Did you know your motorcycle has a gatekeeper over its power? As riders, it’s easy to assume we’re the gatekeepers, but that isn’t necessarily true. Sure, we turn the throttle, but the engine has a gatekeeper of its own: the valves that control the air-fuel mixture the engine relies on to combust. The valves play an essential role in your motorcycle’s performance and, as a result, should be part of your motorcycle service interval routine.
What Do Engine Valves Do? Why Are They Important?
Unless you ride an electric motorcycle, your bike relies on an internal combustion engine to get you from point A to point B. The combustion process is a series of miniature explosions that depend on a mixture of air and fuel. The intake valves open to let the mixture flow into the engine, then close. This enables compression and ignition to turn the crankshaft and power your bike. Then, the exhaust valves open to let the leftover gases from the combustion process flow out of the engine. These valves close, the intake valves open, and the process starts all over again.
Valves have three pivotal roles in your bike’s performance. First, the intake valve serves as the engine’s gatekeeper and opens to let the fuel-air mixture into the combustion chamber. This opening is perfectly choreographed to optimize the flow of air and fuel to the chamber where it is ignited. Second, the gases produced from the combustion process must go somewhere, which is where the exhaust valve plays an essential role by opening to release the gases.
Think about this process occurring every time you turn the throttle. The chain reaction opens the valves, sends the air-fuel mixture into the chamber, initiates combustion, and the gases exit. But what happens when you downshift and let off the throttle to slow down? This is where the intake valve plays its final critical role: engine braking.
The valves work continuously, but letting off the throttle mitigates the amount of air that enters the cylinders. By regulating the airflow, a vacuum effect occurs, forcing the piston to work against this resistance. This resistance reduces the bike’s speed, reducing the wear on the bike’s brakes in exchange for what’s already occurring with the engine when you let off the throttle or downshift.
Why Valve Service Is Essential
Getting the most from your motorcycle’s performance starts by recognizing critical motorcycle service intervals, like the importance of routine valve service, as outlined by the manufacturer. Valves play a prominent role in your experience in the saddle, but what type of service do they require? What’s involved with a valve adjustment?
Your bike’s engine relies on a perfectly timed choreography between the valves and other components to initiate and complete the combustion process. The movement of these parts and the combustion process generate excessive heat, which causes the metal components to expand or swell. Engines are designed to account for this expansion, but everyday wear and tear can cause components like the valves to change positions and not fully seal properly.
When your bike rolls off the production line, the valves are positioned to create the perfect seal, with the proper lift and clearance to draw the mixture of air and fuel into the combustion chamber and later emit the spent gases via the exhaust. The position is critical because the valves must open and close at precise intervals for the engine to perform optimally.
When the engine is cold, the valve will have some free play, otherwise known as clearance or lash. This clearance accounts for the thermal expansion as the components heat. However, if the clearance or lash isn’t sufficient, the valve isn’t perfectly timed, nor can it create the ideal seal, which can cause performance issues and even extensive engine damage. Because of this, routine valve adjustments are essential to ensure the valve has the ideal clearance or lash.
Signs It’s Time for a Valve Adjustment
The recommended valve service interval differs for most motorcycle manufacturers, making it essential to check the manufacturer’s recommendation for your bike. However, this interval is a general guideline. You may notice your bike showing signs that the valves need to be adjusted sooner rather than later. Here are some of the most common valve-related signs of trouble.Decreased Power and Hard Starts
As a rider, your bike is an extension of yourself, so you’re perfectly attuned to its handling and performance. Because of this, you can easily recognize when the engine is struggling or isn’t reaching its optimal output. This decrease in power is a telltale indicator that the valves need to be adjusted. Beyond the engine not producing as much power as it should, you may also notice it has trouble starting. This is known as a hard start and is often caused by an improperly positioned valve. When the valve doesn’t have the right amount of clearance, the seal isn’t tight enough to contain the mixture of air and fuel in the chamber. Because of this, ignition is difficult, and the engine has trouble turning over.Overheating
Since the intake valve serves as a gatekeeper, its position plays a critical role in the engine’s operating temperature. The combustion process naturally generates a lot of heat, but this heat can be excessive if the valves don’t function correctly. A slight misadjustment where the valve isn’t properly seated can alter the entire process, forcing the engine to work harder and overheat.
Rough Idle or Clicking Sounds
Your motorcycle engine shouldn’t make any strange sounds, just a throaty rumble as you idle at a stoplight or power through the twisties. However, if you notice your bike makes odd noises, then it’s a cause for concern. A rough or uneven idle indicates the engine is struggling because the valve clearance is off. Alternatively, a clicking sound from the engine suggests the valve components are contacting other parts because the position or timing is off.
Declining Fuel Economy
Motorcycles are incredibly efficient, but a poorly positioned valve can threaten even the best fuel economy. An intake valve that doesn’t have the right amount of lash or clearance doesn’t create the best seal or open and close in sync with the rocker arm or crankshaft. Even slightly off, this poor positioning forces the engine to work harder and burn more fuel, forcing you to spend more at the pump.
Planning Your Motorcycle Valve Service
What rider doesn’t want their bike to perform its best as they chase the horizon? As riders, it’s our responsibility to ensure our motorcycles have what they need to perform well. Manufacturers make our jobs easier by outlining the recommended motorcycle service interval, including essentials like valve service and valve adjustment.
You don’t have to spend much time thinking about the valves on your motorcycle when you climb in the saddle. Instead, it’s essential to know the role the valves play and recognize signs of trouble. This awareness is the key to heightening your bike’s performance and extending the life and longevity of your engine by ensuring the operating conditions are ideal. Fortunately, we’re always here to help and can walk you through a DIY valve adjustment or handle the service from the convenience of our service center.
