If the chain of your motorcycle isn’t adjusted to the tension specified in its owner’s manual, a slew of problems can unfold while you ride.
If it’s too loose, your motorcycle chain causes a dip in your bike’s performance, and the chain can fall off track and slap around, risking damage to engine parts and the rider.
Also, if the chain is too tight, it restricts your bike’s range of motion and causes overheating.
This article therefore explains nine things that happen if your motorcycle chain is too loose.
Table of Contents
1. Chain Hangs Too Low
If the chain of your motorcycle is too loose, it’ll start to hang too low. While a low-hanging chain is often noticeable to the eye, we suggest you measure a suspect chain to confirm if it’s out of adjustment.
While measuring your chain, we suggest you inspect it for kinks, clean it, and apply fresh grease. Take note of the following:
- Consult your owner’s manual to find the spec chain tension/slack measurement for your particular bike chain. Some bikes display the chain measurements on a sticker on the swing arm.
- With the bike’s engine off and its transmission in neutral, lean your motorcycle on its side stand.
- Locate the chain’s midway point, halfway between the front and rear sprocket, where the chain hangs the lowest.
- Follow the specific instructions in the service manual for your year mode.
- Push up on the bottom of the chain, measuring the distance between the chain as the lowest position, where it’s entirely slacked, and its highest, tightest position as you lift on the chain.
- Adjust the drive chain by loosening the jam nut three turns. You’ll likely need a torque wrench for the first crank.
- At the rate of just one-quarter turn per twist, adjust each side of the swing arm until the chain is at spec tension, measuring and adjusting until the chain is in the manual-prescribed hanging distance.
- Use your torque wrench to tighten the jam nut back to the specified torque outlined in the owner’s manual.
2. Chain Tugs and Jerks in Low RPMs
Another thing that happens when your motorcycle’s chain is too loose is a tugging and jerking chain, which causes a noticeable resistance to your bike’s motion.
Since motorcycle chains are most slacked in lower gears, this heavy chain tug sensation will be most noticeable at low RPMs. To easily detect the situation, check the symptoms that indicate a motorcycle chain is too loose here.
In some cases, the jerking and tugging chain sensation is enough to make riders think their transmissions are faulty when it’s simply the resistance physics caused by too much free play.
In addition to routine measurements and adjustments described in the previous section, motorcycle chains require consistent upkeep, inspections, cleaning, and lubrication in order to hold their spec tension.
We suggest you inspect your chain’s tension every 500 miles to prevent chain-tug interference on your bike’s momentum while you ride.
3. Reduced Engine Performance and Fuel Efficiency
One issue that happens early on as a result of a loose motorcycle chain is the visual loss of fuel efficiency and engine performance.
Your motorcycle chain transmits power from the engine to the rear wheel. As it jerks, tugs, shakes, and vibrates, the chain sheds much energy before reaching its destination.
Furthermore, the vibration generated by a loose motorcycle chain can have a negative impact on engine combustion. If the vibrations are intense enough, they can alter your engine tuning via incomplete combustion and shifts in your air: fuel ratio.
An improper air-fuel ratio increases your bike’s emissions and decreases its fuel efficiency.
- The heat generated by the friction of a loose lashing chain emits into your engine, which can interfere with the effectiveness of your oil’s lubrication.
- An increase in engine heat forces your bike’s various motor parts to work harder, increasing the wear rate.
- If your motorcycle chain is loose, you may realize you’re going through oil and conducting maintenance more often to keep your bike running like usual.
Finally, a loose motorcycle chain interfered with your bike’s shifting process, leading to false neutrals and missed shifts. These can thrust you into inefficient gear for your current riding speed and conditions.
4. Loose Chain Causes Sprocket Damage
A loose motorcycle chain can damage its own sprockets, rollers, and seals at an accelerated rate due to jerking, lashing and overheating caused by increased friction.
It also jumps and skips over sprocket teeth, causing interference to your bike’s performance. It also risks the loss of rider control, and damage to the sprocket teeth.
Suppose the chain is loose enough to damage itself and its rollers and sprockets. Then, it starts risking jumping off track and slapping against its chain guard and swing arm. This causes the more severe damage explained in the subsequent sections.
The fact is, if the chain snags against the sprocket and breaks, it can cause a collision. This is further explained in the last section of this article.
5. Chain Jumps Off Track
If your motorcycle chain is loose enough to slap around and you’ve ignored the previous symptoms, it’s only a matter of time before the chain jumps off its snags and sprockets altogether.
At its spec tension, a chain evenly transfers energy from your transition to the rear wheel. Conversely, a motorcycle chain that’s too loose flails around spontaneously, discharging its energy.
Eventually, the lashing chain can build up enough force to jump off its track, damaging other parts in its surroundings and risking hurting the rider.
Therefore, inspecting and servicing your chain every 500 miles and catching a loose chain at the earliest symptoms can fix the issue before the chain develops enough slack to jump off its cogs.
6. Chain Slaps Against Surrounding Components
If your motorcycle chain is too loose, you may experience a hazardous scenario called chain slap or chain lash.
As the descriptive phrase describes, a chain slap is when a motorcycle chain is so loose that it can gain enough momentum and force to lash around and slap against the surrounding metal components.
You’ll first recognize a chain lash as a startling clanging sound most noticeable at acceleration and deceleration of the throttle.
A chain that’s loose enough to throw itself around gets looser and looser as it whips back and forth and heats up. Eventually, the chain gets so loose that it slaps against the chain guard.
In extreme situations, the chain can even lash against the bike’s swing arm and cause damage, which we’ll cover in the next section.
Furthermore, chain slap causes damage to the chain itself, accelerating the wear on the chain rollers and the chain’s internal rubber seals.
If your chain becomes loose enough to lash around, the lashing motion causes wavering power transmission to the wheels. This causes a jerky motion in your motorcycle, especially while accelerating.
7. Chain Damages Motorcycle Swing Arm
A loose motorcycle chain, at the point of clapping and lashing around, can eventually loosen itself enough to graduate from damaging your chain guard to hitting against your swing arm.
A lashing loose chain chips away at the metal swing arm as it slaps against it. If left unchecked, the swing arm incurs so much damage from the chain slaps that its integrity and stability are compromised.
Furthermore, a lashing chain can damage the seal equipped to keep moisture out of your swing arm and grease inside it.
Motorcycle swing arms have rubber rings fitted around the point where the swing arm connects to your motorcycle’s frame. The rubber seals keep the bearing grease inside the swing arm to keep water and dirt out.
Because your swing arm bearings are responsible for gliding the swing arm’s pivot smoothly, a loose and lashing motorcycle chain can have a negative impact on the swing arm’s movement and suspension travel.
Replacing your swing arm bearings is a technical procedure requiring specialty tools. We suggest you tighten your chain at the first sign of slap and damage to your chain guard before it leans enough to thrash against the swing arm, damaging its metal, seals, and bearings.
Mind you, it is important to ensure the chain of the motorcycle is not too tight.
8. Accelerated Transmission Wear
A loose motorcycle chain accelerates the wear and tear incurred by your motorcycle’s transition system.
A loose chain adds unnecessary stress on the engine and transmission components it interacts with. It does this both directly and indirectly by adding resistance and changing the physics of the whole operation.
Additionally, a loose motorcycle chain induces an increase in vibration, which affects transmission performance and hinders its smooth operation.
An overtly slacked motorcycle chain also generates more friction and heat, tarnishing the chain grease and compromising the efficient performance of your various gearbox components.
Finally, as mentioned earlier, a loose motorcycle chain can interfere with your motorcycle’s shifting abilities. This triggers rampant false neutrals and missed shifts, both of which cause stress on your transmission system.
9. Broken Motocycle Chain, Locked Wheels, and Collision
If left unresolved after all the abovementioned symptoms, a loose motorcycle chain can brake, causing your wheels to lock up and risking a collision.
As discussed earlier, a loose motorcycle chain can slip over the sprockets and get jammed between the rear sprocket and swing arm. This could lock up the bike’s rear wheel and cause it to skid.
A loose chain can snap and wrap itself around the wheel or get stuck in the brake caliper, causing real-wheel lock-up and loss of rider control.
In the process of braking, a loose motorcycle chain can also shoot behind you and into another vehicle. While it could cause a damage and personal injury, it could also lead one or both of the automobiles into a crash.
If the chain of your motorcycle brakes when you’re in traffic or when riding technical roads at high speeds, you might not have the opportunity to react in time to prevent injury to yourself or others.
Besides, you might also not be able to prevent damage to your bike or surrounding property.
This is why we suggest you inspect, clean, and lubricate your chain every 500 miles. Ensure it’s slacked to the spec outlined in the owner’s manual associated with your motorcycle’s make and year model.