A loose motorcycle chain can cause many problems, but the most common are typically as follows:
- Chain lash (chain starts slapping and getting noisy)
- Chain jumping (skipping sprocket teeth)
- The chain and sprockets wear out faster
- Chain breaks or gets stuck between the rear sprocket and the swingarm (locking up the rear wheel)
If you want to find out more about these issues and their remedies, you are in the right place.
We at PowerSportsGuide have compiled all you need to know about loose motorcycle chains into this post!
What Happens if a Motorcycle Chain is Loose?
Motorcycle Chain Lash
A loose chain on a motorcycle often causes a symptom known as “chain lash.” The lash of a motorcycle chain means that it’s slapping and causing a lot of noise, especially when you start to accelerate or decelerate. This is because too much slack allows the chain to contact the swingarm or the chain guard. Besides the noise, this also causes a jerky feeling at virtually every acceleration.
The explanation for this is that the chain on top of the rear sprocket is always tight while the chain loop at the bottom is rather loose.
When you close the throttle the engine brake forces the chain to work in reverse.
This sudden change in the direction typically leads to a slapping chain. In contrast when you accelerate, the engine power jerks the loosend chain on the top.
The looser the chain the more noticeable these symptoms are!
Why is My Motorcycle Chain Jumping?
A jumping motorcycle chain occurs when the chain “jumps” over sprocket teeth. In other words, the chain skips sprocket teeth and then it engages with the sprocket again. That’s why this malfunction is also known as “chain skipping.” The most common reasons for a jumping motorcycle chain are typically too much chain slack and an extremely worn rear sprocket.
If the sprocket teeth are “hooked” (look like little waves) or worn out, the chain can jump over them much easier.
In extreme cases, the rollers can slide over these waves causing the chain to jump.
Although chain skipping on a motorcycle is very rare, it is not impossible.
The Chain and Sprockets Wear Out Faster
Besides the above-mentioned issues, a loose chain wears out sooner and can damage the sprockets too.
The increased friction between the chain and the sprockets eats their surfaces much faster, while the jerks caused by the chain can bend the sprocket teeth.
Because of these concerns, you always have to pay attention to proper chain maintenance. Besides the periodical cleaning and lubrication, it’s recommended that you check the chain tension as well.
Chain Comes off the Sprocket or Breaks
It’s a lesser-known fact that the worst outcome of a loose motorcycle chain is an accident! If the chain is too loose there’s always a risk of it coming off the rear sprocket. If this happens (and you are lucky), the chain will run freely, leaving you without any engine power. But in the worst-case scenario, the chain can get stuck between the swingarm and the sprocket, which causes the rear wheel to lock up. Unfortunately, this typically ends in an accident.
What’s more, if a motorcycle chain is loose, there’s a higher chance that the chain will break.
If there’s too much slack in the chain, during an aggressive acceleration the front sprocket can strongly jerk the chain. If the chain is worn out, this force can break its weakest link.
In most cases, the broken chain simply drops to the ground and you lose power. However, the chain can also wrap around the rear sprocket causing a jam.
This jam can also lead to a blocked rear wheel, which usually results in a fall as you can see in this video:
Another concern is that when the chain breaks it can act as a whip, damaging your bike and even hitting your leg. Fortunately, these accidents happen extremely rarely!
How do You Fix a Loose Motorcycle Chain?
To fix a loose motorcycle chain you have to adjust its tension by moving the rear wheel backwards. To do this, you have to loosen the rear axle nuts and tighten the chain adjusters until you reach the required chain slack. If the tensioners are completely tightened and your chain is still loose, it probably means that it’s too long and a link has to be removed.
Besides, keep in mind that chains become looser and looser during their life. If you feel your chain is too loose and it’s slapping a lot, you should consider replacing it.
Here’s a great video on how to fix a loose motorcycle chain:
How Loose Should Your Motorcycle Chain Be?
How loose should your motorcycle chain be? This is a typical question of many beginner riders, and the answer is that it depends. The desired chain slack, just like the proper tightening method, is clearly stated in your bike’s manual. If you’re looking for some ballpark figures on how loose a motorcycle chain should be, the rule of thumb is that the slack of street bike chains should be about 1.2 – 1.6 inches while dirt bikes usually require 1.4 – 2.0 inches of slack, Cycle World reports.
Again, these are pretty average numbers. The exact chain settings vary from one bike to the next.
Therefore, always check your service manual before you do any maintenance on your bike!
Why Does My Motorcycle Chain Keep Getting Loose?
There are many reasons why a motorcycle chain keeps getting loose, but the most common ones are as follows:
- Loosened rear axle nuts or chain tension nuts (most common issues)
- Wrong chain alignment
- Worn out sprockets
- A spacer is missing somewhere
- The chain is brand new (they are prone to getting loose)
- The chain is too old and needs to be replaced
- Your chain is the wrong size (a chain is always specific to the sprocket set!)
- You’ve drastically changed your bike’s gear ratio (which wears out the chain much faster)
- You ride your bike too hard (aggressive accelerations/stunts put a lot of stress on the chain)
Many times, it’s not the chain that stretches but its rollers and pins begin to wear out, which simply causes more slack in the chain!
Is it Safe to Ride a Motorcycle with a Loose Chain?
No, as you already know, riding a motorcycle with a loose chain is never safe. A loosened chain can break or get off the sprocket, which can lead to an accident! Always make sure that your chain is tightened and maintained properly to avoid these issues.
As a takeaway, we’ve compiled the most frequent questions with the shortest possible answers!
What happens if a motorcycle chain is loose?
If your motorcycle chain is loose, it’s typically slapping, rattling, or making other noises, especially when the direction of the force changes (a.k.a. chain slash). Too much slack in the chain causes the sprockets to wear out faster.
The worst outcome of a loosed chain is when it breaks or comes off and gets stuck between the rear sprocket and the swingarm. This may end in a locked up rear wheel!
Why is my motorcycle chain jumping?
The chain on a motorcycle jumps when it’s too loose and the sprocket teeth are hooked. Chain jumping (a.k.a. skipping) occurs when the chain is skipping teeth on the rear sprocket.
How do you fix a loose motorcycle chain?
You can simply fix a loose motorcycle chain by adjusting its tension. If the chain is too long and you can’t tighten it more with the adjusters, you may want to remove a link. If the chain is worn out it has to be replaced to avoid further damage.
How loose should your motorcycle chain be?
The desired chain slack varies from one model to the next, but it’s always described in the service manual.
Is it safe to ride a motorcycle with a loose chain?
No, never ride your motorcycle with a loose chain to stay safe!
How do I know if my motorcycle chain is too loose?
You can tell if the chain on your motorcycle is too loose by checking its tension. But in many cases, there are many noticeable signs of a loosened chain like a noisy or a slapping chain.
Why does my motorcycle chain have a tight spot?
Motorcycle chains always feature tight spots as they wear unevenly. Therefore, these tight spots in the chain are typically considered normal.
Disclaimer: This post is for general informational purposes only. Before you do any maintenance on your bike, always read its manual and follow the manufacturer’s recommendations!