What does an overbored engine mean?

2 Answers
ODavid
07/28/25 11:00pm
Overboring refers to the process of using a machine to finely grind the inner walls of the cylinder, allowing for an increase in size that varies depending on the vehicle. The cylinder can be enlarged as much as possible without grinding through it, and then pistons of corresponding sizes are installed. This is the ultimate method to increase horsepower, but it is not commonly used under normal circumstances. After grinding, the inner walls of the cylinder become locally thinner, leading to uneven pressure distribution within the cylinder, which makes it highly prone to cylinder explosion (also known as cylinder scoring). Below is an introduction to cylinder scoring repair: Cylinder replacement: If the cylinder scoring is severe and the remaining material on the cylinder walls exceeds the allowable machining tolerance, making it impossible to select suitable pistons and rings, the usual solution is to replace the cylinder, pistons, and rings as a complete set. Cause: In motorcycles, cylinder scoring occurs when the cylinder lacks lubrication and comes into abnormal close contact with the piston, resulting in a rough surface. When this phenomenon occurs in a motorcycle, not only does the power decrease, but it also leads to severe oil burning issues.
Was this review help?
12
4
Share
DiArianna
08/12/25 3:26am
A bored-out engine is essentially about enlarging the original engine cylinders. You see, many people feel their cars aren't powerful enough and want more punch, so they increase the cylinder diameter. This boosts displacement, allowing more fuel to be injected and generating greater power through combustion. But this requires caution – overdoing modifications can make the engine prone to failure. I once modified a small sports car myself; after boring out the cylinders, it was indeed faster, but soon fuel consumption shot up and it needed multiple repairs. It's best to find a reliable tuning shop and not cut corners. Boring out isn't a cure-all – sometimes adding a turbocharger is a safer and more efficient solution.
Was this review help?
15
3
Share
Expand All
More Forum Discussions

What Are the Motorcycle Riding Techniques?

Within a well-lit and clear line of sight, ensure the road surface is flat and firm, gradually reduce your speed, and remember not to stop or brake abruptly. Make sure your legs have enough strength to support the motorcycle. Based on the principles of noise reduction, motorcycle mufflers can be divided into the following three types: 1. Resistive Muffler: This type of muffler uses sound-absorbing materials or structures to attenuate noise as it travels along the pipe, achieving noise reduction. Common sound-absorbing materials include glass fiber strands, low-carbon steel wire mesh, and felt. These mufflers are effective for high-frequency noise but perform poorly for low-frequency noise. 2. Reactive Muffler: This type of muffler relies on sudden expansion (or contraction) of the pipe cross-section or the addition of a resonance chamber to reflect certain frequencies of sound waves back toward the source, thereby reducing noise. 3. Impedance Composite Muffler: This type combines the principles of resistive and reactive mufflers through an appropriate structural design, incorporating the noise reduction characteristics of both.
19
1
Share

How Many Years After License Revocation Can You Retake the Test?

If the license is revoked due to a hit-and-run accident constituting a crime, the driver is permanently banned from obtaining a license. Below is relevant information on applying for a motor vehicle driver's license: Age Requirements: To apply for a license for small cars, small automatic transmission cars, small automatic transmission passenger cars for the disabled, or light motorcycles, the applicant must be between 18 and 70 years old. To apply for a license for low-speed trucks, three-wheeled cars, ordinary three-wheeled motorcycles, ordinary two-wheeled motorcycles, or wheeled self-propelled machinery, the applicant must be between 18 and 60 years old. Physical Requirements: To apply for a license for large buses, tractors, city buses, large trucks, or trolleybuses, the applicant must be at least 155 cm tall. To apply for a license for medium-sized buses, the applicant must be at least 150 cm tall. Vision: For large buses, tractors, city buses, medium-sized buses, large trucks, trolleybuses, or trams, the applicant's naked or corrected vision must reach at least 5.0 on the logarithmic visual acuity chart.
12
1
Share

How Many Questions Are There in the Driving Test Subject 4?

According to the "Regulations on the Application and Use of Motor Vehicle Driving Licenses," Subject 4 consists of a total of 50 questions, each worth 2 points, totaling 100 points. Questions 1-10 are true/false questions; questions 11-40 are single-choice questions; and questions 41-50 are multiple-choice questions. The test includes various question types such as image analysis, animated case studies, and text descriptions. The scope of Subject 4 covers driving knowledge under adverse weather and complex road conditions; identification of common traffic signs, markings, and hand signals; traffic accident rescue and hazardous material handling knowledge; comprehensive judgment of violations and case analysis; emergency avoidance knowledge; safe driving knowledge; and driving ethics and civilized driving knowledge. According to the "Regulations on the Application and Use of Motor Vehicle Driving Licenses," there is no limit to the number of attempts for Subject 1 and Subject 4. If you fail the first attempt on the same day, you can retake the test immediately. If you still fail, you need to reschedule the test, and no additional fees are required for retakes. However, it is important to note that the validity period of the driving skills test permit is three years. If the applicant does not complete the test within the validity period, the results of any passed subjects will be invalidated. Subject 4, also known as the Subject 4 theory test or driver theory test, is part of the motor vehicle driving license assessment. After the implementation of the Ministry of Public Security's Order No. 123, Subject 3 was divided into two parts: the road test and an additional safety and civilization knowledge test, commonly referred to as "Subject 4," which assesses "driving ethics." Subject 4 is the colloquial name for the safety and civilization driving knowledge test under Subject 3 and is not a separate subject. Because this test is conducted after Subject 3, it is commonly referred to as the Subject 4 test. Officially, there is no Subject 4. The safety and civilization driving knowledge test is conducted after Subject 3. Subject 4 Test Notes: Test Duration: The test lasts 45 minutes. If you make mistakes totaling 10 points (5 questions) during the test, the session will be terminated. Number of Questions: Depending on the type of driving license being tested, 50 questions are randomly selected from the corresponding Subject 4 question bank, with each question worth 2 points. Question Types: The test includes single-choice questions (including true/false questions) and multiple-choice questions, with question formats such as animated questions, image-based questions, situational recognition questions, and text-based questions. Retake Notes: If you fail Subject 4, you only need to retake Subject 4. The driving school will schedule the retake, and there is no limit to the number of retakes. No additional fees are required for retakes. The driving test consists of three subjects: Subject 1, Subject 2, and Subject 3, with Subject 3 divided into two parts. Subject 1 refers to the examination on road traffic safety laws, regulations, and related knowledge; Subject 2 refers to the field driving skills test; and Subject 3 refers to the road driving skills and safety and civilization driving knowledge test.
3
2
Share

What are the reasons for the engine icon on the dashboard to light up?

The reasons for the engine icon on the dashboard to light up include sensor issues, maintenance problems, and fuel quality issues. Sensor Issues: The sensors mentioned here include those for coolant temperature, crankshaft position, air flow, intake air temperature, oxygen sensors, etc. When these sensors are damaged, have poor contact, or experience signal interruption, the car's ECU cannot accurately obtain engine data, which will then trigger the engine fault light. Maintenance Problems: Poor engine maintenance is the most common cause of the engine fault light turning on. Vehicles have specific maintenance cycles, and if the driver does not adhere to these cycles, combined with poor driving habits, it will increase the burden on the engine's operation, eventually leading to the fault light as a warning. Fuel Quality Issues: The fuel quality referred to here includes both fuel and engine oil. The fuel added to a car usually has a specific grade, and engine oil can be either semi-synthetic or fully synthetic. Manufacturers generally recommend which grade of fuel and which type of engine oil the driver should use. If the driver does not follow these recommendations, it can lead to engine wear over time.
19
0
Share

What Causes the Whistling Sound in the Engine?

Possible causes include engine bearing or intake system failure. It is recommended that the owner contact the local 4S store for inspection and repair to avoid potential damage. Below is relevant information about the engine: The function of the engine: The car engine is the device that provides power to the vehicle, acting as the heart of the car, determining its power, fuel efficiency, stability, and environmental performance. Materials used: Engine oil is a crucial material for the engine. It contains various additives that effectively protect the engine's vital moving components, ensuring normal operation.
7
1
Share

How to Drive a Semi-Automatic Transmission Vehicle?

Manual transmission requires gear shifting through the clutch, while automatic transmission eliminates the need for a clutch and relies on computer-controlled shifting. Semi-automatic transmission is also computer-controlled, but when switched to manual mode, it simply involves pushing up to shift up and pushing down to shift down without using the clutch. Essentially, it converts the computer-controlled gear shifting of an automatic transmission to manual operation while retaining the underlying automatic transmission principles. The semi-automatic transmission is designed to enhance the fuel efficiency and handling of automatic transmissions, returning the control of shift timing from the computer back to the driver. Fuel-saving techniques for semi-automatic vehicles include: Pay attention to daily vehicle maintenance. Proper vehicle upkeep is crucial; accelerated aging can increase fuel consumption. Minimize unnecessary energy consumption. During acceleration, using the D (Drive) mode throughout is the most fuel-efficient. During deceleration, manually downshifting to maintain engine speed around 2000 RPM is optimal for fuel efficiency, especially when going downhill. Using manual mode to control speed saves much more energy than relying on brakes. Keeping the engine speed below 2500 RPM and maintaining a steady speed is more fuel-efficient. For private vehicles, a speed range of 70-90 km/h is generally the most economical.
10
4
Share
Cookie
Cookie Settings
© 2025 Servanan International Pte. Ltd.