Why do 2 stroke engines always have a reed valve?

Reed valve allows the mixture to move in only one direction – from the carburetor to the crankcase. It prevents the mixture from moving back to the carburetor. In the effect reed valve improves reloading of the combustion chamber with fresh air-fuel mixture. This improves power output of modern two stroke engines.

Do all 2 strokes have reed valves?

Since a bad reed valve can be the cause of a variety of problems, knowing if you even have these can be useful – not all 2 stroke engines use reed valves. If it just “dumps” into crankcase, like diametrically opposite cylinder, most likely it’s got a reed-valve. …

What are the advantages of a reed valve?

Reed valves allow you have the maximum possible intake duration, without significant blowback. So a reed-valve bike can potentially be MUCH more efficient than rotary, because you aren’t going to be pushing mixture back out of the engine through the intake.

Will a 2 stroke run without reeds?

No, they won’t run without reeds. As for backfiring through the carburetor, very unlikely unless there was something like a glowing piece of carbon somewhere in the cylinder to light the fuel/air charge before the piston closed the intake port. You should be able to get away with reusing the reed block gasket.

Do reed valves make a difference?

More rigid reed valves usually help the engine at high rpm, because they avoid resonance and, by returning more easily to their starting position, they avoid the play of fuel from the crankshaft.

Do reed valves affect compression?

NO, the reed valve, in 2-cycle engines, does not effect compression in the cylinder. It will, however effect the pumping action in the crankcase. The fuel/air charge will not be effectively drawn in and compressed in the crankcase if the reed valve is malfunctioning.

How long do reed valves last?

Generally, reed valve petals should be replaced every 100-150 hours. Engines with reed valves that are failing can present symptoms of hesitation during acceleration. The engine may fail to respond to the increased fuel flow and then jump forward as the gas is finally ignited.

What will bad reed valves do?

Failing reed valves can result in reduced power at what should be cruising speeds. However, failing reed valves reduces the fuel and air mixture. This results in fuel being dumped into the carburetor with no flame to ignite it. The result is reduced power.

Will bad reeds cause no start?

Most outboards will wear the reeds and produce a bit of pre-loading, never seen that make one hard to start. If a reed is cracked or broken, it will idle horribly, have no hole shot, but run well on top end.

How often should reed valves be replaced?

Reed valve petals wear down over time and should be checked every 15 to 20 engine work hours. If the reed valve petals are chipped, frayed, or no longer create an adequate seal, they should be replaced. There is no standard timeframe to use when changing your reed valve petals.

What running problems can reed valves cause?

If the reed valves are cracked, they may not open all the way, which will reduce the amount of oxygen that gets into the engine to mix with the fuel. The result is a rough idling engine that sounds like it is on the verge of dying.

Why do two stroke engines use reed valves?

Two-stroke engines have no need for the valvetrain that we find in a four-stroke engine; the movement of the piston past carefully shaped ports controls the admission of charge to the cylinders. Fresh charge is drawn into the crankcases where it is compressed by the descending piston.

What are the different types of 2 stroke intakes?

A quick explanation of the three most common 2 stroke intake types. Reed valve, rotary valve and piston controlled induction “piston port”. Support me on Patreon!

What kind of valve is a reed valve?

The reed valve – sometimes called a leaf valve – is a profiled flat component that sits across an aperture in its closed position. These are commonly used in pairs on a V-shaped block, as shown in the photo here. The opening of the reed valve is restrained by a ‘reed stop’ that prevents the reed opening so much that it becomes permanently deformed.

Why are motorcycles turning away from two stroke induction?

Just as the motorcycle race classes and the bike manufacturers are turning away from two-strokes due to emissions, other companies are embracing the technology.