The Yamaha Raptor 250 was one of the top five selling sport ATVs in 2008. With its low retail cost of $4199, it was popular not only with youth riders, but adults too!  Despite only having a 249cc air-cooled powerplant, the little Raptor 250 has a lightweight chassis, peppy throttle response and an overall smooth ride. We have claimed it one of the most fun ATVs ever built.

For any popular ATV, the aftermarket has a whole slew of components built to improve upon looks, handling and performance. For this test we turned to companies like Duncan Racing, Roll Design and Elka to lay the groundwork for us. Here are the results.

To build any race or play quad properly, you need to look at what the ATV might be lacking. The Raptor 250 is an excellent entry-level machine, but to win on the track, motor and suspension upgrades are needed. It also goes for the 180+ pound rider looking to grab the reigns of the small Yamaha. You will find that the stock unit could use a bit more power and some cushion to support your fat behind.

Duncan Racing put the life into our Yamaha Raptor 250. Duncan’s National 250cc Kit is available for $1499. This includes a complete Fat Boy 4 stainless exhaust system, SERDI valve seat machining, oversize cam intake valve, and heavy-duty valve springs with titanium retainers and shortened Valve Guides. The meat of the kit includes a 12:1 JE Piston ($225 alone), a camshaft and cylinder head mods that include porting and valve seating. The exhaust muffler is made of brushed aluminum. There is an anodized blue, red or black color option for an additional $125.

To feed the fresh motor more air, the stock air box was cut to fit a Pro Design Pro Flow Kit, which sells for $169. Along with a Vortex X10 Programmable CDI ($449), and after a couple of brief warm up cycles, the quad is ready to ride.

(Left) The $110 QuadTech seat cover provided plenty of grip, and looks oh so cool. (Middle) The AC Racing nerfbars are equipped with sharp kick-up foot pegs, and worked great for a technical MX track. (Right) The new Roll Design front end is lighter than the stock setup, so a GPR stabilizer was installed.

Up front, the stock steering stem was replaced with a +1-inch Roll Design setup ($349). Roll Design’s MX Lobo II A-Arms ($1999) grace the Raptor 250. These arms are two inches wider than stock, and use the stock spindles. The kit includes Roll A-arms, Elka Sport Shocks and a Crown Front Brakeline kit. This machine features a $200 Elite shock upgrade. To finish off the front, a GPR “Low Boy” steering stabilizer ($449) was installed.
Out back, the stock swingarm was used with an Elka Elite shock ($1045), and a +2-inch Dominator II Axle ($449).
The stock sprockets were replaced with Sunstar sprockets with the stock gearing of 14/36. Duncan Racing suggests a 15-tooth counter sprocket, but as of right now it is unavailable from the aftermarket. We’ll keep you updated.
ITP Quad Cross tires (20×7­x10/18x8x8), and Douglas Ultimate Solid Center front and rear beadlock wheels were installed. These wheels were dipped in blue and look oh so sweet!
Renthal/CR HI handlebars ($94.95) were installed onto the new Roll stem, with a Motion Pro Vortex twist throttle  ($32.95), Works Connection clutch perch ($129.95), Tag grips ($12.95) and a Pro Design tether kill switch ($34.95)
To add protection to the stock unit, aluminum Pro Nerf/peg/Heel guards ($289), and a Duncan Racing pro front bumper ($179) was installed as well.
To cap off the clean look of this Raptor 250, Duncan Racing graphics ($79.99) and a Quad Tech seat cover ($110) were installed.

(Left) Roll Design’s $2000 MX Lobo II A-Arms grace the Raptor 250. They are two inches wider than stock, and use the stock spindles. (Right) A Motion Pro Vortex twist throttle, Vortex ignition switch, Works Connection clutch perch, Tag grips and a Pro Design tether kill switch were installed on Renthal/CR HI handlebars. All of which bolted right up to a Roll Design steering stem.

To give this little Raptor a true world test, we headed down to MileStone MX Park. This is the same track where we see Yamaha test riders doing R&D work on a regular basis.  They probably did some of the initial development for the stock Raptor 250 here. The track is tight with medium sized double jumps and tabletops, tacky dirt and banked corners.  This venue is perfect for smaller sport machines. For comparison, we brought along a nearly stock Raptor equipped with a GYTR slip-on exhaust system.
To get an immediate feeling of how the Duncan engine compared, we did a series of drag races. Starting in either first or second, the Duncan Raptor got the jump and steadily pulled away down the straight. This is great considering that the smaller 18-inch tires on the Duncan machine provide lower gearing than the 19-inch stockers. Drag race results due to increased rpm and over rev will be further improved when the aftermarket gets around to building a larger countershaft sprocket.
Traveling around the track we noticed another positive aspect of this engine build; a somewhat quiet exhaust. The Duncan set up is about two dB’s quieter than the GYTR system. The track ended up being a second and third gear track.

Not only was the Duncan motor more powerful in a straight line, it helped us get over the jumps easier and out of the corners quicker. Another asset of this project quad was the Vortex ignition with its multiple maps and dual-position shift on the fly programs. After our first stint on the track we started adjusting the programmer and found that we could use one ignition setting for most of the track then flip a switch for a power boost or more over rev to clear the large tabletop in the center of the track. This same technology help former Duncan sponsored rider Doug Eichner win many championships over the years.

Compared to the stocker, this quad cornered like it was on rails. Where the stock machine would two-wheel in the tight turns and lift the front end at the exits of the corners, the Duncan/Roll/Elka machine stayed planted in every corner and handled like a go-kart. It carved the corners without out a hint of push, and would only step out in the rear with body input from the pilot.

That glued to the ground sensation can also be attributed to the ITP Quad Cross tire selection. The tread pattern of this new tire provides sandpaper-like traction without being overly soft or wearing out prematurely. After running a couple of tanks of fuel through the Raptor, the tires showed very little signs of wear.
Speaking of fuel, Duncan recommends Sunoco high-octane brand fuel for optimum performance. However, the slightly higher compression engine will run on high-octane pump gas (premium), or better yet a 50/50 mixture of pump gas and race fuel.

The Roll/Elka suspension system not only gave the Raptor near perfect corning, bump absorption was pillow soft. After the first few laps we did have to stiffen up the high-speed compression clicker four turns at both ends. We left the low speed neutral since the corning was so perfect and there were no braking or acceleration bumps on this particular track.

Our settings helped us feel comfortable over-jumping the smaller tabletops and casing the large double. You could do no wrong with this machine. It would go where you pointed it and take any correct or bad hit any of our riders would make.

The Tag CR High Handlebar and steering stem selection was a good choice and took away the somewhat cramped feel the stock Raptor has. You could probably save some money by just replacing the stock bars to reach that same comfort level.  Extra-wide aggressive foot pegs were a nice touch as well.

For throttle control, the Vortex quick turn throttle was a perfect fit for this machine if you prefer a twist, although the stock thumb throttle is not that bad.
A Quad Tech seat cover was a very appealing part of the project and we have QT products on all of our hopped-up vehicles. However, after spending time on the new YFZ450R with its T-shaped seat, we wish the aftermarket would come out with a miniature T-shaped seat for the Raptor 250.

Duncan racing is one of the best ATV engine builders in the country, and is considered near the top worldwide. With over two thousand dealers and 30-day engine and one year guarantee on their exhaust systems, you are getting more service than most companies can even offer.

At $1500 for the engine package with exhaust, and $2000 for the Roll/Elka front end, we knew it was possible to turn the little Raptor into a competitive machine. Not only with other Raptors, but also with 400’s and for some 450’s on a novice level. Any lighter weight teenager would find more than enough power and suspension with this package.

The other odds and ends like the steering stem, seat cover, twist throttle and clutch perch are a nice touch, but they can be purchased at a later date if you are on a tight budget.

If you are looking for more power in the dunes, more torque in the woods or faster speeds on the track, the Duncan National kit will do just that. For even more serious power, a 280cc National Kit ($1849) and 280cc Big Bore Kit ($575) are available. These include a 280cc piston (12-1 or 10-1), head gasket and a cylinder strip-bore-replate (customer must send stock cylinder to DRI for modification upgrade). Duncan also sells a X2 Camshaft for $179, and a 33mm Keihin FCR carb kit for $499. Give Duncan Racing a call at (866) 379-7223.  And if you are a customer on the other side of the world from Duncan’s San Diego headquarters, shop on line at www.duncanracing. com.


DUNCAN RACING (866) 379-7223
ITP TIRES (909) 390-1905
IMS PRODUCTS (800) 237-9906
MOTION PRO (650) 594-9600
QUAD TECH (949) 859-7823
WORKS CONNECTION (530) 642-9488

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