Forget first gear. I get the clunk sound while shifting to any gear. And surprisingly, there is no clunk sometimes when I shift gears. It’s smooth one time and it’s hard clunks the other.
So, motorcycle clunk into first gear, why and is it serious? A clunking noise when you shift to first gear is not a problem. Most motorcycles have it. The clunk is because the dog clutch is engaging with the gear in the gear transmission.
If, on the other hand, the clunk is too loud and there are some noticeable jerks, you should dig a little deeper. And check if everything is working fine.
Let’s look into the clunk a bit more then.
Is a clunk into first gear normal?
A small clunking sound when shifting to first gear is normal in a motorcycle.
In most motorcycles, there will be some kind of noise while shifting gears. The clunk is more audible when shifting from neutral to first gear. Especially when you are starting the motorcycle.
There is no need to worry at all. These clunking sounds are pretty common across motorcycle models.
In fact, many speculate that this clunk is by design. Manufacturers know about the clunk but do not bother addressing it.
While I am not sure how true is this, there definitely is no big deal with the clunking noise while shifting gears.
In fact, many motorcycle riders like that sound. It is soothing and satisfactory for them. Anything is ASMR nowadays, I kid you not!
What causes this clunking sound?
Small clunking sounds are normal in most motorcycles. Whenever you change the gear, you can hear a small audible sound most of the time.
This small clunking noise is mainly because of gear transmission.
Motorcycles use what is called a constant mesh gear transmission.
Without getting too technical, let me explain constant mesh gear transmission in brief.
There are two kinds of gear on this transmission.
The first is free-wheeling gears. These are the gears that are rotating freely on the shaft. There will be 5 or 6 of them. These are the gears that need to be engaged depending on which gear the motorcycle is shifting to.
The second type is dogs. Yes, dogs. Also called dog clutches. The dogs can slide side to side on the shaft, and engage with the freewheeling gears.
Every time you change the gear, the dog disengages from one gear and engages with another free-wheeling gear (need not be the same dog).
When the dog engages with the freewheeling gear for transmission, that’s when you hear a clunking noise.
Still confused? Here is a video that explains in detail how gear transmission in a motorcycle works.
The clunk is more audible when shifting from neutral to the first gear, especially when starting the motorcycle. This increased clunk is because the output shaft which was not rotating before gets engaged. And then starts rotating once the dog engages with the first gear.
When should the clunk concern you?
Now, we know the clunk is not a big deal. There is no need to worry about it.
But, if there is a loud clunk whenever you are shifting gears, and a jerk as well, then you need to check for the cause.
While a loud clunk is not necessarily a concern, too loud a clunking noise can mean something is wrong.
Plus a jerk. That would certainly indicate some problems with your motorcycle.
So if the clunk is too loud and there is a noticeable jerk when you are shifting gears, then you should inspect your motorcycle once.
Reasons for loud clunk on gear shifts
If there is a loud clunk as well as some jerk while shifting gears, here are the possible reasons:
1. Low-quality oil
Low oil levels or poor quality engine oil is one main reason for the loud clunking noise during gear shifts.
Check the oil level first. It should not be low.
Next, check the oil quality. Look into the color, smell, and stickiness of the engine oil.
A good quality oil should be brown or lighter in color. The oil should not have a burnt smell. And it should not be sticky.
Now, even if the oil level is right and is of good quality, it might not be the right fit sometimes. Especially if the viscosity is too high and the engine is cold.
If the loud clunk is in cold conditions or during the winter, then the engine oil grade might have something to do with it.
Make sure you are using a multigrade oil with a good winter grade. Here is a guide on engine oil grades to help you choose the oil.
2. Clutch cable slack is not right
Whenever you are changing the gear, disengaging the clutch is important.
Only when you pull in the clutch lever, you will disengage the clutch. If the clutch cable slack is not right, there won’t be proper disengaging.
If the slack is too tight, i.e., lower slack than the required specifications, pulling the clutch wire completely will not be enough to fully release the clutch plates.
Similarly, if the slack is too high, i.e., higher than the required specifications, the clutch can slip even when you have fully released the lever.
Usually too tight is the problem for loud clunking noise. So check the clutch slack and adjust the free play.
3. Warped clutch plates
Warped or burnt clutch plates not only cause clunking but also lead to hard gear shifting.
Shifting gears won’t be smooth. You will start noticing pickup problems as well. The motorcycle will not pick up speed even if you accelerate the throttle.
So, warped or burnt clutch plates can be another reason for loud clunking noise while gear shifting.
Solutions and Preventive measures
If there is too much clunking noise and jerks, here are the things you can address to eliminate the issue:
- Change the engine oil: Low oil levels are a problem. Low quality as well. Engine oil deteriorates over time. You have to change the oil regularly. If you haven’t, then time to add fresh oil to your motorcycle.
- Use multigrade oil suitable for cold conditions: If you live in cold climates, use suitable engine oil. The oil should work fine in winter as well. Go for a multigrade oil with a good winter grade.
- Check for clutch plate burning and replace if necessary: If the clutch plate is already burnt or warped, you must replace it. There is no other option. Ensure proper clutch usage while changing gears next time.
- Adjust the clutch free play: Adjust the clutch by giving it a proper slack. The cable should have some free play to operate and at the same time, the slack should not be too much. Try adjusting for 2mm to 3mm. Feel it. Then repeat accordingly.
Helpful read: Tips to shift gears easily
Final thoughts
First things first. A clunking noise when you shift to first gear is not a problem. Most motorcycles have it.
Only when the clunking noise is too loud and there is some jerk while you gear shift, you should worry. And start looking for the reasons and solutions listed above.