Why Does My ATV Chain Keep Coming Loose? 

So far today, you’ve had to stop your ATV about half a dozen times because the chain keeps coming loose. It’s driving you crazy! Why is this happening?

Your ATV chain is coming loose for these reasons:

  • The chain stretched after use and needs tightening
  • The sprockets or eccentric clamps are worn
  • The sprocket seating is misaligned
  • The chain is old and needs a replacement 

In today’s article, we’ll go through each of the above causes of a loose ATV chain so you can get yours tighter right away. Should you have to install a new ATV chain, we’ll also tell you how to do that, so make sure you keep reading! 

4 Reasons Your ATV Chain Is Loose

The Chain Is Stretched After Use and Needs Tightening

The first reason your ATV drive chain could be so loose is that it’s new. If anything, it’s too new. 

Given its mint status, when the manufacturer first installs a new drive chain on your ATV, you can expect the chain to be tighter than being between a rock and a hard place. 

Then, after riding your ATV a couple of times, the chain begins to loosen. If it loosens too much, it can become slack. That causes the issues you’ve been experiencing now. 

With a screwdriver, a measuring tape, and some sockets or wrenches, head out to your ATV. The vehicle should be parked on even ground, and it should be off when you tinker with it. 

Check the drive chain slack when no one is on the ATV. Then have a buddy sit on your ATV like they’re going to ride it and see if the slack changes. 

To measure the chain slack either way, start at the chain guard or skid plate and go to the middle of the swingarm. 

Open your ATV user manual and confirm the appropriate amount of drive chain slack. Typically, it’s an inch, but it can be as much as an inch and a half, so you have to be sure. Then adjust as needed.

The Sprockets or Eccentric Clamps Are Worn

Next, it’s time to check the sprockets as well as the eccentric clamps.

Your ATV has a front sprocket that spins when you turn over your engine. The transmission triggers the sprocket rotation. 

As the sprocket spins, it tugs on the drive chain. 

That’s the front sprocket. The drive train can also pull on a rear sprocket. When that happens, the rear axle moves, and the wheels of your ATV turn so you can get going. 

Thus, if something is wrong with your ATV’s sprockets, you might have bigger issues than just a loose drive chain. 

If not the sprockets, then it’s time to investigate the condition of the eccentric clamps. 

In some cases, it’s even the castle nut or the cotter pin depending on how old your ATV is and how it was built. 

When these parts wear down, the chain suffers with them. 

In most cases, replacing a loose or damaged nut isn’t all that complicated. 

If you’re having issues with the sprockets, you can either replace those yourself or see your mechanic and let them take care of it.  

Don’t be surprised if the mechanic recommends replacing both the chain and the sprockets so everything works better. We’d recommend you do the same if you’re doing a DIY job. 

The Sprocket Seating Is Misaligned

The sprockets themselves are wheels with teeth along the entirety of the wheel. The teeth act as notches for pulling the drive train. 

Both the front and rear sprockets are installed in housing or seating. 

Should the seating get knocked out of whack, such as through wear and tear or taking a really big jump on your ATV, then that’s going to affect how the sprockets themselves work.

The sprockets might not be able to pull the chain efficiently due to the misalignment, which has led to the chain falling slack.

In some instances, you might be able to push the sprocket seating back into the right position. If not, then the issue might necessitate replacing the entire sprocket, including the housing, to get the slackness of the ATV chain tighter. 

The Chain Is Old and Needs a Replacement 

How long your chain will last is not measured in years but in hours or miles. 

You’ll get anywhere from 700 to 1,500 miles or 110 to 120 hours out of your chain, whichever comes first. Stock chains might last even less time still. 

Have you gone through every troubleshooting method we’ve described in this section? Are all the components in tip-top condition but your chain is still loose?

Then it’s more than likely an issue with the chain itself. Try swapping the chain out for a new one and see if that does the trick. It probably will! 

How to Tighten an ATV Chain 

You’ve decided that the issue with your ATV drive chain necessitates tightening, and you’d like to do it yourself. Here’s how.

First, find the bearing carrier and the adjuster bolt. Some ATVs might have more than one adjuster bolt, so don’t panic if that’s the case for yours.

What if your ATV doesn’t have adjuster bolts at all? That does happen sometimes. 

In that case, then loosen the bearing carrier bolts and look for a hole. This hole is how the sprocket and carrier communicate, so to speak.

Place an Allen key or screwdriver into the hole, turning it to tighten up the rear wheels. They should spin as you do this. 

Check your owner’s manual for the recommended amount of tightness for your ATV chain. If your chain is set too tight, it will cause the sprockets to prematurely wear. Then you’ll have problems all over again. 

For ATVs with an adjuster bolt, take the bearing carrier bolts and loosen them up. Do the same for the adjuster bolt’s jam nuts, but tighten the adjuster bolt itself. 

As you did when adjusting your ATV before, you want to test the slackness of the drive chain both when no one is on your ATV and when someone is sitting on it. 

When you get the correct amount of chain slackness, be sure to tighten the jam bolts and carrier bolts you loosened. Then try riding your ATV and see how it feels. You should be satisfied!

Check out this YouTube tutorial on how to adjust the chain on your ATV.

How to Loosen an ATV Chain

Oops. You hadn’t realized you had set your ATV chain too tight until you checked your sprockets a month later and all the teeth were worn down to almost nothing. 

You don’t want to make that mistake again. How do you loosen a too-tight ATV chain?

Just do everything you did in the last section but in reverse order. In other words, loosen the bearing carrier and adjuster bolts. 

You still want to refer to your ATV’s owner manual to determine the perfect amount of slackness on the chain. Once you have it to that point, you can consider this job done.

What if you’re trying to loosen your drive chain but the adjuster bolts are turned as loose as they can go and the chain still feels too tight? In that case, your chain is too short. 

You’d have to either replace the chain with a longer chain or lengthen your current chain with master links. 

How to Install a New ATV Chain

You need to install a new ATV chain. Although it’s a bit more complicated job, it’s still doable, especially if you know your way around your ATV.

Here are the steps to follow.

Step 1 – Buy a Replacement Chain

ATV and dirt bike chains are available by certain roller diameters, widths, and pitches as follows:

  • 420 chain – 7.75-millimeter roller diameter, 6.35-millimeter width, 12.70-millimeter pitch
  • 428 chain – 8.51-millimeter roller diameter, 7.75-millimeter width, 12.70-millimeter pitch
  • 520 chain – 10.16-millimeter roller diameter, 6.35-millimeter width, 15.88-millimeter pitch
  • 525 chain – 10.16-millimeter roller diameter, 7.85-millimeter width, 15.88-millimeter pitch
  • 530 chain – 10.16-millimeter roller diameter, 9.53-millimeter width, 15.88-millimeter pitch

Check your owner manual to confirm which type of ATV drive chain your vehicle utilizes. More than likely, it’s a 420 chain if yours is a smaller ATV or a 520 if it’s a standard-sized vehicle.

Step 2 – Gather Your Tools

You’ll need an assortment of tools to replace your ATV drive chain, such as:

  • Chain breaker tool
  • Hammer
  • Punch
  • Grinder
  • Chain rivet tool
  • Flat blade screwdriver
  • Pliers

If you don’t already have what you need, then run out to your local home improvement store and stock up.

Step 3 – Remove the Current Chain

You can’t keep the old, stretched drive chain on your ATV anymore, so it’s time for the chain to come off. 

If your chain has been extended with a master link, then you can use your pliers to detach the master link clip and pull the master link off. 

A chain break tool, hammer, or punch will come in handy for stubborn master links that don’t want to detach.

If your drive chain features a riveted master link, then you’ll have to grind the rivets until they’re flat. Then, with your chain break tool, hammer, or punch, remove the chain.

Step 4 – Install the New Chain

The length of your new drive chain should be at least as long as the old one if not longer. 

You can count the old chain’s links one by one and then match up that number with the new chain’s links to ensure the new chain is sufficient.

As you did when adjusting the drive chain, loosen the chain adjusters. Then, take one end of the new chain and place it on the rear sprocket. Repeat that with the other end of the chain.

Attach the master link to the chain if you’re working with a master link. Then add O-rings to any sealed chains and follow that up by installing the master link plate. 

You’ll have to press this onto the mater link using pliers. The grooves of the master link clip should be showing. 

Final Thoughts

An ATV chain that keeps loosening can very quickly distract you when riding. Now that you understand what causes ATV chains to become slack and how to tighten them, you can ensure your ATV is ridable all the time! 

Geoff Southworth

I am a California native and I enjoy all the outdoors has to offer. My latest adventures have been taking the family camping, hiking and surfing.

Recent Posts

outdoortroop-21 outdoortroop-20