All motorcycle clutches miss grabs occasionally, but if your motorcycle clutch doesn’t engage at all, it could indicate a severe issue.
And because motorcycles are dynamic machines that comprise integrated systems working together, if the clutch isn’t grabbing correctly, it may be a result of damage elsewhere in the bike.
This article lists 11 reasons why a motorcycle clutch won’t engage and how each scenario affects the various components of your motorcycle.
1. Overheating or Seized Motor
Overheating can occur between clutch components, causing them to expand, warp, or become unaligned. Once they heat up past a certain point, the engine and clutch parts can seize or fuse together, and the clutch won’t engage.
A seized engine is rare but happens on old bikes, especially those that are redlined for long periods, and bikes that are neglected.
Here’s a list of reasons why a motorcycle engine can seize up and cause the clutch to fail to engage:
- Riding with low engine oil levels.
- Inadequate storage.
- Pushing the bike’s RPMS into the redline zone.
- Riding in extreme climates, hot or cold.
- Various failures with the transmission, combustion, and engine systems.
The most common cause of overheating mentioned is riding with low or contaminated engine oil.
Your motorcycle’s gearbox components are already in close proximity and in contact with one another. So, a lack of lubrication increases that friction until they seize up or fuse, causing clutch failure.
2. Faulty Clutch Springs
When you pull on your clutch lever, the part responsible for pulling your clutch plate in and out of engagement is your clutch springs.
A motorcycle’s clutch springs furnish the room needed for shifting gears by disengaging the clutch. Your moto manufacturer designed these springs to release and snap back into place without falling out of tension.
However, the clutch springs retention can become compromised by exposure to moisture, lack of oil, or excessive use. Once the springs lose their ability to tighten themselves back into place, they can’t set the clutch plates all the way back into place.
Worn clutch springs can cause missed shifts, power loss, stall outs, and a clutch that fails to engage your flywheel.
3. Faulty Clutch Plates
Clutch plates are mounted on the friction plates inside your motorcycle’s gearbox. When you pull your clutch lever in, the plates detach from each other.
Moreover, the friction and stress of everyday use cause minor wear to the clutch plates, and the wear damages it over time.
Once the plates of your clutch becomes worn, the change to the plate’s physics prevents it from functioning correctly. And, if your clutch plates fail to detach entirely from your bike’s friction plates, your motorcycle clutch will grab, slip, and fail to engage.
4. Using the Wrong Motor Oil
Motorcycle engine oil is made in a wide assortment of grades and viscosity. They emerge from materials ranging from mineral to semi-synthetic and full synthetic, varying according to the needs of different styles of engines and motorcycles.
Your owner’s manual outlines a suggested grade and type of oil you should use.
One common cause of the failure of a motorcycle clutch to engage is using the wrong type of engine oil or running expired or contaminated oil through the transmission for an extended period.
Using the wrong type of oil changes the chemistry and mechanics of clutch operation, which can cause damage if left unchecked.
5. Clutch Cable is Out of Adjustment
The clutch cable moves the clutch by employing a harmony of tension and compression produced by the rider’s hand lever input.
The clutch cable is the piece that initiates the disengagement of your motorcycle’s clutch system from the engine. So, if the cable is too tight or too loose, the clutch won’t disengage.
- Your motorcycle’s clutch cable is the line that connects your clutch lever to your clutch.
- In order to generate the force required to disengage and engage your clutch, your clutch cable needs to be in a specific length.
- Metal cables can expand or retract in differing temperatures, so you should lubricate and inspect your motorcycle’s clutch cable regularly.
If your clutch cable has too much tension or slack, your motorcycle clutch may fail to disengage from the engine flywheel when you press your clutch lever.
6. Worn Throwout Bearing
When you pull in your clutch lever, the part of your motorcycle clutch responsible for disengaging your clutch system from the engine is called the throwout bearing.
Similarly, when you let go of the clutch lever, its throwout bearing re-engages your clutch system.
- While speed shifting accelerates the wear incurred by the throwout bearing, standard use wears down the throwout bearing on all motorcycles over time.
- You’ll experience rough shifting and missed clutch engagements until you replace a worn throwout bearing.
Moreover, failure to examine the throwout bearing during routine services is the first assuring sign that this is your culprit. An increase in resistance while shifting is the second.
Continuing to ride on a worn throwout bearing can lead to a motorcycle clutch that fails to engage.
7. Warped or Worn Out Flywheel
The flywheel is the part connecting the clutch system to the engine. While your motorcycle is in motion, so is your flywheel. Therefore, your engine flywheel endures large amounts of force during operation.
The flywheel transfers force between two robust systems, the engine, and the transmission, and is constantly subjected to friction and heat.
Eventually, the friction can cause the flywheel to wear down or even warp, especially if the bike is ridden hard or isn’t stored or maintained per the OEM’s instructions.
Once the flywheel is warped, you’ll experience increased resistance to shifting, and your motorcycle clutch may fail to engage.
The flywheel is responsible for four critical functions:
- Supplies the mass, rotation, and inertia forces that keep your motorcycle engine running.
- Engages with the starter motor to start your motorcycle
- Transfers power between your engine and the clutch system inside your transmission.
- Balances your crankshaft’s weight with its specifically engineered weight, functioning as a crankshaft counterweight.
… A warped flywheel causes damage to the various engine and clutch components it interacts with while transferring and providing force.
To learn more about how the flywheel affects the clutch, check our post on why motorcycle clutch engages late.
In case a warped flywheel is why your motorcycle’s clutch won’t engage, we suggest taking it to a pro and having it examined and replaced immediately before it causes further damage to other parts of your gearbox and engine.
8. Faulty Pressure Plates
As mentioned in a previous section, the pressure plates attach to the clutch plates. The other side of your pressure plate is bolted to the flywheel, which functions as an energy transfer between the transmission and engine.
Sitting between the flywheel and clutch plates puts the pressure plate in a position where it’s impacted by heavy force and friction coming from both sides.
Riders who routinely redline their motorcycles or ride with low oil may find that their pressure plates are incurring wear at a more rapid rate. The wear could become damaged enough to warp and fail to pressurize the clutch plate and flywheel.
The lack of pressurization hinders the power transfer between your motorcycle’s clutch and engine, and your clutch may fail to engage.
9. Leaking Hydraulic Fluid (Hydraulic Clutch Systems)
Many recent motorcycle models use a hydraulic clutch system, which uses fluid-filled lines to pressurize and engage the clutch rather than the traditional mechanical metal clutch cable.
- Hydraulic clutch lines utilize a two-part master-and-slave cylinder, which transfers the rider’s clutch lever action into the force required to engage the clutch.
- The cylinders equip seals to keep fluid in the hydraulic lines to create pressure.
- Frequent use, exposure to harsh elements, or improper bike storage can cause the cylinder seals to crack.
- Rapid temperature changes can cause the seals to change size and warp shape.
- Once compromised, these seals allow hydraulic fluid to escape.
Leaks in a hydraulic clutch line cause a change in pressure within the line. While it makes the shifting more complex, it also makes your motorcycles clutch to fail to engage completely when you press on your clutch lever.
10. Worn or Warpd Clutch Discs
The clutch disc is the gearbox component responsible for smoothing the engagement and disengagement between the clutch’s pressure plate and the engine’s flywheel.
- A motorcycle clutch disc is typically blanketed with brake pad fabric and seated between the pressure plate and the flywheel.
- The disc fabric can tatter just like the material on a brake pad from the force incurred by the two components it’s sandwiched between.
- Once the fabric is gone, the clutch disc warps and can even glaze or bind to the surrounding metal. This is the point at which it fails to smooth out the clutch/flywheel connection.
The first sign of a warped clutch disc is rough or delayed clutch engagement. If left undealt with, a worn clutch disc can make your motorcycle’s clutch difficult to engage. For better insight, read about the 11 common reasons why motorcycle clutch engages late here.
11. Improper Engine Oil Levels
As we mentioned in the first section, running your motorcycle with too little engine oil can cause severe damage, including, but not limited, to a seized engine or gearbox.
By that same token, overfilling your bike passed the spec oil fill level can over-grease the machinery and hinder the force generated and transferred by your gearbox.
Furthermore, many bikes in today’s market utilize the engine’s oil reservoir to supply oil to the clutch and gearbox. So overfilling your engine oil can result in a loss of transmission power.
It is important to note that excessive engine oil decreases the gripping power in your clutch system, reducing its transfer potential and causing your clutch to slip out of engagement.
In the light of all these, we’re sure you’d want to check out how to fix a faulty motorcycle clutch.