also surging could be caused by running too lean or too rich.
*************************************************
Typical Lean Conditions:
- Poor acceleration; the engine feels flat.
- The engine won't respond when the throttle is snapped open, but it picks up speed as the throttle is closed. (A too-large main jet also mimics this symptom.)
- The engine runs hot, knocks, pings and overheats.
- The engine surges or hunts when cruising at part-throttle.
- Popping or spitting through the carb occurs when the throttle is opened. Or popping and spitting occurs through the pipe on deceleration with a closed throttle.
- The engine runs better in warm weather, worse in cool.
- Performance gets worse when the air filter is removed.
Typical Rich Conditions
- Engine acceleration is flat and uneven and loses that "crisp" feel.
- The engine "eight-strokes" as it loads up and skips combustion cycles.
- The engine's idle is rough or lumpy, and the engine won't return to idle without "blipping" the throttle.
- The throttle needs to be open continuously to maintain acceleration.
- Black, sooty plugs, a sooty exhaust pipe and black smoke from the tailpipe that stinks of unburned fuel.
- Poor fuel economy.
- The engine works better when cold. Performance falls off as it warms up or the ambient temperature rises.
- Engine performance improves when the air cleaner is removed.