Is it normal for the flathead screw on the left side of a motorcycle engine to rust?
1 Answers
It is normal for the flathead screw on the left side of a motorcycle engine to rust. This screw is only used during maintenance to check and confirm the valve timing. Removing it allows you to see the marks on the magneto rotor, but it serves no other purpose. Turning this screw will not cause abnormal engine noise; at most, it may lead to oil leakage due to poor sealing. If the flathead screw is on the cylinder block, it is a pushrod engine, and that screw is the lower rocker arm shaft. If the flathead screw is near the magneto, it is a chain-driven engine, and that screw is the valve timing inspection port. The screw has a sealing O-ring, and if it fails, it can cause oil seepage.