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Sri Lanka NVQ L3 Motorcycle Mechanic study materials
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Sri Lanka NVQ L3 Motorcycle Mechanic practice questions

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Question 1Workplace safety, health and environment

When lifting a motorcycle engine out of a frame in the workshop, which practice best protects your lower back?

  1. Hold your breath and jerk the engine upward quickly to reduce strain time
  2. Keep the load close, bend the knees, and get help or use a hoist for heavy units Correct answer.
  3. Bend at the waist and twist the torso to swing the engine clear
  4. Lift with arms fully extended so the engine stays away from your body

Explanation

Manual handling guidance requires keeping the load close to the body, bending the knees rather than the back, and avoiding twisting under load. Engines and complete wheels exceed safe single-person lifting limits, so a hoist or a second person should be used. These measures reduce compressive and shear forces on the lumbar spine.

Question 2Workplace safety, health and environment

Which type of fire extinguisher is the correct first choice for a small petrol fire on the workshop floor?

  1. Carbon dioxide extinguisher only
  2. Water stored-pressure extinguisher
  3. Wet chemical extinguisher
  4. Dry powder or foam (AFFF) extinguisher Correct answer.

Explanation

Petrol is a Class B flammable liquid fire, and dry powder or foam extinguishers are rated for this class. Foam also blankets the surface to stop vapour release. Water must never be used because it spreads the burning fuel.

Question 3Workplace safety, health and environment

A mechanic must drain used engine oil from a motorcycle. What is the correct environmental practice?

  1. Mix it with workshop rags and place it in the general refuse bin
  2. Store it in a labelled, lidded container and hand it to a licensed used-oil collector Correct answer.
  3. Pour it down the workshop drain with plenty of water to dilute it
  4. Spread it on the yard to suppress dust

Explanation

Used engine oil is hazardous waste containing heavy metals and hydrocarbons, so it must be segregated in labelled, closed containers and passed to an authorised recycler or collector. Diluting or dumping it contaminates soil and groundwater and breaches waste regulations.

Question 4Workplace safety, health and environment

Before starting work under a motorcycle raised on a hydraulic lift, what is the essential safety step?

  1. Lower the lift slightly so the wheels rest on the floor
  2. Place a jack under the sump as the only support
  3. Ask a colleague to hold the lift pedal down
  4. Engage the mechanical safety lock or support pins after raising Correct answer.

Explanation

A hydraulic lift relies on fluid pressure, which can fail through hose burst or seal leakage, so the mechanical safety lock must be engaged once the platform is at working height. This provides a positive, non-hydraulic restraint against sudden descent.

Question 5Workplace safety, health and environment

Which PPE is specifically required when grinding or wire-brushing metal components on a bench grinder?

  1. An apron only
  2. Leather gloves only
  3. A dust mask only
  4. Close-fitting impact goggles or a face shield over safety glasses Correct answer.

Explanation

Grinding and wire brushing throw high-velocity particles and broken wire filaments, so eye and face protection is the primary control. Impact-rated goggles or a face shield worn over safety spectacles protect against both direct and deflected fragments.

Question 6Workplace safety, health and environment

Why must a motorcycle engine never be run in a closed workshop without extraction?

  1. The noise level exceeds the permitted limit
  2. Exhaust gases contain carbon monoxide, an odourless gas that can cause unconsciousness Correct answer.
  3. The engine will overheat because of stale air
  4. Fuel consumption rises sharply indoors

Explanation

Petrol engine exhaust contains carbon monoxide, which binds to haemoglobin far more readily than oxygen and can cause headache, collapse and death in an enclosed space. Because it is colourless and odourless, workers receive no warning, so exhaust must be piped to outside or extracted at source.

Question 7Workplace safety, health and environment

A mechanic is about to use a two-post lift to raise a motorcycle for tyre replacement. Which check best confirms the machine is safely supported?

  1. Check that the lift arms contact the frame at the manufacturer's lifting points and the load is balanced Correct answer.
  2. Ensure the handlebars are turned fully to one side
  3. Confirm the tyres are inflated to the correct pressure
  4. Verify the fuel tank is more than half full

Explanation

Stability depends on the lifting points and centre of gravity, so the arms must engage the frame at the points specified by the manufacturer and the load must be balanced. An unbalanced or wrongly positioned machine can slide or tip once raised.

Question 8Workplace safety, health and environment

During a road test of a repaired motorcycle, which practice best manages risk to the rider and public?

  1. Ride without a helmet for a short distance so you can hear the engine clearly
  2. Carry a colleague on the pillion to observe the instruments
  3. Wear a helmet and protective clothing, use a planned route, and check brakes and controls before moving off Correct answer.
  4. Test at maximum speed to confirm the repair holds

Explanation

A road test is a work activity, so the rider must wear the same protective equipment as any rider and confirm brakes, steering and controls function before joining traffic. A planned, low-risk route keeps the test short and predictable.

Question 9Workplace safety, health and environment

A compressed-air blow gun is used to clean brake dust from a wheel hub. What is the safest method?

  1. Seal the area with plastic sheeting and blow the dust into it
  2. Blow the dust toward the open workshop door with maximum pressure
  3. Direct the jet at your overalls to clean them at the same time
  4. Use low pressure with extraction or a damp cloth, and wear a suitable respirator Correct answer.

Explanation

Brake dust may contain asbestos or other respirable fibres, so it must not be made airborne. Low-pressure air combined with local extraction or wet wiping, plus a suitable respirator, keeps exposure within limits. High-pressure blowing simply disperses the hazard throughout the workshop.

Question 10Workplace safety, health and environment

Which precaution is required before welding or brazing near a motorcycle fuel tank that has been drained?

  1. Fill the tank with water and weld with the filler cap open
  2. Weld immediately because the tank is empty
  3. Purge and ventilate the tank, remove it from the work area, and keep a fire extinguisher at hand Correct answer.
  4. Cover the tank with a cloth and continue

Explanation

A drained tank still contains flammable vapour, which is the explosive component, so it must be purged, ventilated and removed from the hot-work area. A fire extinguisher and a fire watch are standard hot-work controls.

Question 11Workplace safety, health and environment

When charging a lead-acid motorcycle battery in the workshop, which control is most important?

  1. Charge in a sealed cabinet to keep the acid vapour contained
  2. Charge next to an open flame to burn off the hydrogen
  3. Charge in a well-ventilated area away from sparks, with eye protection available Correct answer.
  4. Charge with the filler caps removed and the area closed off

Explanation

Lead-acid charging releases hydrogen, which is explosive in concentrations as low as four percent in air, so ventilation and ignition control are essential. Sulphuric acid mist and electrolyte also require eye protection and access to eyewash.

Question 12Workplace safety, health and environment

A mechanic notices a small hydraulic oil leak under a lift. What is the correct immediate action?

  1. Stop using the lift, isolate it, clean up the spill and report the defect for repair Correct answer.
  2. Continue working and clean the floor at the end of the shift
  3. Top up the reservoir and continue until the next service
  4. Place a rag over the leak and carry on

Explanation

A leaking lift is a defective piece of lifting equipment, so it must be taken out of service until repaired. The spill also creates a slip hazard that must be cleaned and the defect reported through the maintenance system.

Question 13Workplace safety, health and environment

Which statement correctly describes the purpose of a risk assessment for a motorcycle repair task?

  1. It identifies hazards, evaluates who may be harmed and how, and sets out controls before work starts Correct answer.
  2. It replaces the need for training and supervision
  3. It records the accidents that have already happened in the workshop
  4. It is a form completed only when an inspector visits

Explanation

A risk assessment is a proactive process that identifies hazards, evaluates the likelihood and severity of harm, and records the control measures to be applied. It must be done before the task and reviewed when conditions change.

Question 14Workplace safety, health and environment

A mechanic must remove a seized exhaust bolt using a penetrating fluid and heat. Which combination of controls is most appropriate?

  1. Apply heat first, then spray the fluid onto the hot bolt
  2. Spray the fluid continuously while heating to keep the bolt cool
  3. Apply the fluid, allow it to flash off, then heat with a fire extinguisher nearby and good ventilation Correct answer.
  4. Heat the bolt inside a closed plastic tent to retain the heat

Explanation

Penetrating fluids are flammable, so the solvent must be allowed to evaporate before any flame or induction heat is applied. Ventilation, a fire extinguisher and a fire watch are standard controls for combined chemical and hot-work hazards.

Question 15Workplace safety, health and environment

Which measure best controls the risk of hand-arm vibration syndrome for a mechanic using impact wrenches daily?

  1. Work through breaks to finish the job faster
  2. Use low-vibration tools, limit exposure time, and keep hands warm and relaxed between tasks Correct answer.
  3. Wear thick gloves and continue for the full shift
  4. Grip the tool as tightly as possible to reduce vibration transfer

Explanation

Hand-arm vibration exposure is managed by reducing the vibration magnitude at source, limiting trigger time and maintaining good circulation through warmth and relaxation. These measures align with the exposure action values used in vibration regulations.

Question 16Workplace safety, health and environment

A motorcycle is being stripped and the fuel tank must be stored in the workshop. Which storage arrangement is safest?

  1. Store it beside the battery charger to save space
  2. Store it on a high shelf above the workbench
  3. Store it with the filler cap removed on the floor near the door
  4. Store it in a designated flammable-liquids cabinet or drained and ventilated area away from ignition sources Correct answer.

Explanation

Fuel tanks contain flammable liquid and vapour, so they belong in a designated flammable-liquids store or must be drained and purged in a ventilated area away from ignition. This limits the fuel load available to a fire and prevents vapour accumulation.

Question 17Workplace safety, health and environment

What is the primary reason for connecting a workshop air compressor's pressure regulator to the tool's rated pressure?

  1. To prevent hose or tool failure and uncontrolled whipping from over-pressure Correct answer.
  2. To reduce electricity consumption of the compressor
  3. To keep the compressor from starting automatically
  4. To increase the torque output of air tools

Explanation

Air tools and hoses are rated for a maximum working pressure, and exceeding it can burst a hose or fitting and cause a violent whip. Regulating to the tool rating keeps the system within its design limits and protects the operator.

Question 18Workplace safety, health and environment

A mechanic is asked to degrease engine cases using a solvent in a parts washer. Which control most directly limits inhalation exposure?

  1. Work faster so the solvent has less time to evaporate
  2. Use the washer with its lid closed and local exhaust ventilation running Correct answer.
  3. Open all workshop doors and rely on natural draught
  4. Wear a dust mask while using the solvent

Explanation

Solvent vapour is the inhalation hazard, so containment and extraction at source are the most effective controls. A closed lid plus local exhaust ventilation captures vapour before it reaches the breathing zone.

Question 19Workplace safety, health and environment

A workshop uses a two-pack paint system containing isocyanates. Which control hierarchy application is most correct?

  1. Provide a dust mask and rely on the worker to keep exposure short
  2. Rely on the paint's low volatility to keep vapour levels safe
  3. Substitute with a non-isocyanate system where feasible, and where not, use a spray booth with extraction and air-fed respiratory protection Correct answer.
  4. Spray in the open workshop with the doors closed to keep dust out

Explanation

Isocyanates are potent respiratory sensitisers, so the hierarchy of control starts with elimination or substitution of the product. Where two-pack paint must be used, engineering controls such as a spray booth and air-fed respiratory protection are required because the health effect can occur at low exposure.

Question 20Workplace safety, health and environment

An apprentice reports a tingling sensation and whitening of the fingers after prolonged use of a needle scaler. What is the most appropriate response?

  1. Record the symptoms, remove or reduce the vibrating task, refer for health assessment and review exposure controls Correct answer.
  2. Move the apprentice to a different department without recording the case
  3. Recommend warmer gloves and no other change
  4. Advise the apprentice to continue and report back if symptoms worsen

Explanation

Tingling and blanching of the fingers are early signs of hand-arm vibration syndrome, a reportable occupational condition. The correct response is to record the symptoms, reduce or stop exposure, arrange a health assessment and review the controls that allowed the exposure.

Question 21Hand tools, measuring instruments and workshop equipment

When tightening a cylinder head cover bolt to a small torque value on a motorcycle engine, which tool gives the most accurate and repeatable tightening force?

  1. An impact driver with a socket adapter
  2. A standard combination spanner pulled by feel
  3. A T-handle socket driver turned until it stops
  4. A click-type torque wrench set to the specified value Correct answer.

Explanation

A click-type torque wrench is calibrated to release a signal at a set torque, so the fastener receives the value stated in the workshop manual. Tightening by feel or until the tool stops gives no measurable control and risks stripping threads in aluminium castings. Impact tools deliver uncontrolled torque and are unsuitable for small cover bolts.

Question 22Hand tools, measuring instruments and workshop equipment

The vernier scale on a 0.02 mm resolution vernier caliper has 50 divisions. What measurement does the reading represent when the main scale shows 12 mm and the 23rd vernier line coincides with a main scale line?

  1. 12.023 mm
  2. 12.46 mm Correct answer.
  3. 12.50 mm
  4. 12.23 mm

Explanation

Each vernier division equals 0.02 mm, so the 23rd coinciding line adds 23 × 0.02 = 0.46 mm to the main scale reading. The total is therefore 12.46 mm. Reading the vernier number directly as hundredths is a common mistake that produces 12.23 mm.

Question 23Hand tools, measuring instruments and workshop equipment

A micrometer screw gauge has a 0.5 mm pitch and a thimble with 50 divisions. What is the least count of the instrument?

  1. 0.02 mm
  2. 0.10 mm
  3. 0.05 mm
  4. 0.01 mm Correct answer.

Explanation

Least count equals pitch divided by the number of thimble divisions, so 0.5 mm ÷ 50 = 0.01 mm. This is why micrometer readings are quoted to two decimal places. A 0.02 mm least count belongs to a standard vernier caliper, not this micrometer.

Question 24Hand tools, measuring instruments and workshop equipment

Before using a dial bore gauge to check cylinder wear, what is the correct first step?

  1. Zero the gauge against an outside micrometer set to the nominal bore size Correct answer.
  2. Insert the gauge into the bore and read the needle directly
  3. Oil the bore heavily so the plunger slides without friction
  4. Set the dial bezel to zero while the gauge hangs free in air

Explanation

A dial bore gauge is a comparator, so it must be zeroed against a known dimension, normally an outside micrometer set to the nominal bore. Only then does the needle deflection represent actual deviation from that size. Zeroing in free air or reading without a reference gives no meaningful measurement.

Question 25Hand tools, measuring instruments and workshop equipment

Which measuring instrument is most suitable for checking the outside diameter of a valve stem to verify wear against the service limit?

  1. Steel rule
  2. Feeler gauge
  3. Outside micrometer Correct answer.
  4. Plastigauge

Explanation

An outside micrometer measures small external diameters to 0.01 mm, which suits the tight tolerance on a valve stem. Feeler gauges measure gaps, plastigauge measures bearing clearance, and a steel rule resolves only about 0.5 mm. None of those alternatives can confirm valve stem wear against a limit given in hundredths of a millimetre.

Question 26Hand tools, measuring instruments and workshop equipment

A feeler gauge is being used to check valve clearance on a four-stroke engine. What does the correct procedure require?

  1. The blade should slide with slight drag at the specified clearance when the engine is cold Correct answer.
  2. The thickest blade that can be forced in should be recorded as the clearance
  3. The blade should pass freely with no contact at all
  4. The measurement should be taken with the engine at full operating temperature only

Explanation

Valve clearances are specified cold for most air-cooled motorcycle engines, and the correct blade should enter with a light, even drag. A blade that will not enter means the gap is too small, while one that passes with no contact means the gap is too large. Forcing a thicker blade distorts the reading and can damage the rocker or valve tip.

Question 27Hand tools, measuring instruments and workshop equipment

What is the primary purpose of using a piston ring compressor during engine assembly?

  1. To expand the ring so it seats against the bore
  2. To align the connecting rod with the crankshaft journal
  3. To measure ring end gap before installation
  4. To compress the rings so the piston enters the cylinder without breaking a ring Correct answer.

Explanation

A ring compressor tapers the rings into their grooves so the piston can slide into the cylinder bore without a ring catching on the lip and cracking. It does not measure anything and does not align the rod. Ring end gap is checked separately with the ring squared in the bore using a feeler gauge.

Question 28Hand tools, measuring instruments and workshop equipment

A bench vice is being used to hold an aluminium engine cover for drilling. Which practice protects the workpiece and the operator?

  1. Fit soft jaws and clamp the cover so the drill axis is clear of the vice body Correct answer.
  2. Hold the cover by hand against the vice jaw face
  3. Clamp the cover with serrated jaws tightened as hard as possible
  4. Support the cover on wooden blocks without clamping

Explanation

Soft jaws spread the clamping load and prevent the serrated steel jaws from marking or crushing the aluminium casting. The workpiece must also be positioned so the drill cannot pass into the vice body. Hand holding or loose support allows the part to spin or lift when the drill bites.

Question 29Hand tools, measuring instruments and workshop equipment

Which tool is designed specifically to remove and install a flywheel from a motorcycle crankshaft without damaging the taper?

  1. Flywheel puller matched to the thread and taper Correct answer.
  2. Two-jaw gear puller gripping the flywheel rim
  3. Adjustable wrench on the flywheel nut
  4. Cold chisel and hammer applied to the rim

Explanation

A dedicated flywheel puller screws into the flywheel centre thread and pushes on the crankshaft end, drawing the taper apart evenly. Gripping the rim with a gear puller or striking the flywheel can bend it and damage the crank. The flywheel nut is removed first, but the wrench alone cannot separate the taper.

Question 30Hand tools, measuring instruments and workshop equipment

A click-type torque wrench has been dropped on the workshop floor. What is the correct action before returning it to service?

  1. Continue using it because the click mechanism is sealed
  2. Have it recalibrated and verified against a torque tester Correct answer.
  3. Oil the internal mechanism and store it at maximum setting
  4. Adjust the setting screw by one quarter turn to compensate

Explanation

A drop can alter calibration without any visible damage, so the wrench must be checked against a torque tester before use on critical fasteners. Guessing an adjustment or relying on a sealed mechanism is unsafe. Storing a click wrench at its lowest setting is correct practice, but oiling internals is not.

Question 31Hand tools, measuring instruments and workshop equipment

Which workshop equipment is used to check that a motorcycle frame or fork tube is straight after a collision repair?

  1. Vernier caliper alone
  2. Hydraulic press without gauges
  3. Surface plate with dial indicator and V-blocks Correct answer.
  4. Bench grinder with wire wheel

Explanation

A surface plate provides a flat reference, and V-blocks with a dial indicator show run-out as the part is rotated, revealing bends. A grinder or ungauged press cannot measure straightness, and a caliper measures local diameter rather than the axis of a long tube. This combination is standard for checking shaft and tube straightness.

Question 32Hand tools, measuring instruments and workshop equipment

What is the correct way to store precision measuring instruments such as micrometers and vernier calipers at the end of a shift?

  1. Stored with the measuring faces pressed together and locked
  2. Left on the bench with jaws closed tightly to protect the faces
  3. Hung on a nail near the grinding area for quick access
  4. Clean, lightly oiled, and kept in their cases in a dry cabinet Correct answer.

Explanation

Precision instruments should be cleaned of swarf and moisture, lightly protected against corrosion, and kept in cases in a dry place. Leaving them on a bench or near grinding dust exposes the measuring faces to damage and rust. Locking the faces tightly together can trap moisture and cause corrosion pitting.

Question 33Hand tools, measuring instruments and workshop equipment

A torque specification in the workshop manual is given as 25 N·m. The workshop torque wrench is marked only in kgf·m. Which conversion should be used?

  1. Multiply 25 by 9.81 to get about 245 kgf·m
  2. Use 25 kgf·m directly because the units are equivalent
  3. Divide 25 by 0.7376 to get about 33.9 kgf·m
  4. Divide 25 by approximately 9.81 to get about 2.55 kgf·m Correct answer.

Explanation

One kilogram-force metre equals about 9.81 newton metres, so a newton metre value is converted by dividing by 9.81. This gives roughly 2.55 kgf·m for 25 N·m. Multiplying instead of dividing produces a value almost ten times too large, which would over-torque and damage the fastener.

Question 34Hand tools, measuring instruments and workshop equipment

Which hand tool is the correct choice for loosening a seized front axle nut without damaging the nut corners?

  1. A pair of locking pliers clamped on the nut flats
  2. A twelve-point socket chosen for a tight fit
  3. A six-point socket of the correct size with a breaker bar Correct answer.
  4. An open-ended spanner one size larger than the nut

Explanation

A six-point socket contacts the full flat of the nut and resists rounding, and a breaker bar supplies the leverage needed for a seized fastener. An oversized open spanner or locking pliers grips only part of the flats and will round the corners. A twelve-point socket is more likely to slip under high load.

Question 35Hand tools, measuring instruments and workshop equipment

What is the purpose of a valve spring compressor in motorcycle engine repair?

  1. To check valve stem run-out
  2. To seat the valve into its guide
  3. To compress the valve spring so the collets can be removed or fitted Correct answer.
  4. To measure valve spring free length

Explanation

The compressor squeezes the valve spring so the retainer can be pushed down and the split collets freed from the valve stem groove. It does not measure anything. Spring free length is checked with a caliper against the service limit, and stem run-out is checked with a dial indicator on V-blocks.

Question 36Hand tools, measuring instruments and workshop equipment

A technician uses a steel rule to check the free length of a valve spring and records 38 mm, while the service limit is 39.5 mm minimum. What does this indicate?

  1. The measurement is invalid because a rule cannot be used
  2. The spring is below the service limit and should be replaced Correct answer.
  3. The spring should be shimmed to increase its length
  4. The spring is within specification and can be reused

Explanation

A measured free length shorter than the stated minimum means the spring has lost tension and must be replaced. Springs do not regain length by shimming, and a steel rule is acceptable for a rough free-length check when the limit is given to a fraction of a millimetre. Reusing a sagged spring risks valve float and poor sealing.

Question 37Hand tools, measuring instruments and workshop equipment

Which piece of workshop equipment provides a flat, true reference surface for checking a warped cylinder head face with a straight edge and feeler gauge?

  1. Engine stand
  2. Bench grinder rest
  3. Surface plate Correct answer.
  4. Hydraulic press bed

Explanation

A surface plate is machined flat to a known tolerance and gives a true datum for straightness and flatness checks. The head is placed on it or checked with a straight edge and feeler gauge to reveal warping. A grinder rest, press bed, or engine stand is not made to a flatness standard suitable for measurement.

Question 38Hand tools, measuring instruments and workshop equipment

A piston is being measured with a micrometer to check skirt wear. Where should the measurement be taken according to normal practice?

  1. At the ring land diameter below the top ring
  2. At the crown centre in line with the pin
  3. Across the gudgeon pin bosses at the top of the piston
  4. At right angles to the gudgeon pin axis, at the specified height up the skirt Correct answer.

Explanation

Piston skirt wear is assessed across the thrust face, at right angles to the pin axis, at the height stated in the manual. Measuring across the pin bosses or at the crown does not reflect skirt clearance. Ring land diameter is a separate check and does not indicate skirt wear.

Question 39Hand tools, measuring instruments and workshop equipment

Why should an impact wrench not be used to tighten the small bolts on a motorcycle engine casing?

  1. It applies uncontrolled torque that can strip threads or crack the casting Correct answer.
  2. It cannot fit a socket of the right size
  3. It turns too slowly to seat the bolt
  4. It leaves the bolt threads oily

Explanation

An impact wrench delivers repeated high-energy blows with no torque control, which easily strips threads in aluminium or cracks thin castings. Small casing bolts require a low, specified torque applied with a calibrated wrench. Socket fit, speed, and oil residue are not the reason these tools are avoided here.

Question 40Hand tools, measuring instruments and workshop equipment

A technician needs to remove a bearing from a blind hole in an engine casing without damaging the bore. Which tool is appropriate?

  1. An oxy-acetylene torch to melt the bearing
  2. A blind bearing puller with an expanding collet Correct answer.
  3. A cold chisel used to split the outer race
  4. A hammer and a punch driven from the opposite side

Explanation

A blind bearing puller expands a collet inside the bearing bore and draws the bearing out without access to the far side. There is no opposite side to punch from in a blind hole, and a chisel or torch would damage the casing bore and bearing seat. Heating the whole casing is a separate technique and not the tool described here.

Question 41Motorcycle engine systems: principles, components and overhaul

On a four-stroke motorcycle engine, which stroke immediately follows the power stroke in the operating cycle?

  1. Intake stroke
  2. Exhaust stroke Correct answer.
  3. Compression stroke
  4. Scavenging stroke

Explanation

The four-stroke cycle runs intake, compression, power, then exhaust. The exhaust stroke pushes burnt gases out through the open exhaust valve as the piston rises. Scavenging is a two-stroke term and is not one of the four strokes.

Question 42Motorcycle engine systems: principles, components and overhaul

In a two-stroke engine, what is the main function of the reed valve or piston-port arrangement in the intake tract?

  1. To allow the fresh charge in while preventing it from being pushed back out Correct answer.
  2. To control oil flow to the gearbox bearings
  3. To regulate the flow of coolant through the cylinder jacket
  4. To open the exhaust port at the correct moment

Explanation

A two-stroke intake uses crankcase pressure pulses, so a one-way valve or piston-controlled port is needed. It admits mixture on the upstroke and closes to stop blow-back on the downstroke. This is essential for crankcase scavenging to work.

Question 43Motorcycle engine systems: principles, components and overhaul

A mechanic finds the piston ring end gap below the minimum specification on a new ring fitted to a worn but serviceable bore. What is the correct action?

  1. Fit the ring as supplied and rely on break-in to open the gap
  2. Increase bore clearance by honing the cylinder further
  3. Install two ring expanders behind the ring
  4. File the ring ends squarely until the gap is within specification Correct answer.

Explanation

Ring end gap must be set in the actual bore before assembly. If the gap is too small, the ends butt when the ring heats and the ring can break or scuff the bore. Filing the ends squarely to the specified gap is the standard remedy.

Question 44Motorcycle engine systems: principles, components and overhaul

Which component converts the reciprocating motion of the piston into rotating motion in a motorcycle engine?

  1. Clutch basket and primary drive
  2. Connecting rod and crankshaft assembly Correct answer.
  3. Oil pump and relief valve
  4. Camshaft and rocker arm assembly

Explanation

The connecting rod links the piston to the crankshaft journal. As the piston moves up and down, the rod swings and forces the crank to rotate. The camshaft, clutch and oil pump have different functions.

Question 45Motorcycle engine systems: principles, components and overhaul

During a compression test on a warm single-cylinder four-stroke engine, the gauge reads well below specification. Adding a few drops of oil to the cylinder raises the reading noticeably. What does this indicate?

  1. Leaking intake valve
  2. Blown head gasket
  3. Worn piston rings or bore Correct answer.
  4. Incorrect camshaft timing

Explanation

Oil temporarily seals the ring-to-bore gap, so a rise after oiling points to ring or bore wear. Valve leakage or a head gasket fault would not improve much with added oil. This is the classic wet-versus-dry compression comparison.

Question 46Motorcycle engine systems: principles, components and overhaul

What is the purpose of valve clearance (tappet clearance) on an engine with mechanical valve adjustment?

  1. To reduce oil pressure in the cylinder head
  2. To allow for thermal expansion so the valve still seats fully when hot Correct answer.
  3. To keep the valve spring compressed at rest
  4. To increase valve lift at high engine speed

Explanation

Metal expands as the engine warms, so a small gap is left in the valve train. Without it the valve may be held slightly open when hot, causing compression loss and burnt seats. Too much clearance causes noise and reduced lift.

Question 47Motorcycle engine systems: principles, components and overhaul

A motorcycle engine has correct valve clearance but the exhaust valve clearance closes up completely after a few hundred kilometres. What is the most likely cause?

  1. Worn camshaft bearing
  2. Stretched timing chain
  3. Weak valve spring
  4. Valve seat recession into the cylinder head Correct answer.

Explanation

If the valve seat wears or recesses, the valve sits deeper in the head and the clearance shrinks. This is common with unleaded fuel and soft seats. A stretched chain or worn bearing changes timing but does not usually close the clearance to zero.

Question 48Motorcycle engine systems: principles, components and overhaul

Which type of camshaft drive gives the most accurate valve timing over long service with minimal adjustment?

  1. Timing chain without tensioner
  2. Pushrod and gear train
  3. Toothed belt Correct answer.
  4. Chain with automatic tensioner

Explanation

A toothed belt does not stretch appreciably and needs no lubrication, so timing stays accurate with only periodic replacement. Chains wear and stretch and rely on a tensioner. Pushrod systems add flex and clearance.

Question 49Motorcycle engine systems: principles, components and overhaul

After overhaul, a technician sets the piston at top dead centre on the compression stroke and aligns the camshaft marks. Why is this alignment critical?

  1. It establishes the correct relationship between piston position and valve opening Correct answer.
  2. It adjusts the oil pump drive ratio
  3. It sets the ignition timing to the correct advance curve
  4. It determines the clutch release point

Explanation

Cam timing determines when valves open relative to piston position. If the cam is one tooth out, the engine may run poorly, lose compression or contact valves and pistons. Ignition and oil pump timing are separate adjustments.

Question 50Motorcycle engine systems: principles, components and overhaul

What is the main advantage of a multi-valve (four-valve) cylinder head over a two-valve design of similar displacement?

  1. Higher compression ratio without machining
  2. Lower manufacturing cost
  3. Simpler valve adjustment
  4. Better breathing at high engine speed due to greater valve area Correct answer.

Explanation

Four smaller valves give more total flow area and a central spark plug position. This improves volumetric efficiency at high speed and allows better combustion chamber shape. Cost and adjustment complexity usually increase, not decrease.