How to Diagnose Rich and Lean Conditions
When tuning a bike for the first time, it may be difficult to figure out if your bike is running too rich or too lean. Both conditions can be very harmful to your bike and cause serious damage as well as create an unsafe riding condition. The following list will help you determine whether your Bike is running rich or lean.
Lean Mixture Symptoms -
1 - It is difficult to apply the throttle quickly or the engine picks up speed when the throttle is rolled off.
2 - The engine knocks or Pings or overheats.
3 - The engine surges or hunts for a stable RPM while cruising at part throttle.
4 - Engine acceleration is flat or slow to pick up.
5 - When the pilot circuit is too lean, there will be popping or spitting in the carburetor as the throttle is opened. Sometimes there will be popping or after fire in the exhaust on deceleration after the throttle has been closed.
6 - Engine performance improves in warmer weather, or runs poorly in cold weather.
7- Engine performance worsens when intake is removed.
8 - Baked white and flaky spark plugs.
Rich Mixture Symptoms -
1 - Engine acceleration is flat, uneven, not crisp.
2 - The throttle needs to be opened continuously to maintain consistent acceleration.
3 - The engine performs poorly when the weather gets warmer, or the engine works better in cold conditions.
4 - Black smoke coming out of the exhaust.
5 - Poor fuel economy.
6 - Engine performance improves when the intake is removed.
7 - When the pilot circuit is rich, the engine will idle roughly, or not return to idle without blipping the throttle, the exhaust can smell of excessive fuel and burn the eyes.
8 - Black sooty or fouled spark plugs, black and sooty exhaust tail pipes.