Why Can't the Motorcycle Exceed 60?

[LeoMarie]

Motorcycle unable to exceed 60 may be caused by the following reasons: 1. Lean fuel mixture: A lean air-fuel mixture results in insufficient thrust on the piston after ignition, prolonged combustion time, and engine overheating. Symptoms of a lean condition include poor acceleration during operation, which improves when manually adjusting the choke or pumping fuel, but returns to poor acceleration when not enriching the mixture. 2. Rich fuel mixture: An overly rich mixture causes poor acceleration at low speeds. The lack of sufficient oxygen during combustion leads to incomplete burning, reduced power, worsened fuel economy, and excessive carbon buildup that can clog the exhaust system. 3. Clogged air filter or high carburetor float level: Issues such as carburetor float chamber overflow, loose main jet, poor enrichment system reset, or clogged main air jet. 4. Poor fuel quality or incorrect gasoline octane rating: Can cause knocking; stale gasoline decomposes and loses calorific value; water in fuel leads to intermittent engine operation and backfiring; presence of other contaminants in gasoline.