I picked up my new to me CR250 and was ready to rip through the gears without the clutch. Then I stopped and questioned whether doing this was safe for my transmission. Here is what I found out.
Can you shift a dirt bike without using the clutch? Yes, you can shift a dirt bike without the clutch, moving up and down in the gears. There is much debate about whether it is harmful. Shifting the dirt bike up (from first to second to third ect) will be ok. Shifting in specific ways may cause damage to your transmission.
It may confuse you about why damage occurs by shifting down but not up. You need to better understand how the dirt bike transmission and clutch work and the advances that will make this debate irrelevant moving into the future.
What is the clutch and how does it work?
The clutch is a mechanism that connects the engine to the transmission. When engaged the clutch allows power from the engine to transfer to the transmission.
The rider disengages the clutch using a lever on the left-hand side of the handlebar. To disengage the clutch, the rider pulls in the lever. To engage the clutch again, the rider lets out on the clutch lever.
If you plan on not using your clutch to shift your dirt bike, 90% of the clutch action will come from starting and stopping the dirt bike. You still use the clutch in these situations to keep the engine going. I am sure as a new rider you let out on the clutch lever to quickly and killed the dirt bike or forgot to pull the lever while coming to a stop. The result? The dirt bike stops running.
Clutch Pack
The actual clutch is a series of friction and smooth plates that get smashed together engaging the engine to the transmission. When you pull the lever we were just talking about, the plates create a gap stopping the power delivery from the engine. The engine still runs bit it is not transferring power to the transmission.
You can find the clutch in a dirt bike by looking for the larger round area of the engine cases.
INSERT PHOTO OF THE CLUTCH ARE OF ON THE CASES
Understanding The Dirt Bike Transmission Shifting
You may ask, “Why do I need to understand my dirt bike transmission?” These are different transmissions from what you have in your car and different from the standard manual transmission in a car too.
Most of us drive a car with an automatic transmissions and the car shifts gears on its own both moving up through the gears while speeding up and with down shifting as it slows down. The driver has no worry about matching RPMs to the speed of the vehicle for gear selection.
Manual Transmission
With a manual transmission, the driver needs to worry about matching the speed of the car to the car and engine RPM. The driver can move into whatever gear she wants except reverse.
I have moved from first, to third, to fifth gear before. Again you need to be mindful of matching car speed, engine RPM, and gear selection.
To make this process smooth, you need to use a clutch.
Dirt Bike Transmission
Dirt bikes have a constant-mesh transmission. This means the gears are always moving and rotating freely around a shaft. The gears “shift” and lock into place by a sliding collar. Some riders refer to this as a dog clutch.
Since the gears rotate around the same shaft, the gears can be engaged in a sequential manner. Recall from the manual transmission description above a driver can move from first gear to third and then fifth gear.
On a dirt bike, to get to fourth gear, you must first shift into first then second gear, next into third and last into fourth. This is the definition of a sequential transmission.
When transmissions are sequential, it is easier to shift without the clutch and not worry as much about tearing up the transmission or over revving the engine.
Shifting Techniques Without The Clutch
You have a few options to shift without using the clutch.
Shifting Your Dirt Bike Without The Clutch And Wide Open Throttle
Many racers keep the throttle wide open as much as they can and keep running the motorcycle through gears. This technique will exert the most stress on your transmission.
The wide open throttle method allows for quicker shifts while keeping the dirt bike at the optimum point in the power band. Under normal dirt bike riding at a slower pace, the RPMs move up and down out of the power band because of rolling on and off of the throttle while shifting.
As I just mentioned, this shift technique exerts the most stress on the transmission because of the forced maneuver of jamming the transmission into the next gear. This will not be as hard on the clutch since it stays engaged. Effectively you are making the transmission match with the engine RPMs
When you shift with the clutch, it allows the engine RPMs to match the transmission. Some gear heads would not agree saying the transmission will change gears. While this is true, the RPMs will move out of the power band preventing added stress on the gearbox. Here, the engine is moving further than the transmission.
Racers use the wide open throttle because they know they will rebuild the transmission many times with new parts. They only use this going up through the gears. When downshifting they will let off the throttle and just down shift. The engine in this case will act as a brake. As a rider you’ll notice the back tire chalking the ground and dragging behind you.
As a leisure rider, you need to know of the added stress you put on your dirt bike. For this reason, I do not recommend using the wide open throttle method often. Ok, maybe when you’re racing with your buddies in the backyard now and then.
Downshifting A Dirt Bike Without the Clutch
You may have picked up on the downshifting technique without the clutch under the Shifting With A Wide Open Throttle section. If not here is the basic technique:
When you need to slow down and want to skip using the brake, try downshifting the transmission into a lower gear. If you downshift from a higher speed, do not be surprised if you downshift through a few gears. For example, say you are coming to the end of a long straight away in fourth gear and need to take the corner in second gear or first. You will downshift without the clutch through two or three gears.
Why would I downshift without my clutch?
First you would normally do this when you want to go fast around the track. If you are riding for leisure, you will probably use the clutch.
When done correctly, not using the clutch puts the engine RPMs closer to the power band for a fast acceleration away from the corner.
Avoid The Clutch And Rolling The Throttle
The last technique would have you ride as if you were using the clutch by rolling the throttle on right after you shift into a new gear and off as you get ready to enter a new gear.
There is less stress on the transmission than the wide open throttle method. This will take a little practice if you are not used to the clutch.
Never Worry About The Dirt Bike Clutch By Using New Technology
You read this section correctly. There is the technology out there that allows you to avoid the clutch or allows you have it as a helper. I will give you an overview of what they are. Adventure Rider Radio has a whole podcast about this topic and will be the best resource for the technical knowledge.
The Double Clutch
Some manufactures installed these into youth ATVs some time ago. It did not take off again until recently.
Basically, you have two clutches working by hydraulic pressure and allows you to have a smooth shift almost like your car.
Rekluse Clutch
The Rekluse system uses many of the same components in your existing system but with different springs and smaller hardware. From what I can gather, you improve your riding because this takes much of the human error out of riding with knowing how much clutch to use and when to use the clutch.
Related Questions:
Do all dirt bikes have clutches? No, there many models that have semi automatic drive systems where you still shift but do not use a traditional clutch to move from one gear to the next. There still other motorcycles that do not have a clutch or gear shifter.
Do supercross racers shift gears? They shift gears and perhaps the worst as not using the clutch. They avoid the clutch to allow for quicker shifts. Their motorcycles are rebuilt frequently so changing worn parts will not be a problem or concern for the racer.