Is valve clearance necessary?

Valve clearances are important, but having them done by your dealer can be very expensive; it’s one of the main reasons a lot of bikes are traded in. But ignore them at your peril as over time your engine can be seriously damaged.

What is intake valve lash?

Valve lash is a small gap between the valvetrain components. It allows the metal parts to expand as they warm up without moving the valves. When the camshaft moves the lifter, it must take up the lash before the valve actually moves.

Where is the Lash on the intake valve?

When the exhaust valve begins to open, this places the intake lifter on the same cylinder on the base circle of the intake lobe. This allows you to set the lash or preload on the intake lobe. Then if you turn the engine roughly 1½ revolutions, the intake valve will begin its lift cycle.

How do you adjust the exhaust valve lash?

When the exhaust valve just begins to open on the first cylinder in the firing order, adjust the intake valve by loosening the adjusting nut slightly while spinning the pushrod until you feel lash in the rocker arm. Tighten the adjusting nut until the slack is taken out of the rocker arm and pushrod.

How does hot valve lash affect engine performance?

Using Valve Lash to “Tune” Engine Performance. For example, by reducing the amount of (hot) valve lash, the valve will open slightly sooner, provide slightly more lift (valve opening), and will close slightly later. This makes the camshaft look bigger to the engine, due to this slight increase of duration and lift.

What does the Lash mean on a GY6 engine?

Valve “lash” is the technical name for the gap between the valve and tappet. The lash is critical to a healthy running engine. Too little lash and you’ll see starting problems and reliability issues. Too much lash will reduce power and potentially ruin the valve. If you’ve just replaced the camshaft, make sure it’s properly timed .

When to set the intake and exhaust Lash?

EO/IC rule (Exhaust Opening and Intake Closing). Set the intake valve lash when the exhaust valve is beginning to open. This will put the intake lifter at the base circle which is where you want it to be. Then set the exhaust valve lash when the intake valve is about halfway down on the closing side.

Can you adjust the Lash on an exhaust valve?

Now the exhaust valve can be adjusted. When all of the intake and exhaust valves have been set with the proper lash, it is common for all the top engine builders to perform a double check by rotating the engine and checking each valve again, starting from the first cylinder in the firing order.

How big is the Lash on a car engine?

Let’s take for example, that your engine has a cam with .500-inch valve lift. If you set the lash at .020-inch, it actually only opens the valve a total of .480 inch (the first .020 inch of movement is used to take up the lash).

Is valve clearance necessary?