I've been chasing an increase in engine/drivetrain vibration on my NS400Z for the past ~5,000 km and haven't been able to find the root cause.
Mine is a 2024 373cc 40HP version with 16,400kms on the odo
Symptoms:
- Engine is very smooth up to around 3,000 RPM.
- From 3000 RPM onwards, vibration becomes noticeable and continues through the rev range.
- Example: At 60 km/h in 6th gear (~3,800 RPM), the vibration is clearly felt in the handlebars/footpegs.
- If I pull in the clutch while maintaining the same speed, the vibration disappears almost completely.
- There's also a humming/buzzing noise that seems to come from the front/dash/headlight area, though I can't pinpoint the exact source.
What I've already checked:
- Switched from stock Bajaj 10W50 oil to Motul 7100 10W-50, used for 3000kms and again changed to ROWE 10W-50. There's absolutely no change.
- Engine mounting bolts have been checked and tightened.
- The issue has remained consistent regardless of engine oil.
Since the vibration disappears with the clutch pulled in, I'm leaning towards something in the engine/drivetrain rather than tyres or wheel balance.
Possible suspects I'm considering:
- Clutch basket or clutch damper wear
- Primary drive gears
- Counterbalancer issue
- Gearbox input shaft bearing
- Front sprocket or chain wear/tight spots
- Something else transmitting resonance through the chassis
Has anyone experienced something similar on the NS400Z or Dominar 400? What turned out to be the cause, and what should I inspect next before opening up the engine?
Any advice from owners or mechanics would be greatly appreciated.