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How To Fix A Broken Motorcycle Chain
In order to correctly repair the broken motorcycle chain, the first step is never to remove it directly, but to confirm the chain specification (such as 520 or 525), and to fix a matching joint and a professional chain cutting/riveting tool. The whole process is roughly as follows: first, smooth the pin shaft head of the broken chain, push it out safely with tools, and clean up the exposed inner chain links. Then apply enough grease to the pin shaft and sealing ring of the new joint, pass through the back of the chain, and press the outer chain piece in until the exposed length of the pin shaft reaches the standard. The last step is to fix: if it is a circlip type, install the closed end of the circlip toward the direction of rotation; if it is a riveting type, use tools to expand the hollow pin shaft head to the diameter specified by the manufacturer. After getting this done, don’t forget to adjust the chain tightness and wheel alignment to finish.
The following is a detailed operation guide:
Step 1: Preparation: Check The Chain Specifications And Tools
Before we do it, we have to pay attention to “precision”. Motorcycle chains are precision parts, and the consequence of mismatching parts is often that the chain breaks during driving, which is catastrophic.
Confirm the chain size: get down and look at the side plates of your existing chain. Metal is often engraved with numbers, such as 520, 525 or 530. When you go to buy a hinge, you must make sure that its pitch and width exactly correspond to this number.
Get the right joint: You have to choose one of two types:
- Clip-Style Easy to install, generally used for small displacement models;
- Rivet-Style Higher strength, permanent fixation, if you are a high-horsepower motorcycle, I strongly recommend using this.
Prepare the necessary tools: put away your vise and hammer, this job can’t be done by brute force. You must have a special chain cutting/riveting chain tool, and you must also prepare a guy who can grind metal, such as an electric grinding head or an angle grinder.
Step 2: Remove Damaged Links
Grind the pin head: Grind the pin head of the damaged chain link with an angle grinder until it is flush with the side plate. This step is to polish the edge of the “mushroom head” and greatly reduce the force required to push it out.
Plugging out the pin shaft: align the thimble of the chain cutter with the pin shaft just smoothed. Tighten the tool slowly and push the pin through completely.
Cleaning area: After the old chain links are removed, clean the exposed inner chain links thoroughly with chain cleaning agent or kerosene. If there is mud and sand here, the new O-ring seal will be useless immediately.
Step 3: Install New Joints
This step of lubrication and assembly directly determines how long the new chain can last.
Apply grease without stingy: New knuckle bags usually have small bags of grease in them. Extrude it all out and coat it thickly on the pin shaft and O-ring (or X-ring). Remember, this is the only chance in your life for these internal parts to be “full of oil.”
Insert from the rear: Put the sealing ring on and pass it through the back of the chain (the side near the engine) so that the pin shaft is facing you.
Press in the outer chain piece: cover the remaining sealing ring and put on the outer chain piece. Use the “press” function of the chain cutter to push the chain link up.
Key examination: Don’t the femoral brain to press to the end, stop and measure the after a few presses. Your goal is to make the pin shaft exposed to the same length as the chain link next door. If the pressure is too tight, the sealing ring will be squeezed and burst, and the chain link will become a stiff “dead joint”; if the pressure is too loose, the strength is not enough.
Step 4: Fixed Chain Link
How to do this step depends entirely on which style of hinge you buy.
Option A: Clip-Style
Slide the circlip into the groove of the pin with pointed-nose pliers.
Directional iron law: The closed end of the circlip must face the direction of rotation of the chain (that is, the front). If you open your mouth and scrape a branch or stone while riding, the circlip may be bounced off. You can imagine the consequences.
Option B: Rivet-Style
Switch the chain cutting tool to the “riveting” mode (usually with a special anvil and reaming needle). Align the tool with the hollow center of the pin head. Tighten the tool to flare the hollow metal outward.
Manufacturer diameter standard: this time must be on the caliper. The expanded diameter should strictly conform to the manufacturer’s instructions (such as 5.5mm to 5.8mm). If the pin shaft is expanded too hard, it will crack, and if the chain piece is not expanded enough, it will loosen. This cannot be done by feeling.
Step 5: Final Adjustment: Tightness And Alignment
Don’t rush to finish work, the geometry of the transmission system has to be back to the right. Refresh connections tend to change the effective length or tension of the chain.
Adjust the chain tightness: check the vertical swing amplitude of the chain strictly according to the owner’s manual. Adjust the rear axle adjuster until the tightness is within the standard range.
Wheel alignment: Use the scale lines on the rocker arm or a special alignment tool to ensure that the rear and front wheels are perfectly aligned. If the wheels are crooked, the crankset will wear out at a frighteningly fast rate.
Torque: In the last step, use a torque wrench to lock the rear axle nut according to the specified torque, and this work is really finished.
Author：Mark Reynolds
I’m a certified motorcycle mechanic with over 15 years of workshop experience. I specialize in drivetrain maintenance and have repaired hundreds of chains on everything from track bikes to cruisers.