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Honda 400ex Specs and Performance


Honda TRX 400EX Specs and Review: Honda Motors Co. manufactured the Honda 400EX ATV model from 1999 until 2009. It shares a 397cc engine design with their XR 400R ATV. The TRX 400EX also sports a sturdy steel frame with removable sub-frame and cast aluminum swing-arms that offer exceptional rigidity. Triple disc brakes provide the TRX 400EX ATV with much needed stopping power and an aggressive body style compliments the drive line well.

Honda 400ex ATV

Honda 400EX specs include a high performance 397cc dry-sump, air-cooled, four-stroke single cylinder engine. A radial four valve combustion chamber (RFVC) takes care of creating horsepower. Honda paid particular attention to camshaft timing in order to meet the tough requirements set for torque and usable horsepower. The motor has dual intake and dual exhaust ports for maximum engine efficiency. The TRX400EX has a five-speed transmission with Reverse to round out it's arsenal of go fast.

The extremely popular and fast 400EX ATV remained a top enthusiast choice for many years and is finding it's stride in the collectible market now, it's a fun and sturdy little ATV. Honda released their all new TRX 450R ATV model and stopped production of the TRX 400 in 2009. It may become harder to find high performance TRX400ex parts, but not too hard, the TRX400EX was a runaway hit and many were produced. Parts are often found on auction sites by ATV parts resellers, here's an example of some listings.

Honda 400EX Specs

  • Model Years : 1999 - 2009
  • Model name: TRX400EX
  • Engine : RFVC, dry-sump, 1-cylinder, 4-stroke
  • Displacement : 397 cc
  • Bore and Stroke : 85 x 70 mm
  • Carb : 38 mm piston-valve with accelerator pump
  • Cooling : Air-cooled
  • Starter : Electric
  • Clutch : Manual
  • Transmission : 5-speed with reverse
  • Final Drive : O-ring-sealed chain
  • Ignition : CD with electronic advance
  • Suspension Front : Independent double-wishbone with Showa shocks, 5-position spring-preload adjustabillity, 8.2 inches of travel Rear : Pro-Link fully-adjustable single Showa shock, with 9.1 inches of travel
  • Brakes Front : Dual hydraulic 174 mm discs Rear : Single 220 mm disc
  • Tires Front : 22 x 7-10 knobby radial Rear : 20 x 10-9 knobby radial
  • Length : 72.2 inches
  • Width : 45.3 inches
  • Height : 43.7 inches
  • Wheelbase : 48.4 inches
  • Seat Height : 31.9 inches
  • Turning Radius : 10.5 feet
  • Ground Clearance : 4.3 inches
  • 400EX Weight : 386 lbs.
  • Fuel Capacity : 2.6 gallons including 0.4 gallon reserve
  • Colors : Black, Red
  • 1999 Honda 400ex specs were virtually unchanged through 2009

Additional information about the Honda 400EX ATV

It's model name is "Sportrax" and base manufacturer retail price(MSRP) was set a little above $5000 during the middle of it's run. 400EX enthusiasts today refer to it as the best ATV ever made. While you could do wheelies and jumps along with your friends the chances were that your ATV would still run when theirs needed repairs.

Another factor that made the Honda 400EX popular is the fact it was equally comfortable on the track and on the trails. It's clutch was beginner friendly and overall it's a great sporty little package even today. The only downside to it's design, and it's not a huge downside, is that it could not reverse. The drive-train only moves in one direction, forward.

In stock brand new condition the Honda 400EX was clocked at roughly 64 MPH top speed although it took a little bit of coaxing to reach that speed. Common performance upgrades included Elka shocks and ITP bead-locks. I know because I see a lot of used 400EX quads still sporting them. Overall value and durability along with performance and customization has given the 400EX a spot in the "best ATV ever made" competition, to many it's the champ. Check out the ATV Brands page to see how the TRX400EX model helped secure top spot for Honda in our popularity poll.

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