Yamaha Raptor 660 Problems - Our Investigation of the Worst Issues

Your Raptor 660 is a sporty ATV fitted with a single-cylinder, four-stroke engine with five valves. The Yamaha Raptor's design is key to allowing the ATV to perform impressively in all riding conditions. Yamaha put out the 660 Raptors from the early 2000s until 2005 when it replaced it with the Raptor 700.

If you are looking to maintain your Raptor 660 or buy a used one, this article is the practical guide you have been searching for. It will discuss the common problems reported by other Raptor 660 owners and highlight the various solutions or preventative measures appropriate for each. 

Is Your Raptor 660 Engine Idling Too High?

Does your ATV feel as though someone is flooring the gas? As a proud owner of the Yamaha Raptor 660, it can be very confusing when your quad idles very high and you can't figure out why.

Your first step should be inspecting your carb for signs of damage. Where you find damage and defects due to wear and tear, it is advisable to consult a certified auto repair expert to diagnose whether the issue calls for a repair or replacement. 

If the problem persists, hold on to your patience because the problem may not be as severe as you suspect. You should inspect your Raptor 660 closer to ensure the throttle cable is free. Inspect whether the throttle cable is getting stuck on any surface when you move the handlebars.

Since this problem is associated with the throttle cable assembly, you should take the cover of the throttle cable off the left carb. When you watch the actions of the cable, you will be able to see if the throttle cam is being moved as the bars move or if it is free. 

Is Your Raptor 660's Starter Motor Turning Yet The Engine Motor Is Not?

You may have noticed that it is not easy to start your Raptor 660. At times, your starter motor may turn, but the engine motor fails to engage. You may also have experienced pressing the starter while in neutral and hearing the relay engaging, yet your starter motor doesn't make a sound.

Your Raptor 660 may also be pretty hard to start when the engine is cold, but when it has warmed up, it runs well and will start quickly after it is turned off. 

• Valve Clearance

After encountering these problems, make sure that your valve clearance is accurate. This is because the Raptors can get cranky when the valves are inaccurate. Riders are advised to refer to the prescribed valve clearance rate in their user manual and measure their valves to compare.

If your valve clearance is not within the recommended rates, you can adjust them yourself or rely on a certified auto repair expert. If your valve clearance keeps adjusting, it may be necessary to check the valves for signs of damage or wear and tear.

• Battery Defects

Your Raptor 660 may also be experiencing challenges starting due to a faulty battery. If the battery causes the problem, it is easy to detect it with a voltmeter. Riders without voltmeters in their tool kit can rent one at their local hardware store to test their battery. If, after fully charging your battery, it reads below 9.5V instead of the normal range of 12V to 13V, it is the lead suspect in your starting problems.

A battery you cannot charge fully is likely to drain faster and fail to produce the electricity needed to keep your motor humming. You are advised to replace a defective battery as soon as possible. Where your battery is reading within the prescribed range, you can remove all the cable connections and clean the surfaces and screws, and nuts before tightening them securely.

• A Defective Starter

Another likely cause can be the wiring leading to your starter or the starter itself. When you measure the current reading from the output terminal and input terminal and determine that it's lower at the output and high at the input, the problem is the relay.

If it is high at the output terminal and lowers at the input terminal, the problem can be caused by starter connections. If it's low everywhere, it can be the battery connections or the battery, and you may require more troubleshooting. 

Riders are advised to consult a qualified auto repair expert for advice on whether to purchase a new starter or simply improve the wiring to their starter. 

Your Raptor 660's Engine Idles Great But Sputters And Spits When You Press Throttle

Whenever your Yamaha Raptor 660 is idling with no issue, but after applying some throttle, the engine spits and sputters; any of these lead suspects could cause the problem:

• RPM limiters

Most Yamaha Raptor 660 come pre-installed with three RPM limiters. These are maximum RPM, reverse RPM, and parking brake (PB) RPM limiters. If either of the PB or reverse circuits fails, the CDI invokes these limiters causing the engine to cough, backfire, spit, and even sometimes the engine may die when you apply the throttle.

• Reverse limiter

The engine has a circular 1-pin switch found under the output socket and acts as the reverse switch. This switch is usually grounded except when the bike is in reverse. It is connected to the CDI with a green wire with a white stripe.

If the wire is at the ground, the CDI (computer) assumes the bike is in reverse and consequently turns on the reverse limiter and reverse indicator light.

There are several reasons for the switch to fail, and these include; 

1. A damaged switch
2. Unplugged reverse switch wire
3. Corrosion and dirt at the wire connections
4. A broken reverse wire

All these reasons can fool the CDI into assuming that the bike is in reverse and, in turn, activating the RPM limiter and the reverse light.

• Parking brake limiter

The Yamaha Raptor 660 has a switch located on the clutch perch for sensing when you engage the parking brake. Whenever the parking brake is on, the switch is engaged. The black wire is ground.

If the CDI senses that the green with yellow wire is at the ground state, the RPM limiter is turned on. The PB limiter can also cause the engine to choke and putter. Look for potential damages that can lead to the wire shorting with the ground or the CDI.

Your Raptor 660 is Not Starting

When you are trying to start your engine, and the starter cranks the engine, and you smell gas, but it won't start, here are some causes of the problem: 

• Your ATV is getting not getting any spark
• Your ATV is getting a weak spark
• Your ATV has fuel system defects.
• Your ATV has trouble getting enough air.
• Your battery is dead or drained
• Your ATV kills switch is corroded or defective.

Where your Raptor 660 engine won't start, your first step should be to ensure that you have enough fuel and air. Next, you should check your spark plug. To test it, you need to first ground the metal body of the plug to your engine, crank the starter and look for a blue/white, consistent spark across the gap.

If the gap is not present, the problem could be from the internal short of the stator in the stator winding leading to the CDI. This failure is tested by unplugging the rectifier. When you unplug the rectifier, the short pulling of the CDI signal will allow the ignition voltage to be produced.

If it works, it means that your stator is the one that needs to be replaced. You can leave the unplugged rectifier indefinitely with no damage to your bike. But this also means that your battery won't be charged.

Proper Maintenance of the Raptor 660

Dutiful maintenance is the best way to avoid all the challenges listed above. Riders who have adequately cared for the Raptor 660s have had off-road adventures with them for years. To ensure the longevity of your Raptor 660, adhere to these simple rules:

• Stick to your recommended maintenance schedule per the user manual
• Create a personal maintenance schedule that is suited to your usage. Schedule regular cleaning, inspection, and oil changes.
• Avoid over-customizing your ATV to allow all components to function optimally without additional strain.
• Get any customization performed by a licensed auto repair expert
• Use your ATV within the recommended road and weight limits
• Drive your ATV carefully
• Purchase high-quality replacement parts that are compatible with your ATV

Final words

In summary, the worst issues of the Raptor 660 are less common and severe than imagined. Riders who care for their ATVs may never face most of the problems listed. Take up the challenge of avoiding the repair shop by going through your user manual and learning to care for your Raptor 660.

This is the best way to ensure you and your Raptor spend as much time on the road and have as many adventures as possible.