State: STOP AND CHECK
Bike will not start: one click from the starter area
What it may involve
A weak battery is common, but one click can also involve battery terminals, the earth connection, starter relay/solenoid, wiring or starter motor.
Safe observations
- Do the dashboard and lights dim heavily when the starter is pressed?
- Are the battery terminals visibly loose or corroded?
- Is the engine-stop switch in the run position?
- Is the bike in neutral, or are the clutch and side-stand interlocks satisfied?
- Does the handbook describe a key or immobiliser warning?
What not to do
Do not repeatedly hold the starter button, bridge terminals, bypass safety switches or jump-start the motorcycle without following the manufacturer's procedure.
Related explainers
BatteryStarter motorStarter relay/solenoidImmobiliserSide-stand switch
State: STOP AND CHECK
Engine warning with reduced power
What it may involve
The ECU may have placed the motorcycle into a reduced-power mode after detecting an engine, fuelling, throttle, ignition, emissions, sensor or electrical fault.
Safe observations
- Is the warning steady or flashing?
- Is another red warning present?
- Is the engine running roughly, smoking, leaking or unusually hot?
- Does the handbook allow continued riding?
What not to do
Do not assume a scan code identifies the part that must be replaced. A code describes what the system detected and still requires diagnosis.
Action
If the warning flashes, the engine runs poorly, fuel leaks, smoke appears or another serious warning is present, stop safely. If the handbook permits continued use and the bike runs normally, ride gently only as far as necessary for diagnosis.
Related explainers
Engine-management/FI warningECUThrottle bodyFuel injectorsSensors
State: INVESTIGATE SOON
Clunk from the rear when taking up drive
What it may involve
Possible sources include excessive chain slack, worn chain or sprockets, cush-drive rubbers, loose or worn driveline parts, transmission backlash, belt-drive components or shaft-drive joints and gears.
Safe observations
- Is the chain visibly very loose, damaged or uneven?
- Does the clunk occur only during abrupt throttle or clutch use?
- Is there excess play at the rear wheel or final drive?
- Did the symptom start after wheel, tyre or chain work?
What not to do
Do not tighten the chain without measuring it by the handbook method. Do not assume every shaft-drive clunk is a bevel-gear failure.
Related explainers
Chain and sprocketsCush driveClutchBelt final driveShaft final drive
State: DO NOT RIDE
Spongy or soft brake lever or pedal
What it may involve
Air, fluid loss, degraded fluid, hose expansion, caliper trouble, master-cylinder trouble or another hydraulic fault can change brake feel.
Safe observations
Look for obvious leakage without dismantling anything. Check whether the fluid is below its marked range and whether the lever or pedal travel has changed.
What not to do
Do not keep pumping the control and treat temporary firmness as a repair. Do not simply top up low brake fluid without finding the cause.
Action
Arrange inspection or recovery before riding.
Related explainers
Brake fluidBrake linesMaster cylinderBrake calipers
State: STOP AND CHECK
Oil visible on a front fork
What it may involve
A fork seal may be leaking, but residue can also come from trapped dirt, previous maintenance or another source.
Safe observations
- Is the fork tube wet after being cleaned and compressed again?
- Has oil reached the brake disc, caliper, pads or tyre?
- Is suspension action or damping different?
What not to do
Do not ride if oil has reached a brake or tyre. Do not use a makeshift seal-cleaning tool unless you understand the risk of damaging the seal or fork tube.
Related explainers
Fork sealsFront forksBrake discsBrake pads
State: INVESTIGATE RIDING INPUT AND MECHANICAL CONDITION
Rear wheel hops during a hard or rapid downshift
What it may involve
Rear-wheel hop can result from an abrupt downshift, excessive engine braking, poor rev matching, clutch release technique, a low-grip surface or a motorcycle without a slipper clutch. A slipper clutch is designed to reduce hop; hop alone does not prove that it or the clutch plates have failed.
Safe observations
- Did the downshift select a gear too low for the road speed?
- Does it happen only with rapid clutch release?
- Does the clutch slip during acceleration or behave abnormally at other times?
- Does the bike have a slipper or assist clutch?
What not to do
Do not reproduce violent downshifts on the road to test the symptom.
Action
Use smooth, appropriate downshifts. Seek rider training if technique is uncertain and mechanical inspection if the clutch slips, drags, makes new noises or behaves inconsistently.
Related explainers
ClutchSlipper and assist clutchGearbox
State: INVESTIGATE SOON
Battery repeatedly goes flat
What it may involve
An ageing battery, charging-system fault, loose connection, parasitic drain, accessory wiring, alarm, cold weather or repeated short journeys can all leave a battery discharged.
Safe observations
- How old is the battery?
- Does a charging warning appear?
- Has an accessory or alarm recently been fitted?
- Does the bike sit unused or make only short journeys?
- Are the terminals visibly secure and clean?
What not to do
Do not assume the battery or charging system is at fault without testing both. Do not replace the battery repeatedly while ignoring a drain or charging problem.
Related explainers
BatteryAlternator/statorRegulator/rectifierCharging warning
State: STOP RIDING WHEN SAFE
Engine-temperature warning
What it may involve
Low coolant, a leak, radiator-fan or thermostat fault, water-pump problem, restricted radiator airflow or another cooling-system issue may be involved.
Safe observations
Stop safely and switch off the engine. Allow it to cool. Never remove a pressurised coolant cap while hot.
What not to do
Do not leave an overheating engine idling as generic advice. Do not continue merely because the warning temporarily disappears.
Related explainers
Coolant-temperature warningRadiatorThermostatWater pump
