Drive & Transmission
This guide helps with chain noises, a slipping chain or a motor that runs without moving the bike. The chain and gears that carry power to the wheel are often called the drivetrain.
Which replacement chain do I need?
Choose the chain for your CEMOTO dirt bike's wheel size:
| Front / rear wheel size | Chain type | Number of links | Replacement specification |
|---|---|---|---|
| 14-inch front / 12-inch rear (14/12) | Heavy-duty 420H | 116 links | 420H × 116L |
| 17-inch front / 14-inch rear (17/14) | Heavy-duty 420H | 124 links | 420H × 124L |
L means links. Both versions use a heavy-duty (reinforced) 420H chain, but they need different chain lengths. Check your bike's front and rear wheel sizes before ordering. If you are unsure which version you have, send your model and a photo to CEMOTO Support.
How to replace the chain — video guide
Watch this CEMOTO video to see how to replace an electric dirt bike chain.
Watch on YouTube: How to Replace an Electric Dirt Bike Chain (2 min 50 sec)
Choose the correct chain length using the table above. Follow your model's instructions for chain adjustment. If you need help, contact CEMOTO Support.
What you can check
- Stop riding and turn off the bike. Keep fingers, clothing and tools away from the chain and gears.
- Look for a chain that has come off, a broken link, rust, an obviously loose chain or damaged gear teeth.
- Note any clicking, grinding or slipping. Record a short video only if it can be done safely while stopped; do not ride to reproduce the fault.
- If the chain jumps, the wheel catches, or the motor runs without moving the bike, contact support or a qualified repairer before riding again.
Match the problem to the next step
| What happens | What to do |
|---|---|
| Chain looks dry, with no visible damage | Clean and lubricate it following your model's instructions. Keep lubricant off brakes. |
| Chain comes off or skips when accelerating | Stop riding. Have chain wear, adjustment and wheel alignment checked. |
| Broken chain or damaged gear teeth | Do not ride. Ask support to confirm replacement parts. |
| New grinding, knocking or repeated clicking | Arrange a check. Sound alone does not identify a failed part. |
| Noise when you stop pedalling on an eBike | Have a bike repairer check the chain, gears and wheel drive parts. |
| Motor runs but bike stays still | Stop using it and contact support. Do not assume the motor or one specific part has failed. |
Chain adjustment is model-specific
Chain slack means the amount the chain can move up and down. Use the measurement and checking method in your exact model's manual. A quoted 15 mm value is not a general setting for every CEMOTO bike.
Adjusting chain tension can require loosening and correctly retightening the rear axle and keeping the wheel aligned. Have a qualified repairer do this if you do not have the model instructions, tools or experience.
Cleaning and lubrication
After wet or dusty rides, let hot parts cool, remove dirt and apply a suitable chain lubricant as your model instructions describe. Wipe off excess. Check for rust, stiff links and damage. Do not turn the motor on to move the chain while cleaning it.
Wear components and warranty
The following are wear-and-tear parts and are excluded from warranty:
- Chains and sprockets
- Tensioner pulley
- Bearings and cables
- Rubber seals and grips
They are available as replacement parts at cost — see Spare Parts & Compatibility.
48V motor sprocket assembly parts
The small chain wheel on the motor shaft is called the front drive sprocket or motor sprocket. The listed 48V assembly uses a 420 / 11T sprocket (11 teeth), a 5 x 5 x 9 mm round-ended parallel key, a 6 x 22 x 3 mm flat washer, and an M6 x 12 mm external-hex flange fixing bolt, property class 12.9.
For the four part codes and their finishes, see 48V motor sprocket assembly parts in Spare Parts & Compatibility. Include your model and a clear photo when requesting replacement parts.
Related parts
CEMOTO supplies these D-series drivetrain components as spare parts:
| Part |
|---|
| D03 chains for dirt bike |
| D03 tensioner pulley |
| D03 dirt bike motor |
| D03 motor protection cover |
| D03 front / rear axle sleeve |
See Spare Parts & Compatibility for the full catalog and how to confirm compatibility with your model.