Dirt Bike Chain Check, Adjust and Lube, Animated

Step By Step

1. Bike on a stand

   Put the bike on a lift stand so the rear wheel hangs free. The swingarm should sit at its full drop, the way the manual measures it.

   • Lift stand

2. Clean it and look for bad links

   Brush off the dirt, then roll the wheel slowly and watch the chain. Look for stiff or kinked links, rust, missing O-rings and links that stay bent when they come off the sprocket.

   • Chain brush
   • O-ring safe cleaner

   Careful. Don’t soak an O-ring or X-ring chain in kerosene or harsh solvent. D.I.D says it can damage the seals that keep grease inside the pins.

3. Check the sprockets

   Look at the teeth on both sprockets. Teeth that lean, look like hooks or have sharp tips mean the kit is worn. Replace chain and sprockets together, since a new chain on hooked teeth wears out fast.

4. Measure the slack

   Push the bottom run of chain up and measure how far it moves at the spot your manual names. On KTM-family bikes that is at the end of the chain slider on the swingarm. Check at a few points as you roll the wheel, because chains wear unevenly.

   • Ruler

   Chain slack

   Bike	Spec	Source
   KTM / Husqvarna / GASGAS MX	58 to 61 mm	KTM 250 SX-F 2024 owner’s manual, p. 87 (on a stand, at the end of the chain slider)
   Yamaha YZ250F / YZ450F	50 to 60 mm	Yamaha YZ250F 2026 owner’s service manual, p. 60 (on a maintenance stand)

   Honda’s 2025 CRF-R owner’s manuals print no slack number; they refer you to the Competition Handbook. Check your manual for where and how to measure, because each brand measures at a different spot.

5. Check chain wear

   Wear makes the pitch longer as the pins and bushings wear. Pull the top run tight and measure across the number of rollers or links your manual names. Past the limit, replace the chain and both sprockets.

   • Tape measure

   Chain wear limit

   Bike	Spec	Source
   KTM / Husqvarna / GASGAS MX	272 mm max over 18 rollers	KTM 250 SX-F 2024 owner’s manual, p. 89 (10 to 15 kg on the top run)
   Yamaha YZ250F	242.9 mm max over 15 links	Yamaha YZ250F 2026 owner’s service manual, p. 61
   Honda CRF250R / CRF450R (race)	Replace every 3 races	Honda CRF250R 2025 owner’s manual race schedule (about 7.5 hours; RX every 2 races)
   Honda CRF450X, CRF450RL, CRF250F (trail schedules)	Inspect + lube, 300 mi	Every 300 mi (500 km) or 3 months, no replacement interval. Honda CRF250F 2025 OM, PDF p. 53; CRF450X 2025 OM, PDF p. 46; CRF450RL Off-Road Handbook, PDF p. 37

   If your manual gives no length limit, D.I.D says to replace a sealed chain at 1 percent stretch.

6. Adjust the slack

   Loosen the rear axle nut and both adjuster lock nuts. Turn the adjusters the same amount on each side until the slack is in spec, and keep the alignment marks equal left and right so the wheel stays straight.

   • Axle nut socket
   • Wrenches

   Use the chain slack from the table above.

   Careful. Too tight is worse than a little loose. A tight chain loads the countershaft seal, the wheel bearings and the swingarm, and it gets tightest when the swingarm is level.

7. Torque the axle and recheck

   Tighten the axle nut to the manual torque, then tighten the lock nuts. Measure the slack again, because tightening the axle can pull it out of spec.

   • Torque wrench

   Rear axle nut torque

   Bike	Spec	Source
   KTM / Husqvarna / GASGAS MX (M22x1.5)	80 Nm (59 lbf ft)	KTM 250 SX-F 2024 owner’s manual, p. 88

   Use the axle nut torque from your manual. It is a safety fastener.

   Shop tip. Some mechanics snug the axle nut, sit on the bike to compress the rear until the swingarm is level, and check the chain still has play there before the final torque.

8. Lube the chain

   With the chain clean and dry, spray lube onto the inside of the bottom run while you turn the wheel by hand, so it reaches the rollers and O-rings. Wipe off the extra so it doesn’t collect dirt.

   • Chain lube
   • Rag