What are the reasons for a motorcycle not accelerating and lacking power?

[Galadriel]

The main reasons for a motorcycle not accelerating include carburetor blockage, improper air-fuel mixture, excessively small valve clearance, and fuel shortage. Carburetor blockage: If the idle jet is clogged, it manifests as no idle speed; if the main jet is clogged, it results in poor acceleration at high speeds, commonly referred to as "not accelerating." This issue can typically be resolved by removing and cleaning the carburetor. Improper air-fuel mixture: When the air-fuel mixture is incorrect, the motorcycle may exhibit unstable idle speed and a sensation of not accelerating. This is relatively easy to fix by adjusting the idle speed screw until the idle stabilizes. Excessively small valve clearance: For most standard motorcycles, valve clearance ranges between 0.05-0.12mm, varying by manufacturer and model. To check valve clearance, you can remove the valve cover or cylinder head cover, align the timing, and inspect the valve clearance. Alternatively, if you feel the rocker arm is very tight with no play when moved by hand, the clearance is too small. Fuel shortage: Check if the fuel tank is low on fuel.

[MilaLynn]

Motorcycles losing power when accelerating is a very common issue. It's most likely caused by a clogged carburetor - restricted fuel flow is like a person struggling to breathe. I suggest you check the air filter; if the foam is blackened, replace it immediately. The spark plug might also have severe carbon buildup, so remove it and clean the electrode gap. A blocked exhaust pipe can also make the engine feel suffocated - listen if the exhaust sounds muffled when revving. Also, the fuel tank petcock filter often gets clogged; after turning off the engine, disconnect the fuel line to check if fuel flows freely. You can try inspecting these yourself first, and only seek professional help if the problem persists.

[EleanorMarie]

I've encountered this situation many times, and the reasons mainly focus on a few areas: fuel, air, and electricity. If the gasoline is of poor quality or has been stored for too long and deteriorated, the engine will have a 'bad stomach.' A clogged air filter will 'suffocate'—take it out, tap it clean, or replace it directly. An imbalanced carburetor mixture or worn needle can cause insufficient fuel supply. In terms of ignition, aging high-voltage coils or poor contact in the spark plug cap can weaken the spark. Clutch slippage can also prevent power from being transmitted, especially in older vehicles. If the engine oil hasn't been changed for too long and becomes too viscous, the engine will also feel 'sticky and sluggish,' losing its power.

[SanCaden]

Throttle feels sluggish when fully twisted? First confirm the gasoline is fresh, then check these three areas: 1) See if the fuel line from the tank to the carburetor is kinked, 2) Check if the air filter box has a mouse nest clogged with debris, 3) Verify if the carburetor breather tube is clogged with mud. Also test if the battery voltage is insufficient, as it affects ignition efficiency. If you've installed a high-flow exhaust pipe without carburetor adjustment, low RPM performance will be particularly weak. Finally, check if the clutch engagement is too short - observe wheel rotation resistance when pulling the clutch. These checks should basically pinpoint the issue.