Why is the cylinder head screw of a underbone motorcycle leaking engine oil?

[Mila]

The cylinder head screw of a underbone motorcycle leaks engine oil because there is too much oil. Detailed reasons and solutions for the cylinder head screw of a underbone motorcycle leaking engine oil are as follows: The cylinder head screw of a underbone motorcycle is used to check the oil condition in the oil passage. Since it is located in the oil passage, excessive oil can easily cause leakage. Solution: You can remove the screw when the engine is off, clean the copper washer and the screw hole thoroughly, and carefully check whether the contact surface between the copper washer and the cylinder head cover is uneven. If there is no problem, just reinstall the screw properly. You can also apply a small amount of high-quality sealant on both sides of the copper washer and the threads. When tightening the screw, do not make it too tight; just tighten it properly to avoid damaging the screw and the screw hole.

[DiAshlyn]

I know all about oil leaks from cylinder head screws on underbone motorcycles. My old underbone started seeping oil after three years of riding - mainly due to screw expansion under engine heat and aging/deformed gaskets. Those gaskets originally serve as cushions, but prolonged exposure to engine oil makes them brittle and crack. Before a long trip once, I noticed significant oil level drop on the dipstick and spotted oil stains around the screws. Luckily I addressed it promptly. After tightening the screws and replacing gaskets at the shop for just 80 yuan, the issue disappeared completely. I recommend developing a habit of checking screw tightness before starting, especially before highway rides. A major leak could leave oil trails and insufficient lubrication may damage engine internals. This simple, cost-effective routine ensures safer riding.

[DiGeorge]

As a underbone motorcycle owner for over a decade, I've encountered cylinder head screw oil leaks several times. The core reasons boil down to just a few: screws not tightened properly during installation or over-tightened damaging threads; poor-quality sealing rings aging and disintegrating; engine heat and pressure accelerating wear causing gaps. The last oil leak on my bike happened because the mechanic took shortcuts and didn't replace the gasket during previous maintenance. The solution is actually simple: for minor seepage, first tighten screws to standard torque using a wrench without excessive force; for serious leaks, replace the O-ring (costs around 10 yuan). Never ignore this seemingly small issue - losing too much engine oil can cause overheating and cylinder seizure, potentially leading to thousands in overhaul costs. During routine maintenance, always check oil levels and engine cleanliness.

[AriannaDella]

Oil Leak from Cylinder Head Screws on Underbone Motorcycle

I recently experienced this issue. A friend who is a motorcycle mechanic told me that during engine operation, high temperatures and strong vibrations cause the screws to deform under prolonged pressure, leading to seal gasket failure and oil leakage. My bike was fine when new, but after two years of riding, oil droplets appeared near the screws, possibly due to assembly deviation or material fatigue. I tried wiping the area clean with a towel to observe the leak location but didn't dare to tamper with the screws for fear of causing damage. Later, a professional inspection revealed that the gasket had aged and lost elasticity. Replacing it immediately stopped the leak. A reminder to beginners: don't attempt DIY fixes—leave it to experienced professionals for the quickest solution. Oil leaks pose significant risks; engine oil deficiency can burn internal components and affect riding safety.