Getting your engine to talk to you Part 1... noises

Getting your engine to talk to you Part 1

Today we will go over the common sounds your MX bike's engine can make when it is having an issue. Let's call it the language of a sick engine.

1. A clapping rattle sound at the base of the cylinder. Is most usually caused by a bad lower connecting rod bearing.
2. A tapping sound near the top of the cylinder. Is usually caused by the gap between the cam or follower and the top of the valve. There are a couple of causes of this and it will require a small amount of disassembly to confirm the cause.
3. A slapping sound on the side of the cylinder. Is often caused by a frozen cam chain tensioner or a broken cam chain guide.
4. A rumbling noise from the clutch. Pull the clutch lever in and release the sound should change. This isn't always a defect but it is worth doing a thorough inspection of the clutch assembly.
5. A ticking sound from the transmission is often caused by a broken tooth on a gear.
6. A whirring noise. Bearings  (not rod bearings) can make a "whurring" or squeeling noise but you will usually find bad bearings by feel.
7. A ping or rattle noise when you have the engine loaded hard. Is often caused by detonation often called pre-ignition. Increase the octane of your gas and re-test.
8. A squeal or whining noise from the water pump area is most likely a water pump bearing.
9. A grinding/chunking sound when you shift is often caused by a bent shift fork or worn gear engagement dogs or as simple as a shift lever that was bent in a crash and no longer has full travel.
10. Before you focus on your engine when you hear a new noise while riding be sure it isn't another part of the bike such as the chain, chain guide, brakes etc etc.

Stay greasy my friends.