Despite all the tightening and adjustments you have made, the motorcycle chain has become slack again, is it?
Your motorcycle chain becomes loose again and again.
Sometimes, the chain is so much loosened that it can practically hit the swing arm.
This situation can apply not just to an old worn-out chain but can also appear in a new chain and sprocket.
So, here’s why the motorcycle chain keeps getting loose:
The chain and sprockets are most likely worn-out and damaged.
A new chain can also become loose if the rear axle is stripped and cannot be tightened enough or a spacer is missing.
Sometimes, rust on the chain can cause the loosening too.
Let us look into these reasons one by one.
Reasons for the motorcycle chain to become loose
As discussed above, here are the main causes for the chain to keep getting loosened:
#1. Worn-out chain and sprocket
A worn-out or damaged chain sprocket can cause your motorcycle chain to become loose frequently.
Even if you tighten the chain, it will loosen up from time to time.
So, how do you check whether the chain sprocket has indeed worn-out?
Fortunately, checking chain drive components for wear and damage is easy since it can be inspected visually.
All you need to do is pull the chain away from the rear end of the sprocket from the rear wheel.
Now examine the pulled sprocket for any wear and tear.
Usually, if the sprocket is worn-out you will see about half a tooth of the sprocket.
A good-conditioned chain will wrap around the sprocket tightly and will not be easy to pull away.
Repeat the above exercise for a few more sprockets at various parts of the chain.
Kind of like a sampling study.
If you see worn-out sprockets most of the times, it is time for you to replace your old chain with a new one.
#2. Rust in the chain
Just like checking for the wear in your chain, you also need to check for rust.
A rusty chain and sprocket are another cause for a loosened chain in your motorcycle.
So, how to check for rust then?
It is similar to how you check for wear and damage in the chain.
Spin the rear wheel to see whether the chain sprockets maintain the same amount of tension throughout the time.
You need to examine the entire length of the chain to check for any signs of rust and damage.
If you find any of the teeth are chipped away or filled with rust, then again it is time to replace the old chain with a new one.
#3. Rear axle is stripped
Stripped rear axle is the most common cause for the motorcycle chain to become loose.
This likely situation can be easily checked and if found to be the culprit, can also be easily repaired.
Here’s what you need to do:
Inspect the threads on both the axle nut and the threads on the axle to see whether they are mangled or rounded off.
Another way to assess the problem is to see whether the stripping is happening by checking the tension in the chain when tightening.
If the chain reaches a maximum tightening point and never gets harder, then it surely looks like your rear axle is stripped.
Effects of a loose chain
Now, let us look into the effects of a loose chain on your motorcycle.
First, a loose chain will create jarring noises whenever the chain runs over the sprockets.
Eventually, this might lead to the chain getting out of the sprocket, which in turn might prove dangerous for the rider.
Next, a loose chain will also result in loosening the rollers on the inside of the chain.
Furthermore, the rings might get worn-out and get damaged quickly if left unchecked for a long time.
So, it is imperative for you to keep the chain in precise tension and diagnose the motorcycle if you have a loose chain.
Since we now know the cause-and-effect scenario, let us look into the remedy.
Tighten the chain
For a loosened chain, the first fix is to adjust the slack and tighten the chain.
Before tightening, measure how loose the chain is and check the manual for the desired slack.
Only then, start tightening the chain.
Loosen the rear axle bolts.
Next, use the adjuster bolts to tighten the chain.
Once the chain is tightened to the required slack, tighten both axle bolts at the same markings.
For a detailed step-by-step guide, here is our post on tightening the chain.
Replace the chain
If the chain is loosening because of rust or because the sprockets have worn-out, then the solution is to replace the motorcycle chain with a new one.
If you are aware of the process of replacing an old chain with a new one, then you can easily do it yourself.
Else, you can dial up your mechanic or the dealer for the chain replacement.
Repair or change the rear axle nut
If it is the stripped rear axle that is causing the chain to get loose again and again, then working on the chain won’t work.
Since the rear axle is stripped, you need to either repair or replace the rear axle nuts.
The axle nuts are located on either side of the rear wheel.
Check which of these 2 axle nuts is stripped.
If it’s some simple strip, you can tighten the nuts.
But if the threads are damaged, you have to replace the axle nut entirely.
It’s better to take your motorcycle to a mechanic or the dealer in case the rear axle nut is stripped.
So, how to prevent your motorcycle chain from loosening frequently?
First and foremost, make sure the chain is clean.
You can use a simple chain cleaner like WD-40 to spray on the chain.
Let the dirt loosen up and then clean the chain with a rag cloth.
Second, lubricate the chain regularly.
As a thumb rule, lube the chain every 500 miles (800 kilometers) of distance traveled.
Third, make sure the sprocket and front sprocket area is not dirty.
Clean them once in a while so that sludge doesn’t accumulate.
Fourth and last, measure the chain slack regularly.
The slack should be in the desired free play range.
If not, adjust the chain accordingly.
The above 4 frequent diagnoses will help your motorcycle chain to run smoothly and last longer without getting loosened up.
Before you go…
Here are a few more motorcycle chain related posts for you: