Kawasaki Bayou 300 Common Problems — Locating and Fixing

The Kawasaki Bayou 300 is one of the most fondly remembered recreational utility vehicles. With hydraulic disk brakes, a 700-Ib haulage capacity, and a dual-mode differential, the Bayou 300 remains one of the most powerful four-wheel recreational vehicles ever made. 

If we consider that the Bayou 300 has been around since the mid-80s, then it is easy to appreciate the quad bike's market dominance. 

Although Kawasaki's first four-wheeled concept remains an enigma, it can be quite problematic. Most notable is the 2002 recall of the KLF300B and KLF300C models where the axle nut was not torqued to specifications. As a result, this forced the hub off the axle shaft. 

That said, there are seven common problems Bayou 300 owners face. We will show you how to find and fix them with ease. 

1. Ignition key switch fault

Even though the Bayou 300 is an outdoorsy vehicle, it can be susceptible to the fallout of harsh weather conditions. Water and dirt can become trapped in your ignition switch rusting the spring responsible for putting pressure on the contact points. 

This action will lead to the malfunctioning of the voltage regulator responsible for supplying current at 14.5VDC. Where the voltage received exceeds the normal range, it can burn many components within the quad bike such as the glass light bulbs and cables.

The solution to an ignition key switch fault depends on whether the fault is at its early stages or the contacts are completely rusted. For an early-stage diagnosis, the appropriate action will be to clean the contacts of early rust with a contact cleaner. Also, ensure that your ignition is kept in good condition at all times. You can achieve this with the aid of graffiti grease. Simply dip your keys in the grease before starting the ignition. 

In instances where the ignition switch contact has already garnered excess rust, then you need a new key switch. Since no electronics are involved in the function of this component, buying an aftermarket alternative is not a bad idea. 

2. Engine Misfires or Backfires

A common challenge many have with the Kawasaki Bayou 300 is engine misfiring. There are four possible causes for this malady:

• An improperly timed fuel pump
• A poorly tuned carburetor
• Inaccurate valve timing
• Unusually low idle screw setting

Your priority once you have identified this problem is performing leak down and compression tests. 

• Improperly Timed Fuel Pump

Improperly timing your fuel pump will reduce your Bayou 300's engine performance and can trigger engine misfire among other problems. It is therefore advisable to check your user manual for the optimal pressure for your fuel pump to ensure it spurts fuel exactly when it should. 

Additionally, check the vacuum valve that is responsible for controlling the fuel pump pressure to ensure that it is not screwed too tight. Not that an abrupt reduction of speed can also cause a surge in your bike's exhaust system. 

• Poorly Tuned Carburetor or Inaccurate Valve Timing

If your carburetor is poorly tuned or valve timing is off, your quad can misfire or backfire into the carb. The latter can damage your carburetor boot in the long run. To know if your valve timing is off, listen for a strange popping sound when:

• Entering the fifth gear;
• Releasing the throttle;
• At speeds lesser than 20 mph.

These are all signs that your carburetor is too rich and you may notice thick black soot at the base. There are numerous possible causes of a malfunctioning carburetor. One may be a bad petcock. 

Check that your petcock still slows down the rate of fuel by turning it halfway. Most Bayou 300 use the Keihin CVK carburetor. The challenge with this carb is that the float needle jet cannot be removed. 

The best solution is to change carburetors to an alternative aftermarket solution like the Mikuni carbs which have proven to be far more reliable. However, note that such a change will require correctly jetting the carb, and changing the throttle cable to make it fit.

• How to correct valve timing

The first step to carrying out a valve adjustment on your Kawasaki Bayou 300 is to remove the plastic covering above the gas tank. 

Next, remove the gas tank and the valve covers - including that of the exhaust - before taking out the spark plug. The spark plug usually prevents the top dead center from being accessed. 

Once you have found the top dead center, recoil your pull start slowly to find the "T" timing mark that sits on the compression stroke.

Make the correct adjustments with the feeler tool, preferably to a 0.10mm to 0.15mm or 0.20mm to 0.25mm as required by your bike. While doing this recoil your pull start to assess clearances. 

If satisfied with your adjustments, try starting the engine to see how it runs. You do not have to fix back the fuel tank before doing so-the carburetor float should contain enough fuel to keep your engine running for a few minutes before you recouple your quad. 

• Unusually low idle screw setting

An unusually low idle screw setting can cause your carburetor to run rich. It can also trigger backfiring. This is because this setting runs counter to the intentions of the Bayou 300 factory settings. 

• Alternative fixes

Other alternative fixes to an engine misfire on Kawasaki Bayou 300 include switching your Bayou air filter for a better alternative, fixing up a Dynajet kit, or upgrading the snorkel.

3. Engine Knocking Noise

An engine knocking noise is keenly tied to a faulty ignition key switch leading to a damaged voltage regulator. Although on other vehicles this sound is a sign of serious mechanical trouble, the primary cause is the voltage regulator. 

It is responsible for converting the current generated at the stator into DC current that can charge the battery and power the bike's electrical components. In order to determine if the rectifier is the cause of the problem simply remove it and see whether or not the engine goes back to sounding normal. 

4. Stalling Issues

Your engine is stalling if it loses fire and dies within a few minutes of starting. There are many causes of an engine stall. The most common trigger is improper or restricted fuel flow, often resulting from intense riding. It is possible to pull the plugs twisting the handlebars back and forth. 

Quads also tend to stall more frequently when they are not ridden often. To resolve this primary cause, you have to inspect your plugs yourself. Your electrical plugs are located ahead of the fuel tank, underneath the bike handlebars. 

Therefore, you will have to remove the tank's plastic coverings to get access to them. If it is a case of a loose wire connection between the plug's cables, you can secure the wires with an electrical tape or cable tie. By doing so, you will prevent future occurrences. 

• Breaching Fording Depth

Another cause of a stall occurs when you breach the fording depth of your quad bike. The Kawasaki Bayou 300 has a fording depth of eight inches, the equivalent of 20cm. Stay within the fording depth to prevent the wetting of vehicle components or the building up of moisture.

• Other causes of stalling issues

There are many other causes of an engine stall. They include:

• Bad fuel lines
• Damaged filters
• Improper vacuum tightening
• Malfunctioning ignition CDI box
• Spoilt stator

Any of these issues can cause an engine stall. So check that these parts are working properly. Tell-tale signs of faulty CDI or stator are surface rust on their connections, and occasional overheating. 

5. Excessive Tire Wear

One of the major challenges of owning a Bayou 300 4WD model is preventing tire wear. Because, these 4x4 are in persistent pursuit of grip, they get worn out faster from traction. As such you need to be prepared to invest in regular wheel balancing and associated professional fees. 

Another key solution is to pick a suitable tire for your terrain. All tires are made of distinct compounds. Some allow more grip due to their lighter compounds. Although they are the safest, they tend to wear easily. On the other hand, the heavier tires last longer but provide less grip. As such, they can be a safety concern for many. 

The best course of action is to select tires that strike a balance between safety and durability. Furthermore, you can also reduce your throttle action to put less pressure on your tires and avoid wearing them out rapidly. 

6. Low-powered Engine

The Bayou 300cc engine is not the most powerful ATV engine in the market; it is not expected to be otherwise. It is ideal for flat terrains and for light activity. Thus, it is wrong to expect this low-power engine to haul heavy loads or plow snow. For such activities or terrains, it is better to look for a stronger ATV. However, if you are keen on adding a bit of boost to your carburetor 300cc engine, you can make the following changes:

• Replace your existing filters with high airflow filters to suck in a greater air volume.
• Replace the carburetor needle to allow more gas to pass through.
• Get a more powerful exhaust replacement for the stock exhaust. Your new system should allow the free exit of air from the engine.

7. Transmission Challenges

A major challenge Kawasaki owners face is the difficulty in gear selection or locating the neutral gear. Transmission fixes are best left to professionals especially when it involves adjusting gears and forks. 

However, a common cause of a transmission challenge that can be fixed is a stuck reverse cable. This cable connects the engine to the lever. Unplug the cable and start the ignition to determine the source of the problem. Reroute or if necessary, replace the cable if the gear becomes normal again. Other less common causes of transmission issues are worn-out shift drum springs and cams.