How Tight Should A Motorcycle Chain Be?

how much slack should a motorcycle chain have?

In the lower part of the chain, when the motorcycle is parked on the side bracket or the middle support, the best tightness of the motorcycle chain is when the distance you can push the chain up and down with your fingers is about 20mm-40mm, but it must be noted that the standard of motorcycle chain slack of each motorcycle is different, which is only a general reference range.

How to accurately adjust the tightness of motorcycle chain

As a technician, I suggest you use a more professional and accurate method to adjust the tightness of the chain.

Recommended Tools

• Chain slack tool: This is the most ideal tool, many brands have production, it allows you to quickly and accurately measure the free travel of the chain.
• Vernier calipers: If you don’t have a special tool on hand, vernier calipers can also come in handy. Although not as convenient as special tools, but the accuracy is sufficient.

How to adjust the chain on a motorcycle?

Preparation: Park the motorcycle on a flat ground. It is best to use the parking frame to lift the rear wheel so that it can turn freely.

Find the tightest point: this is crucial! Slowly turn the rear wheel while feeling the tightness of the chain with your hands. At a certain position, you will find that the up and down free travel of the chain is the smallest, which is the tightest point.

Measuring motorcycle chain slack:

• Chain Slack Tool: According to the tool instructions, place it in the middle of the chain and measure the distance of shaking up and down.
• Vernier caliper: In the middle of the chain, push the chain up to the top by hand, and measure the distance from a reference point to the rocker arm with a caliper; then press the chain down to the lowest point, and measure the distance from the same reference point to the rocker arm again. The difference between the two is the free stroke.

Adjustments:

Loosen the rear axle nuts.

Slowly adjust the tightness of the chain by adjusting the chain adjustment bolt at the end of the rocker arm. Turn only a little at a time and measure again.

Refer to the vehicle manual: The chain slack of each motorcycle has specific requirements, usually between 20mm and 35mm. Be sure to consult your vehicle’s owner’s manual and adjust to the manufacturer’s recommended values. This is not something that can be done by feeling.

Review: After adjustment, tighten the rear axle nut (pay attention to torque!), Then turn the rear wheel again and measure the tightness of the chain at multiple points to ensure that it meets the requirements in all positions.

Common misconceptions

• According to the hand feeling estimation: many novices like to touch the 1 with their hands, shake 1 shake, think it is almost enough. This method is so wrong that neither the naked eye nor the hand can provide sufficient accuracy.
• Ignore the tightest point: This is what I have repeatedly emphasized. If you adjust in the loosest part of the chain, it is tantamount to burying hidden dangers.
• Don’t check the manual: The parameters of each car are different. Blindly adjusting according to the “general standards” on the Internet or in other populations is likely to cause problems.

How important is chain tightness?

I dare say that the tightness of the chain is one of the core factors affecting your motorcycle riding experience and life.

Safety hazard

• The motorcycle chain too tight: It will increase the load on the chain, chainring, front and rear wheel bearings and gearbox output shaft, causing premature wear of these components. What’s more serious is that it will limit the normal operation of the rear suspension. On bumpy roads, the free travel of the rear wheels may be insufficient, resulting in reduced handling and even breakage in extreme cases! I have seen cases where the rear wheel bearings are locked because the chain is too tight, which is a great threat to life.
• The motorcycle chain too loose: The chain is easy to fall off, especially when accelerating or decelerating, which will instantly cause power interruption and even jam the rear wheel, causing serious traffic accidents. At the same time, a chain that is too loose will also produce unnecessary jitter and noise during driving, which will accelerate the wear of the chain and the guide block.

Performance impact and lifetime consumption

• The motorcycle chain too tight: it will increase the transmission resistance, resulting in power loss and fuel consumption. The engine needs to output more power to overcome this additional resistance.
• The motorcycle chain too loose: The power transmission efficiency is reduced, and you will feel that the vehicle acceleration is not linear enough and the power response is slow. Long-term looseness will also cause uneven wear of the chain, and ultimately shorten the life of the chain and the toothed disc.

Recommendations for chain maintenance and daily inspection

Cleaning motorcycle chain and lubing motorcycle chain

This is the most basic! Cleaning can use professional chain cleaner and brush, and then use chain oil for lubrication. Good lubrication can greatly extend the life of the chain, reduce friction and noise.

If you want to know when to clean and lubricate, you can read XXX’s blog

Periodic inspection

• Visual inspection: Before each ride, take a minute to see if the chain shows signs of rust, wear, or breakage.
• Check the tightness: check the tightness of the chain regularly (for example, every 1000 kilometers) to ensure that it is always within the normal range.
• Check O-rings/X-rings: These rubber seals are the key to maintaining internal lubrication of the chain. If it is found to be damaged or falling off, it means that the chain life is approaching.
• Check the wear of the toothed disc: observe the tooth shape of the front and rear toothed discs. If the tooth tip becomes as sharp as a shark fin, it means that the toothed disc has been seriously worn and needs to be replaced. Usually, the chain and the toothed disc are recommended to be replaced together.

Technician Advice

I have been in this business for decades and have witnessed countless vehicle problems, many of which stem from the neglect of small details. As the core component of the motorcycle transmission system, the state of the chain is directly related to your riding safety and vehicle performance. Don’t wait for problems to pay attention, daily inspection and maintenance is king. If you are not sure how to operate, or feel that it is difficult to do it yourself, please be sure to hand over the car to a professional technician. After all, safety first!