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Sea-Doo Reed Valves Explained [+Common Problems & Fixes]

Sea-Doo Reed Valves Explained [+Common Problems & Fixes]

Sea-Doo reed valves refer to the intake valves on 2-stroke 947 and 951 Rotax engines. Besides the more advanced rotary valves, reed valves were the most commonly used intake valve system on vintage 2-stroke Sea-Doos.

If you want to find out more about reed valves and their fixes, this post is for you.

We at JetDrift have compiled all you need to know under one roof!

What are Reed Valves on a Sea-Doo?

The idea of reed valves has been around for a long time. They are commonly used on 2-stroke powersport vehicles and Sea-Doos are no exception.

Often referred to as “reeds,” reed valves represent a one-way valve system that is mounted between the carburetor and the crankcase. The main idea behind these valves is to control the intake of the air-fuel mixture. They ensure increased engine power, better fuel consumption, and less blow back from the carbs.

Let’s get down to the nitty-gritty and talk about how they work in detail!

How do Sea-Doo Reed Valves Work?

Reed valves are designed to restrict the flow of the air-fuel mixture to a single direction. During operation, these check valves open and close according to pressure changes.

The heart of this system is the reed valve flaps, which are often referred to as reed valve petals.

These petals are thin flexible sheets that bend during their operation. Back in the day, they were made of metal but their aftermarket replacements are typically made of more durable carbon fiber.

Reed valve petals are nestled in a metal cage, which is placed in the intake port. The other end of the assembly is attached to the carb via an intake boot.

The purpose of these valve petals is to allow the air-fuel mixture to flow from the carburetor to the crankcase. Since the mixture can only move in one direction, the petals effectively prevent the mixture from flowing back to the carb.

Interestingly enough, the reed valve assembly is a completely passive device, meaning that it doesn’t have any moving components.

You may be wondering, how the valve petals open and close.

This is where pressure change comes into play.

When the piston in the cylinder moves upwards it creates a vacuum in the crankcase. This vacuum opens the reed valve and allows the fuel-air mixture to enter the engine.

When the piston is moving down, it causes the vacuum in the crankcase to change into pressure. This pressure forces the valves closed, which keeps the fuel-air mixture inside the engine.

Compared to outdated piston ports, reed valves have many advantages, like increased engine power and better fuel consumption. What’s more, they reduce blow back issues or fouled spark plugs.

Drawbacks?

One of the main downsides of reed valves is their restrictive design. Since they are mounted in the  direction of the airflow, their petals stand in the way of the fuel-air mixture flowing into the engine.

Because of this, the majority of 2-stroke Sea-Doos feature the more advanced rotary valve system. Unlike the restrictive reeds, this valve system leaves the intake ports completely open.

In return, it features a much more complex design, which could fail in many different ways.

Because of this, many riders prefer reed valve Sea-Doos over rotary valve models, since this valve system is much simpler and doesn’t have any moving parts.

Hence, it’s more reliable and requires much less attention.

Which Sea-Doos Have Reed Valves?

As a rule of thumb, all 947 and 951 Sea-Doo models use reed valve engines, and many of them enjoy innovative RAVE exhaust valves as well. These units were 2-stroke, twin-cylinder Rotax engines that housed two reed valve assemblies.

Bombardier manufactured Sea-doos with these engines from 1997 through 2007, and many of them still run on the waters.

Based on our research, the list of reed valve Sea-Doos is as follows:

1997 GSX Limited

1998 GSX Limited

1998 GTX Limited

1998 GTX RFI

1998 XP Limited

1999 GSX Limited

1999 GTX Limited

1999 XP Limited

2000 GTX

2000 GTX DI

2000 LRV

2000 RX

2000 RX DI

2000 XP

2001 GTX

2001 GTX DI

2001 LRV

2001 RX

2001 RX DI

2001 RX X

2001 XP

2002 GTX

2002 GTX DI

2002 LRV DI

2002 RX

2002 RX DI

2002 VSP-L

2002 XP

2003 GTX DI

2003 LRV DI

2003 RX DI

2003 VSP-L

2003 XP DI

2004 XP DI

2006 3D 947 DI

2007 3D 947 DI

2000 Sportster LE

2001 Sportster LE

2002 Sportster LE

2003 Sportster LE

2004 Sportster LE DI

2005 Sportster LE DI

2006 Sportster LE DI

Besides Sea-Doos, Bombardier used its reed valve Rotax engines in their Ski-Doo snowmobiles as well.

Unfortunately, reed valves didn’t work well in sub-zero environments, which is why they were replaced by the more effective rotary valve system on Ski-Doos.

How do You Know if Your Jet Ski Reed Valve is Bad?

There could be many symptoms of bad reed valves on a Sea-Doo, but the most common ones are arguably as follows:

·         Engine is hard to start

·         Engine sputters and misfires

·         Carburetors are hard to tune (especially at the bottom end)

·         Poor bottom-end power

If your reed valve Sea-Doo has malfunctions like these, it’s time to inspect its valves.

To inspect the reed valves on a Sea-Doo you have to remove the entire valve assembly from the intake port.

Then, turn it towards the light and look into the cage through the carb boot. If the valves are in good condition, you shouldn’t see any light.

If you do, it’s a sign that the valve petals are chipped or broken, which are the most common issues of this valve configuration.

Also, don’t forget to inspect the valve petals manually and visually.

Note that each reed valve system has a minor reflux, but if the petals are damaged to any extent, it’s time to replace them.

If they are not replaced in time, there’s always a chance that the engine will suck in a broken valve petal, resulting in a major engine damage.

What Causes Reed Valve Failure?

Reed valve petals are considered wear items, so they will crack and break over time.

Just imagine it, these thin plates bend countless times, essentially at every single revolution of the engine.

Therefore, it is no surprise that they will wear out and break off and have to be replaced periodically.

 

How to Fix Sea-Doo Reed Valves

Unfortunately, Sea-Doo reed valves can’t be fixed once they get damaged. Instead, they should be replaced with aftermarket units.

If you have to fix your reed valves, you can choose between two options.

The cheaper way is to only replace the petals, which are often sold separately. More advanced performance petals are made of carbon fiber for maximum durability.

However, many riders replace the whole assembly including the cage and the carb boot, which are also available on the aftermarket.

Don’t forget that you will need two complete assemblies, one for each intake port.

Conclusion

Sea-Doo’s reed valves are simple check intake valves designed to control the flow of the fuel-air mixture.

The reed valve assembly features a metal cage and sets of thin steel petals. This entire unit is nestled in the intake port and connected to the carb with a boot.

Reed valves instantly became popular thanks to their simplicity and passive design.

They don’t house any moving parts since the valve petals are opened and closed by the fluctuating pressure in the crankcase.

The main idea behind reed valves is to restrict the flow of the mixture to a single direction, from the carburetor to the crankshaft. This advanced design ensures better fuel efficiency, more engine power, and fewer backfiring issues.

Bombardier used a reed valve system in the Rotax 947 and 951 2-stroke twin engines. These power sources were commonly used in Sea-Doos manufactured from 1997 through 2007.