TRX450ER in the Desert

At the height of the sport quad reign, the TRX450ER was one of the most popular machines on the market. The TRX could be found at every track, sand dune area, or riding park. Since its inception in 2004, the TRX450 has gone through several changes over the years – including the addition of an e-start and an engine overhaul that gave the machine a bigger bore, shorter stroke, a more aggressive cam profile, and ultimately added over 8 horsepower to the engine. Production may have ended in 2014 for the TRX450, but it still remains a sought-after machine to this day due to its reliability and overall fun factor. We decided to take this 2008 TRX450ER and make it even better. Check it out.

Engine and Exhaust

We began the build by taking a closer look at the engine. Although Honda made some significant improvements to the TRX450 motor in the 2006 re-design to give it more power, we still felt like the engine could use some waking up. The first thing we did to turn up the excitement was to add the Cylinder Works Big Bore Cylinder Kit. The big bore kit comes ready to bolt on with the cylinder, gaskets, and piston kit, and allows for a bigger bore and shorter stroke. It is relatively easy to install and gave us that edge we were looking for by boosting the power and performance to around 475cc’s, while still retaining the reliability of the Honda 450 engine.

Cylinder Works Big Bore Kit on the TRX450ER

Once we added the big bore kit, we wanted to help the engine breathe a little better to continue to improve the power. The stock airbox lid on the TRX is pretty closed off, so we added the Pro-Tec Moflow Airbox Lid to help increase airflow to the engine. With its OEM fitment and laser-cut design, the Moflow Airbox Lid clips into place right on top of the stock airbox and allows a lot more air to come into the engine for optimal performance. The mesh screen accommodates the increased airflow while also acting as a prefilter for the air filter by keeping larger particles and debris out.

Next, we switched out the stock exhaust for the Lexx MXe Slip-On Silencer with Mid-Pipe. Not only is the Lexx silencer affordable, it also looks good, increases performance, and is tunable. The changeable tips can take it from a race exhaust with a 46 mm race tip to a spark arrested exhaust with the USFA approved screen-type quiet core insert.

Lexx Exhaust on the TRX450ER

Because the 2008 TRX450ER is carbureted, we also had to do some work on the jets since we made some significant changes to the engine, intake and exhaust. The Dynojet Jet Kit is a machine-specific kit that comes with all of the jets and needles we needed to re-jet the machine and get the proper fuel-air mixture for the 450ER to run optimally with the mods we made.


After addressing performance and power, we turned our focus on protection – for both the rider and the machine. The first change we made was getting rid of the stock heel guards and foot pegs and replacing them with Tusk Foot Peg Nerf Bars with Heel Guards.

Tusk Nerf Bars with Heel Guards on the TRX450ER

Nerf bars offer several different elements of protection for the rider. First, they offer a much larger platform for the rider’s foot that includes a solid, oversize aluminum peg to really plant your feet, and webbing to extend the overall footprint and prevent debris from kicking up. Another protection aspect of nerf bars that is especially helpful in racing situations is the ability to prevent another quad’s tire from entering the space between your front and rear tires, potentially causing major harm or damage to you or your ATV. And finally, the wrap around, aluminum heel guard replaces the stock plastic heel guards to really create a solid barrier of protection to prevent your heel or ankle from getting caught in the rear tire.

PowerMadd Handguards on the TRX450ER

Handguards are a great addition to offer a little more rider protection. We added the PowerMadd Sentinel Handguards to the TRX450ER that not only look great on the build, but offer durable, functional protection for both the rider’s hands and the levers. We also mounted a Tusk Power Pull Tether Kill Switch up by the handlebars that attaches to the rider as well so that in the event that they unexpectedly come off of the machine, the engine will cut and the ATV won’t go far.

Tusk Comp Series Front Bumper on the TRX450ER

On the front of the ATV we installed the Tusk Comp Series Aluminum Front Bumper to help add some protection, and to help with leverage of lifting or loading the machine, or getting it unstuck out on the trail. Underneath the machine we bolted up the Ricochet Full Chassis Skid Plate and the Ricochet Bullet Swing Arm Guard. A lack of both clearance and protection under ATVs can leave the machine vulnerable, especially out on the trail where rocks or logs might be a concern, so a skid plate and swing arm guard are really important to protect the lower hanging components and slide over obstacles without causing damage.

Skid Plate and Swingarm Guard on TRX450ER


As far as handling is concerned, we went with Odi components in our build. For the handlebars, we installed the Odi 7/8” Handlebar in the ATV Racer Bend, and then added the Odi ATV Half Waffle Lock-On Grips in the Ruffian design to the bars as well. The lock-on grips are always a great addition for ease of install, durability, and overall comfort, and the half-waffle MX compound design keeps with the sport feel of the machine. To round out handling, we installed the Tusk Handlebar Risers to give the bars a little bit more height.

TRX450ER Build in Action

Tires and Drive Components

When it comes to sport quad tires, the ITP Holeshot line has been among the top contenders on the market for years for its performance, traction and durability. We went with the ITP Holeshot XC in a 22×7-10 for the front, and the ITP Holeshot GNCC in a 20×10-9 on the aluminum wheels for the rear. The GNCC model of the Holeshot is ideal for more varied-terrain trails or racing, and makes for a great all-around sport tire.

Holeshot Tires on the TRX450ER

We upgraded the drive components with a new Primary Drive 520 ORH Gold X-Ring Chain. We also added the Tusk Adjustable Width Racing Axle to the machine. The Tusk axle is made with a chromoly hardened steel and chrome plating finish to not only offer superior strength, but also a sleek look as well. It is also adjustable from 1 ½” to 3 ½” over the stock axle width, so it gives you a little more room to work with and to widen out your machine.

Tusk Adjustable Width Racing Axle on the TRX450ER

Graphics, Seat Cover, and Extras

As with any great build, it is never strictly about performance – it’s about making the machine look just as sweet as the mods you made to it. This TRX450ER was no exception. We went through and installed a custom Attack Graphics Full ATV Graphics Kit, as well as an Attack Graphics Gripper Seat Cover to really enhance the look of the machine. It’s not just the overall graphics that make the look either, which is why we added a handful of bling parts like the Tusk Billet Aluminum Gas Cap and the Tusk Oil Filler Plug to really make the details pop. For a complete list of all the extras that we added, make sure to check out the parts list below.

Attack Graphics on the TRX450ER


After this build, our TRX450ER is ready to get back out on the track and take its rightful place among the top reigning sport quads.


Tell Us What You Think

Did our mods give this machine the power within its potential? Let us know in the comments below.

Parts Available at Rocky Mountain ATV/MC
Cylinder Works Big Bore Cylinder Kit 477cc Pro-Tec Moflow Airbox Lid Lexx MXe Slip-On Silencer with Mid-Pipe
2008 TRX450ER Build: Cylinder Works Big Bore Cylinder Kit 2008 TRX450ER Build: Pro-Tec Moflow Airbox Lid 2008 TRX450ER Build: Lexx MXe Slip-On Silencer with Mid-Pipe
Dynojet Jet Kit Tusk Foot Peg Nerf Bars With Heel Guards PowerMadd Sentinel Handguards
2008 TRX450ER Build: Dynojet Jet Kit 2008 TRX450ER Build: Tusk Foot Peg Nerf Bars with Heel Guards 2008 TRX450ER Build: PowerMadd Sentinel Handguards
Tusk Comp Series Aluminum Front Bumper Tusk Power Pull Tether Kill Switch Ricochet Full Chassis Skid Plate
2008 TRX450ER Build: Tusk Comp Series Aluminum Bumper 2008 TRX450ER Build: Tusk Power Pull Tether Kill Switch 2008 TRX450ER Build: Ricochet Full Chassis Skid Plate
Ricochet Bullet Swing Arm Guard Odi 7/8″ Handlebar Odi ATV Half Waffle Lock-On Grips
2008 TRX450ER Build: Ricochet Bullet Swing Arm Guard 2008 TRX450ER Build: Odi 7/8" Handlebars 2008 TRX450ER Build: Odi ATV Half Waffle Lock-On Grips
Tusk Handlebar Risers ITP Holeshot XC Tire ITP Holeshot GNCC Tire
2008 TRX450ER Build: Tusk Handlebar Risers 2008 TRX450ER Build: ITP Holeshot XC Tire 2008 TRX450ER Build: ITP Holeshot GNCC Tire
Primary Drive 520 ORH Gold X-Ring Chain Tusk Adjustable Width Racing Axle Attack Graphics Custom Stealth ATV Graphics Kit
2008 TRX450ER Build: Primary Drive 520 ORH Gold X-Ring Chain 2008 TRX450ER Build: Tusk Adjustable Width Racing Axle 2008 TRX450ER Build: Attack Graphics Custom Stealth Complete ATV Graphics
Attack Graphics Gripper Seat Cover Tusk Billet Aluminum Gas Cap Tusk Oil Filler Plug
2008 TRX450ER Build: Attack Graphics Gripper Seat Cover 2008 TRX450ER Build: Tusk Billet Aluminum Gas Cap 2008 TRX450ER Build: Tusk Oil Filler Plug