The specification—and exactly which bike it covers
For the 2020 U.S. Honda CRF250F, the owner’s manual specifies 30–40 mm (1 3/16–1 9/16 inches) of drive-chain slack. Check with the engine off, transmission in neutral and motorcycle on its side stand. Measure the lower run midway between the sprockets. Verify your own model-year manual before applying this number; a CRF250R, CRF300F or another motorcycle is a different application. [1]
Measure total up-and-down movement
The slack figure is the chain’s vertical travel at the specified point, not simply the gap between the chain and swingarm. Motion Pro’s tool instructions distinguish total slack from chain-to-swingarm measurements. Read the method before choosing a scale on a measuring tool. Take the measurement deliberately so you can reproduce it after any adjustment. [2]
A tool for this step: Motion Pro Slack Setter Pro (Amazon paid link). Use the manual’s bike position, measuring point and specified method. Check tool clearance and use the appropriate scale; the tool does not establish the CRF250F specification. We may earn a commission from qualifying purchases.
Check more than one chain position
Honda calls for checking at several positions. With the engine stopped, carefully roll the motorcycle by hand to reposition the chain and repeat the check. Keep fingers clear of sprockets. Uneven readings, binding or damaged links deserve inspection; repeatedly changing an adjuster does not repair a damaged chain. See the drive-chain section beginning on printed page 98 of the linked manual. [1]
Before touching the adjusters
Record the readings first. If an adjustment is needed, follow the complete model-year procedure for axle loosening, wheel alignment, adjusters and final tightening. This article is a checking guide, so it does not substitute a generic torque number for the specified fasteners. Motion Pro also instructs users to recheck slack after the axle is tightened. A loose-axle reading is not the final check. [2]
A separate alignment aid: Motion Pro Chain Alignment Tool (Amazon paid link). This tool has a different job from the slack gauge: it helps check sprocket-to-chain alignment. Confirm clearance and follow the motorcycle’s complete adjustment procedure. Recheck slack afterward as instructed. We may earn a commission from qualifying purchases.
Cleaning advice depends on the chain
Identify the fitted chain before choosing chemicals. D.I.D’s dedicated maintenance guidance calls for cleaner and lubricant compatible with sealed chains and warns against kerosene, gasoline, wire brushes and steam cleaning. If a general guide and the chain maker disagree, use the instructions for the actual chain rather than mixing procedures from different products. [3]
A lubricant option to check: Maxima Chain Wax · 74920 / 13.5 oz net weight (Amazon paid link). This is Maxima 74920 Chain Wax. Maxima identifies it for sealed chains, but confirm the requirements of the chain actually fitted. It is lubricant, not cleaner, and does not replace a slack check or repair damaged links. Follow the label and chain instructions with the engine off; protect tires and brakes from spray. We may earn a commission from qualifying purchases.
Keep a record you can use again
Write the manual edition, measuring position and readings in your service log. That turns the next check into a comparison instead of a fresh guess. Inspect before a ride rather than discovering a problem while loading the bike. If the readings vary sharply around the chain, have the chain and sprockets assessed together before treating the problem as routine adjustment.
Related reading: The CRF250F-to-CRF300F model transition.
Measure, check alignment and choose compatible chain care
The measuring tool, sprocket-alignment aid and lubricant have separate jobs. Find the actual chain’s care requirements before choosing a lubricant, and use your model-year motorcycle manual for slack and adjustment. None of these products establishes the specification or repairs a worn chain.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. These Amazon links are paid links. How our links work.
Motion Pro Slack Setter Pro
A compact measuring aid with separate scales for chain slack and chain-to-swingarm distance. Use the scale that matches the motorcycle manual’s measuring method.
Before you buy: Follow the exact bike manual for position, measuring point and specification. Motion Pro excludes gull-wing swingarms. This tool does not replace a torque wrench or confirm fitment for every bike.
View on Amazon (paid link) — Motion Pro Slack Setter Pro, 08-0674Manufacturer details · 08-0674Motion Pro Chain Alignment Tool
Clamps to the rear sprocket and uses an indicator rod to help check the chain’s alignment with the sprocket.
Before you buy: Confirm sprocket clearance and the tool instructions. This is an alignment aid; it does not measure slack, verify complete wheel alignment or replace the bike’s adjustment and torque procedure.
View on Amazon (paid link) — Motion Pro Chain Alignment Tool, 08-0048Manufacturer details · 08-0048Maxima Chain Wax · 74920 / 13.5 oz net weight
The inspected Amazon listing is the 74920 motorcycle Chain Wax aerosol. Maxima identifies this chain lubricant for sealed-chain types including O-, X- and Z-ring.
Before you buy: Identify the actual fitted chain and confirm its lubricant requirements before choosing. Check 74920 and the can’s net weight; Amazon’s fluid-ounce selector is not the can label. Follow the chain maker and aerosol label, including handling and settling instructions. Lubricant does not repair worn links or correct slack or alignment. Keep spray off tires and brakes; work with the engine off.
View on Amazon (paid link) — Maxima Chain Wax · 74920 / 13.5 oz net weight, 74920Manufacturer details · 74920The measuring and alignment tools complement different parts of the job; they are not interchangeable checks. Confirm clearance, the applicable model-year manual and current tool instructions. No new hands-on testing or universal torque/slack setting is supplied.
Sources & technical information
- 2020 Honda CRF250F U.S. owner’s manual.
- Motion Pro: SlackSetter Pro instructions.
- D.I.D: drive-chain maintenance guidance.
Sources checked Oct 22, 2026 (UTC). Fitment, specifications and procedures vary; confirm the current manufacturer instructions for your exact bike and component.