Elective Units: Fuel, Ignition, Brakes, Suspension and Driveline
What the elective units cover
Elective units go deeper into systems: fuel and induction, ignition and electrical, braking, suspension and steering, and driveline and final drive. Questions tend to be diagnostic: given a symptom, identify the likely cause and the correct test.
Concepts you must know
For fuel systems, understand carburettor circuits (pilot, needle, main, choke) and electronic fuel injection inputs such as throttle position, manifold pressure, and oxygen sensors. For ignition, know coil, plug gap, and the difference between CDI and inductive systems. Braking covers hydraulic principles, pad and disc wear limits, fluid hygroscopy, and bleeding sequence. Suspension covers sag, damping, spring preload, and fork oil level. Driveline covers chain slack and lubrication, belt tension, and shaft drive oil.
Traps in questions
- Assuming rich running is always a jetting fault; a dirty air filter or restricted exhaust can cause it.
- Forgetting that brake fluid absorbs moisture and has a service interval regardless of mileage.
- Confusing preload with damping adjustment.
- Setting chain slack with the bike on a stand rather than at the specified load condition.
- Treating a weak spark as a plug fault when coil or earth may be the cause.
Worked rule of thumb
Diagnose before adjusting. For a misfire, test in order: spark quality, plug condition and gap, fuel delivery, then compression. A plug that is black and sooty points to a rich mixture or weak spark; a white, blistered plug points to lean running or overheating. Change one variable at a time and re-test.
Study approach
Build symptom-to-cause tables for each system, and practise measuring chain slack, pad thickness, and fork oil level to the manual specification.