of the following may affect the operating temperature of an air-cooled engine?

D. All of the above: ( Engine oil quality/quantity, Spark plug heat range, Carburetor jetting)

Detonation may be caused by:

D. Both A and B. (Hot spots in the combustion chamber and Pre-ignition)

Using a spark plug with the incorrect heat range causes:

D. Both A and C. (Carbon deposits and Pre-ignition)

A spark plug with a white insulator and eroded electrode indicates:

D. Both B and C (Lean running engine and hot running engine)

Carburetor adjustments should be performed:

D. Both B and C (With clean air and fuel filters and When the engine is at operating temperature)

In a CDI system the ________ is charged by the exciter coil.

D. Capacitor

A four-stroke engine converts:

D. Chemical energy to mechanical energy.

Soft, black soot deposits on a spark plug may be caused by:

D. Improper fuel/air mixture (too rich)

Higher octane fuel burns:

D. None of the above

A cylinder bore gauge is used to check:

D. Roundness and taper

Two functions of piston rings are to:

D. Transfer heat from the piston to the cylinder wall and hold in combustion pressure

An electronic engine speed sensor within a governor system is connected to the:

Engine control unit (ECU)

Good governor control is necessary on an engine used to power an electric generator, because the voltage must not vary. The governor is supplying electrical energy to two electric motors and then two additional motors are turned on. Technician A says that the additional motors will cause the governor to speed up the engine in order to maintain the desired voltage. Technician B says that the governor will open up the throttle farther to account for the additional load. WHo is correct?

B. Only technician B

What phase of the federal regulations required a program of certification and assembly line testing?

B. Phase 2

A piston with a hole melted through the crown was probably caused by:

B. Pre-ignition

A capacitor dischrage ignition (CDI) equipped four-stroke engine has spark, good compression, and a properly operating fuel-delivery system but will not start. Which of the following is most likely the problem?

B. Sheared flywheel key

In a CDI system the ________ is triggered, creating a path to ground through a coil.

B. Silicone controlled rectifier (SCR)

In a two-cylinder, four-stroke engine, how many power strokes will occur in two rotations of the crankshaft?

B. Two

To complete one power cycle of the crankshaft, a four stroke engine must rotate:

B. Two revolutions

Gasoline is at its most flammable when it is in a :

B. Vapor

Light gray ash deposits on a spark plug may be caused by:

B. Worn valve guides

What is the fine for anyone found guilty of tampering with an emissions-controlled engine (per tampering act, per engine)?

C. $37,500

Most small engine manufacturers recommend not running fuel with an ethanol content of:

C. 10%

For proper high-speed operation, the ignition spark should occur:

C. 15 to 30 degrees before top dead center