If your bike struggles to accelerate, feels sluggish, or doesn’t respond like it used to, it may need attention. Dirty air filters, old engine oil, worn spark plugs, or fuel system issues can all reduce engine performance. A healthy bike should run smoothly. If you hear knocking, grinding, squeaking, or rattling sounds, don’t ignore them. Modern bikes often include dashboard warning lights that should never be ignored. Similarly, oil stains under your parked bike may indicate an engine oil leak or another fluid issue.