How to Adjust & Clean the Chain on a Honda TRX400EX 

A slack chain on your Honda TRX400EX slows down the response of the rear wheels to the throttle/engine and dulls your ATV's performance. 

An overly tight chain on your Honda TRX lifts the rear suspension, which ruins your ATV's handling, and rapidly wears out the chain and sprockets. Along with checking the tank for fuel and the tires for air, inspecting the chain's tension on your TRX400EX should be something you do before every ride.

Print out this guide for reference or watch the video above to familiarize yourself with how to clean and adjust the chain on a Honda TRX400EX.

Honda TRX400EX ATV chain adjust and clean

Tools and Parts Needed - Honda TRX 400 Chain Cleaning and Adjusting

Tools

  • Ratchet and extensions
  • Tape measure
  • Sockets and Allens
  • Screwdriver
  • Brush

Measuring Honda TRX400EX Chain Slack

Step 1. Remove the left rear wheel.

Step 2. Hold a tape measure next to the drive chain above the rear swingarm, and about two-thirds of the way back between the front and rear sprockets.

Honda TRX400 chain replacement slack

Step 3. Raise the chain up and push it down to measure the amount of slack. The correct chain slack for a 2007 Honda TRX400EX is about 1⅜ inches.

Adjusting Honda TRX400EX Chain Slack

Step 1. Loosen the four pinch bolts at the rear of the axle hub.

Honda TR400EX chain slack adjustment

Step 2. Because the centerline of the hub is offset, it will either increase or decrease the distance between the front and rear sprockets as the hub is rotated, thus adding or reducing the tension on the chain.

To tighten the chain, put a socket or robust screwdriver into one of the slots in the side of the hub, and rotate the hub clockwise as viewed from the left side of the ATV.

To loosen the chain, put a socket or robust screwdriver into one of the slots in the side of the hub and rotate the hub counterclockwise, as viewed from the left side of the ATV.

Honda TRX400 drive chain adjustment

Step 3. Measure the chain slack again, and continue adjusting the chain until it is at the right tension.

Honda TRX400EX correct chain slack adjustment

Inspecting Honda TRX400EX Chain and Sprockets

Step 1. Examine the chain for kinks, damaged links, damaged pins or damaged rollers.

Step 2. Examine the lower chain guide, found in the bottom chain cover. If the guide is worn, it must be replaced. 

Step 3. Examine the forward chain guide, located over the front of the swingarm. If the guide is worn, it must be replaced.

Honda TRX 400 chain and sprockets

Step 4. Examine the front and rear sprockets for wear. If the sprocket teeth have become long and pointed, or if any of the teeth are cracked or missing completely, replace the sprocket.

PRO TIP: If you need to replace either the sprockets or the chain, then replace all three parts together. A new chain on old sprockets, or a new sprocket combined with an old chain will quickly wear out the new part to the point it will need replacing again. 

Cleaning Honda TRX400EX Chain and Sprockets

Step 1. Thoroughly coat the chain and sprockets with chain cleaner. Rotate the rear wheel to move the chain and sprockets so every bit of them is coated, and then leave the cleaner to penetrate the dirt for about half a minute or so.

PRO TIP: Keeping your TRX400EXs chain clean and lubed will prevent the chain guides from wearing.

Honda TRX400EX chain cleaning

Step 2. Rotate the rear wheel again, and use a brush to remove the dirt and debris from the chain. Brush the chain's inner and outer plates, the pins, and the tops and bottoms of the rollers.

Step 3. Wash the chain cleaner off the sprockets and chain with water, and dry them with a rag or shop towel.

Step 4. Thoroughly coat the chain and sprockets in chain lube. Once again, rotate the rear wheel to move the chain and sprockets so every inch of them is coated.

Honda TRX400 chain lube

PRO TIP: Always use a quality chain lube instead of regular oil. Chain lube is designed and manufactured to cling to a chain revolving at high speed, and provide long-term lubrication and protection. Oil is too thin, and will therefore be flung off the chain when it's moving at high speed.

Adjusting and cleaning your Honda TRX400EX chain is essential because it will extend the life of the chain, chain guides and sprockets, and save you money on replacement parts. If you find that you need to replace the drive chain on your Honda TRX while cleaning and inspecting it, watch the video below to learn how to get it done. 

 

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