Build It: A Cross Country Racer on a Budget

Many times people get the misconception that you have to spend upwards of $25,000 to build a first-class race machine. While it's true the top racers' rides tend to be the most expensive out there, you don't have to spend that much money to enjoy a competitive and reliable race-ready machine.

To prove the point, we decided to build a functional yet clean-looking woods racing machine without breaking the bank. We began with a well-used '99 Honda Sportrax 400EX as our base machine. Our goal was to transform it into a respectable racer that any serious competitor would be proud to call his own.

STAGE 1: MOTOR
To get our project bike up and running, we turned to Mickey Dunlap of Four Stroke Tech (FST) for some advice and motor work. Dunlap has an extensive background in cross country racing and has worked with many of the top racers in the country. In order to minimize our costs, he suggested we start by mildly massaging the motor to coax a little more power from it, then turn our attention to setting up the chassis to handle better in the woods.

For our motor, we went with one of FST's 426 bore kits. We resleeved the cylinder (giving it a thicker cylinder wall), which allows for an overbore of .040 inch. FST's piston kit for the 426 motor has a taller deck height, and that allows you to run the stock cylinder base gasket and a thin head gasket. The stock liner for the 426 piston can be bored out if your budget won't allow for resleeving.

Most aftermarket pistons for the 400EX are made to the same specs as far as deck height is concerned. The pistons are usually about .040 inch short from the top of the wrist pin to the top of the timing edge of the piston. To set up a motor properly, you should have a .040-inch squish-band area around the outside of the piston, which allows for the best burn rate across the top of the piston. This also helps to create a "cool quench area" around the outside of the piston dome to avoid preignition.

To achieve this tolerance with an aftermarket piston, FST recommends you replace the cylinder base gasket with some of Honda's high-temp silicone seal. Dunlap also suggests using a thinner head gasket to meet the .040-inch deck height. You also gain a slight amount of compression by doing this. Right now, the motor is running roughly 11:1, so all we have to do is fuel up with high-octane pump gas.

While the motor was apart, we threw in a set of special cams to allow for removal of the cylinder base gasket. Doing so naturally causes the cam timing to retard between five and seven degrees, so FST designed a new cam kit to advance the timing.

The 400EX has a decent head as far as flow goes, so we simply chose to get a good three-angle valve job and blueprint port and flow work for reasons of economy. By using a billet cam and FST's secondary oil cooler, the oil going into the head is roughly 40 to 50 degrees cooler. This virtually eliminates having to harden the rocker arms. If your rocker arms are already worn, either replace them or harden them. If you are planning on using a regrind cam, you should harden the rocker arms.

Valve springs are always recommended for any cam you put into a 400EX, and we added new ones to ours. Even though you may not need stiffer valve springs for higher-lift cams, it is still good to use them to increase seat pressure so the valve doesn't bounce as it comes back to rest on the valve seat. This is very important to keeping the valves from wearing out prematurely or ultimately breaking.

For good throttle response, the stock headpipe is used in conjunction with a White Brothers slip-on exhaust. This combo keeps the peak power and torque between 2000 and 7000 rpm. In addition, Dunlap modified the stock black box to eliminate the rev-limiter. FST also offers another version that has all the same timing but moves the rev limit an additional 2000 rpm higher.

STAGE 2: SUSPENSION
Next up was to dial in the suspension for racing. Since just about every top racer stresses the importance of having good suspension, this is the one area where we put the most money into our project.

We turned to Elka Suspension for a set of its midrange Sport & Racing shocks. Now a pair of its new adjustable-compression, self-sagging-device, triple-rate shocks with a piggyback reservoir sit up front. In the rear is an adjustable-compression/ rebound, dual-rate setup with remote reservoir.

The shocks drop the machine by approximately 2 to 3 inches overall, which helps lower the EX's center of gravity. All this and a 2-inch gain in travel up front with a 1.4-inch gain in the rear! The ride is much smoother than stock, and with the new shocks in place we could take on the roughest of tracks without worrying about our suspension. The price for a new set of shocks might be a bit of a setback for most racers on a budget, but there is no other mod out there that can transform a stock machine into a true racer like this.

STAGE 3: LOOKS AND PROTECTION
With all the time and effort going into making the EX run faster and handle better, we also wanted to make it look the part. Our next stop was to add a set of Maier's shiny new plastic fenders front and rear with a custom-fit Suzuki Z400 nosepiece. A set of Ceet Racing/FST team graphics was also added, and the bike really started to shape up into a team-replica racer.

After the fenders were bolted on, we turned our attention to the finishing touches. On went a full complement of AC Racing nerf bars (with Pro-Pegs), skids and bumper, Renthal bar and, last but not least, a set of Maxxis Razr tires mounted on Douglas wheels.

PERFORMANCE
In the end, we spent roughly $4500-plus on building our "budget" cross country racer. That may sound like a lot of money, but when you factor in that you can pick up a good used 400EX right now for around $3500, you're still forking over only $8000 for a full-blown racer! The question in our minds was how much of a transformation did the machine undergo?

A spin at Dunlap's makeshift cross country track gave us an answer fairly fast (no pun intended). We were astounded at the performance gain. First off, the motor had an amazing amount of usable torque. We left it in second and third gear for most of the track, and that's all we needed to keep the machine chugging along at speed. It's much faster than the stocker by far! As a matter of fact, after we handed off the EX to one of Dunlap's team riders for the photo shoot, he came back with a big smile on his face--he couldn't believe how strong the 426 was compared with some of FST's more wild, higher-displacement kits.

As far as the handling was concerned, the difference was night and day. The stock Honda is no slouch in the handling department, but with the new Elka shocks on board, our 400EX was transformed into a top-notch handling machine.

If you're looking to get into racing or simply update yesterday's latest and greatest into a vastly improved machine, you can't go wrong with the route we took.