Motorbike or scooter · Problems

Motorbike misfiring

Flat spots, backfiring or an engine running on one cylinder fewer point to ignition or fuelling.

UrgencyLow
Can I drive?Yes, carefully
Likely causesWorn spark plugs

Likely causes

  1. Worn spark plugs35%
    Garage price: Motorbike spark plugs £40 – £225
  2. Dirty carburettor30%

    After winter storage with fuel in the bowl, the jets clog: unstable idle, flat spots when opening the throttle.

    Garage price: Carburettor clean £70 – £305
  3. Unsynchronised carbs or throttle bodies20%
    Garage price: Carburettor or throttle body sync £45 – £120
  4. Valve clearance out of spec15%
    Garage price: Valve clearance check £145 – £715

What you can check yourself

  1. A dry black plug means too rich a mixture, a white one too lean.

Fault codes often linked

P0300 Random or multiple cylinder misfireP0301 Cylinder 1 misfire detectedP0302 Cylinder 2 misfire detectedP0303 Cylinder 3 misfire detectedP0304 Cylinder 4 misfire detected

Frequently asked questions

Motorbike misfiring: what causes it?

Likely causes: worn spark plugs (35%), dirty carburettor (30%), unsynchronised carbs or throttle bodies (20%).

Can I drive?

Yes, carefully. Urgency: low.

Indicative estimate. MecaScan cannot see your vehicle: always have a diagnosis confirmed by a professional, and never work on brakes, steering or airbags without the skills.