What lubrication method is typically employed for small motorcycles and scooters________________?
Show answer Hide answer
Answer: E. mixing about 5% lub oil with petrol
Explanation
Small two-stroke engines lack a dedicated pressurized oil sump lubrication system. Lubricating oil is mixed directly with petrol at a ratio of about five percent. This oil-fuel mixture lubricates internal bearings and cylinder walls during combustion. Two-stroke engines use the crankcase to compress the incoming air-fuel charge. Standard wet sump oiling is impossible because the crankcase handles fuel mixture flow. Two-stroke oil must burn cleanly with minimal carbon deposit buildup on components.
Older scooters, mopeds, and small garden equipment relied heavily on petroil lubrication. Modern two-stroke engines often use separate oil injection pumps for better control. Mixing oil and petrol incorrectly can lead to engine seizure or excessive smoke emissions. Forced lubrication systems require pumps and passages found in four-stroke engines. Splash lubrication is common in four-stroke crankcases rather than small two-stroke mixes. Grease under pressure cannot lubricate fast-moving internal combustion components effectively.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. How does the saturation temperature of steam change as pressure increases____________________?
Show answer Hide answer
Answer: B. rapidly first and then slowly
The saturation temperature of steam increases rapidly with pressure at lower ranges and more slowly at very high pressures. Thermodynamic property tables show that the Clapeyron vapor-pressure curve is non-linear across...
Q2. How does the thermal efficiency of a two-stroke cycle engine compare to a four-stroke engine_________________?
Show answer Hide answer
Answer: B. less
Two-stroke engines lose a portion of fresh air-fuel charge directly into the exhaust pipe. Incomplete scavenging leaves residual burnt exhaust gases inside the combustion cylinder volume. These scavenging inefficiencies...
Q3. For a semi-diesel cycle with fixed compression ratio and heat input, how does thermal efficiency respond to a higher pressure ratio_______________?
Show answer Hide answer
Answer: A. increase
The semi-diesel cycle combines elements of both constant volume Otto and constant pressure Diesel thermodynamic cycles. Holding the compression ratio and total heat input constant, increasing the pressure ratio raises pe...
Q4. How does the oscillation period of a floating body change when its metacentric height is increased_________________?
Show answer Hide answer
Answer: C. lower
The oscillation period of a floating body is inversely proportional to the square root of its metacentric height. A higher metacentric height increases restoring righting moments, causing the body to snap back faster fro...
Q5. Under what conditions is the tensile strength of wrought iron at its maximum _________________?
Show answer Hide answer
Answer: A. along the lines of slag distribution
Wrought iron manufacturing processes leave elongated fibrous slag inclusions embedded in the metal matrix. Tensile loads applied along the fiber direction engage the maximum strength of the iron. Cross-grain loading expl...
Q6. The total pressure on the surface of a vertical sluice gate 2 m x 1 m with its top 2 m surface being 0.5 m below the water level will be ________________?
Show answer Hide answer
Answer: D. 2000 kg
Total hydrostatic pressure on a submerged vertical gate is calculated by multiplying water specific weight, gate area, and centroid depth. The vertical sluice gate has dimensions of two meters by one meter, yielding a to...