From its inception in 2000 through its last production-year in 2004, the Yamaha Raptor 660 was looked at as the ultimate sport ATV.
Though it saw a rather short production run, it was the most popular ATV on the market at the time before giving way to the next great Yamaha sport quad.
And while many more modern sport models have entered the market since the early 2000’s, the Raptor 660 is still right up there with the fastest of them all these years later.
So how fast is a Raptor 660?
And what should you consider before buying one?
This guide will answer all of your questions around the Raptor 660’s speed, performance, and attributes including:
- Specs, key features and performance
- Pros and cons
- Top speed
- Stock vs. modified top speed
- The speed limiter and whether you can bypass it
- The top 660-specific mods to increase the speed and horsepower
Specs, Key Features & Performance
Engine & Drivetrain
Powered by a big-bore 660 cc single cylinder engine with a max output of around 36 HP, the Raptor 660 offers impressive low-end torque and excellent throttle response throughout its five gears.
This German-made engine is the same one used in the MZ Baghira dirt bike of the same era, and was selected to give the Raptor 660 the combination of speed, torque, and power that the competition couldn’t match at the time.
This model is also equipped with a 33 mm Mikuni dual carburetor that provides the air-to-fuel mixture.
The drivetrain consists of a constant-mesh 5-speed manual transmission and wet clutch system, with a secondary chain drive powering the rear wheels.
The 660 offers only 2WD, with both a Forward and Reverse gear.
| Engine Type | 4 Stroke, SOHC |
| Cylinder Arrangement | Single Cylinder |
| Displacement | 660 cc |
| Engine Cooling | Liquid-Cooled |
| Horsepower | 36 HP |
| Fuel Delivery | Dual 33mm Mikuni Carburetor |
| Fuel Capacity | 3.2 US Gallons |
| Drive System | Chain Drive, 2WD |
| Transmission Type | Manual, Constant Mesh 5-Speed |
Suspension
The Raptor 660 makes use of an independent double wishbone with preload adjustment and coil spring/oil damper shocks in front.
In the rear, there’s a swing arm suspension with rebound, compression and preload adjustment along with gas coil spring/oil damper shocks.
One of the main complaints with this model is the lack of adjustability with the front and rear shocks, which can lead to the ride feeling too stiff or too soft without a good middle ground for some riders.
The suspension setup offers an impressive 9.06 inches of travel up front and 8.66 inches of travel in the rear.
This suspension system contributes to a good turning radius of 10.8 feet and an impressive 10.4 inches of ground clearance, making the Raptor 660 an excellent trail option.
| Wheelbase | 49 in |
| Ground Clearance | 10.4 in |
| Front Suspension | Independent Double Wishbone |
| Rear Suspension | Swing Arm |
| Travel | Front – 9.06 in, Rear – 8.66 in |
Tires & Brakes
The Raptor 660 came equipped with stock Dunlop 21 x 7-10 tires in front and Dunlop 20 x 10-9 tires in the rear, mounted on steel rims.
These tires do provide sufficient grip in most terrains, but for those who ride mostly trails you’ll likely want to upgrade to something more aggressive.
The braking system consists of dual hydraulic disc brakes in front and a single hydraulic disc brake in the rear, which together provide plenty of stopping power.
The front brakes are operated by a single lever on the right handlebar, while the rear brakes are operated by a foot pedal in the right footwell area.
| Front Tires | 21 x 7-10 (Dunlop KT331) |
| Rear Tires | 20 x 10-9 (Dunlop KT335) |
| Wheels | Steel |
| Front Brake Type | Dual Hydraulic Disc |
| Rear Brake Type | Hydraulic Disc |
Dimensions
As a pure sport model, the Raptor 660 is quite compact from an overall size and weight perspective for its class.
But at 398 lbs dry weight, it’s a bit heavy for a pure sport ATV which makes it a little hard to handle while trail riding, especially for smaller or lighter riders.
With its compact build style, it can easily snake through tighter wooded areas and qualifies to ride 50-inch width or less BLM trails.
| Length | 72 in |
| Width | 43.3 in |
| Height | 45.3 in |
| Seat Height | 33.9 in |
| Dry Weight | 398 lbs |
Pros & Cons
As an older model, there has been plenty of time for this model’s main strengths and weaknesses to take shape among owners.
Per owner feedback, here are the Raptor 660’s main pros and cons.
Pros
- Have the speed to outrun just about any sport ATV out there.
- Won’t find better low end grunt or overall power in a pure sport model.
- Excellent cornering ability.
- Despite their higher stances, excellent engine torque makes it easy to slide the rear around when cornering without the fear of tipping.
- Bulletproof as they come from an overall build perspective, they’ll take a good beating and continue to fire right up.
- 2002+ models offer long gearing and make for less frequent manual shifting.
- Reverse gear comes in handy while trail riding or getting unstuck.
Cons
- Their higher stance means you sit up higher on these models than other sport quads, with some owners likening it to riding on a tractor vs sitting in a sports car.
- With a higher center of gravity, this model can feel unstable and tippy compared to other sport quads.
- The one way bearing on the starter clutch has a tendency to fail and need to be replaced.
- 2000-2001 models are known to have tranny issues, with the dog gears known to break off and the gear spacing being sub-par.
- The carburetor is known to cause issues such as hard starting, rough idling, and backfiring if not cleaned regularly and jetted properly.
- The suspension is looked at as a weak point of this model since the shocks have limited adjustability, making it tough to find a good middle ground between a stiff and soft ride.
- While the lightest quad in its class, it is still pretty heavy for a sport ATV which can make handling on the trail a little tougher.
Raptor 660 Top Speed
Powered by a 660cc single-cylinder engine with a power output of around 36 horsepower, the Raptor 660 top speed is between 72 and 75 mph.
While that top speed range is specific to models still in fully stock form, the top speed of a Raptor 660 can be increased to 85 mph and beyond for those open to making some upgrades.
Though it’s a little top-heavy, this model still makes for one of the best racing quads available today.
Modifications To Improve Speed & Power
There are six common modifications that can be made to the Raptor 660 to improve the power and top-end speed.
- Bypassing the speed limiter
- Upgrading the air intake
- Upgrading the exhaust
- Re-jetting the carburetors
- Adjusting the gear ratio
- Adding big tires
While a couple of these mods will increase the top speed even with the speed limiter in place, to see any substantial gains speed-wise you’ll need to start by outsmarting the speed limiter.
Raptor 660 Speed Limiter
The Raptor 660 contains a speed sensor on its output shaft.
This speed sensor relays the speed of the vehicle to the CDI unit, which will restrict it in 5th gear once it reaches a speed of 75 mph.
The speed sensor is configured with the settings of the Raptor 660’s stock gearing and tires.
So if upgrading these components, the speed limiter will not know this and you’ll be able to reach a higher speed than 75 mph.
That said, even with upgraded tires and gearing, you’ll still likely top out around 80 mph.
For those who want to go faster, you’ll need to find a way to bypass this speed limiter, and there seems to be only one way to do it.
Bypassing the Speed Limiter
The speed sensor essentially amounts to a reluctor wheel that contains a number of teeth, which it uses to measure the vehicle’s speed as it turns.
The only way around this speed limiter is to essentially fool it by grinding away every other tooth on the wheel.
That way, the sensor only sees half the number of teeth and relays to the CDI unit that the output shaft is turning at half the true speed it really is.
The speed sensor wheel sits behind the clutch basket within the clutch case. To access it, you’ll need to remove the clutch side cover.
Simply reinstall it after making the necessary adjustments to the teeth, and your speed sensor will no longer trigger the CDI to restrict the speed to 75 mph.
Upgrading The Air Intake
The intake system is made up of the airbox and air filter, and is responsible for circulating clean air into the Raptor’s engine.
The amount of air circulated into and out of the engine will help determine the amount of power it is able to produce.
The goal of upgrading the air intake system is to maximize the amount of air that can be fed to the engine, which will also determine how much fuel it can be fed.
Similar to other Yamaha sport models, the 660’s factory intake tends to smother the top RPM levels which limits top-end speed.
To eliminate this, owners can consider modifying the stock airbox by either replacing it or removing the airbox lid to enable more airflow, along with upgrading the stock air filter.
If removing the airbox lid, you’ll want to reinstall it for any rides that involve water or when washing your vehicle so the air filter doesn’t get wet.
Highest Recommended Intake Upgrades For Raptor 660:
- Modquad Racing Air Filter
- Pro Design Pro Flow Air Filter Kit
If sticking with the stock airbox and just replacing the air filter, the two best options are a K&N filter or a UNI filter.
K&N filters work great for riding that isn’t dusty. If you do a lot of dusty riding, the UNI filter is your best bet.
Upgrading The Exhaust
When increasing the airflow into the engine, you’ll need to complete the air circulation process by giving this added airflow an efficient exit as well.
This can be achieved by upgrading the stock exhaust system.
An upgraded exhaust should increase the horsepower and torque of the Raptor 660, with added power felt in each of the gears.
And it will provide your Raptor with a much better sound when riding.
Highest Recommended Exhaust Upgrades For Raptor 660:
- Barker’s Exhaust
- Curtis Sparks Exhaust
- HMF Exhaust
- Monster Exhaust
- Yoshimura Exhaust
Each of these exhaust systems differ in their styling and sound, but will increase performance by around the same amount.
You can see how many of them stack up with one another in this exhaust guide.
Re-jetting The Dual Carburetor
With an increase in airflow from an upgraded intake and exhaust, you’ll also need to increase the fuel flow to ensure your air to fuel ratios remain optimal.
Similar to the Yamaha model it replaced, the Raptor 660 is equipped with a dual carburetor.
Re-jetting the dual carburetor in the 660 will help to achieve this increased fuel flow, and is essential in ensuring your engine runs correctly after modifying the intake and/or exhaust systems.
Within each of the two carburetors of the Raptor 660 are three jets that will need to be replaced or adjusted.
Finding the ideal combination of replacements and adjustments to these jets depends upon the specific modifications you’ve made and will likely take some trial and error.
Main Jets
The stock main jet is a size # 140 in the left carburetor and a size #145 in the right carburetor.
It is recommended that owners move to either a # 160 main jet in the left carb and a # 165 in the right carb, or a #170 main jet in the left carb and a # 175 main jet in the right carb.
That said, you may want to purchase a few different main jets between 160 and 220 in size and test them out until you find the best fit.
Pilot Jets
The stock pilot jet in both of the Raptor 660’s carbs is a size 22.5. The ideal replacement size tends to be a move up to a size 25 pilot jet.
You’ll need to replace the pilot jets in both carbs, and may need to test a couple of different sizes as well.
Needle Jet
There is a needle jet located within each of the stock carbs as well, and rather than replacing these they will just need to be adjusted by turning them.
Turning each between one to two full rotations usually nets the best results, but owners should test this out to find the best setting as well.
Adjusting The Gearing
One of the most common ways to increase the top speed of the Raptor 660 is to adjust the gear ratio by swapping out one or both of the stock sprockets.
The Raptor 660 in stock condition is equipped with a 13-tooth front sprocket and 40-tooth rear sprocket.
To increase top-end speed, you’ll want to swap out the front sprocket for a slightly bigger one and potentially swap out the rear sprocket for a slightly smaller one.
Doing so should increase your top speed by 3-6 mph, but will also decrease your low-end torque and acceleration so that your quad doesn’t reach that top end speed quite as fast.
The ideal gear ratio for increasing top end speed without sacrificing much acceleration for the Raptor 660 tends to be moving to a 14-tooth front sprocket and leaving the stock 40-tooth rear sprocket alone.
Adding Bigger Tires
The Raptor 660 is equipped with 21-inch stock tires in the front and 20-inch stock tires in the rear.
For more top-end speed, upgrading to 22 or 23-inch tires in front and 21 or 22-inch tires in back should help your Raptor get a few extra mph.
Conclusion
A fully stock Raptor 660 should reach top speeds of around 71 to 75 mph, topping out due to a speed limiter.
For those who want to go faster, bypassing the speed limiter and making several other modifications can take your quad past the 85 mph mark.
Before you go, check out the following guides for more on some of the fastest Yamaha ATVs in the industry:
