1997-2001 Honda CR250 – Sprocket & Drive Chain Maintenance

How To Service The Sprockets & Drive Chain On Your 1997 – 2001 Honda CR250

1997 - 2001 Honda CR250 -Sprocket & Chain ServiceTry to always change your sprockets and chain as a set. Using new parts with old parts will shorten the service life of both!

The Tools You Will Need To Change Your Sprockets & Chain Are:

  • PB Blaster
  • Rubber Mallet
  • Large Pliers
  • Stiff Brush
  • Flat Head Screwdriver
  • 8mm Socket
  • 12mm Socket
  • 13mm Box Wrench
  • Torque Wrench
  • Pick
  • 6mm Allen Wrench
  • Tiny Flathead Screwdriver
  • Bucket O’ Grease
  • Carb Cleaner

The only specialty tool you will need is a chain breaker.  Your master link pins may not be a press fit, but they probably are, and you will need the right tool.


The parts you will need are a new O-ring, part number: 91201-ML3-873 for the countershaft, and possibly a new set of sprockets and a chain, but you’ll find that out later.

You Can Get Parts And Tools Through Our Partner Links HERE!

Related: 1997-2001 Honda CR250 Remove & Install Rear Wheel

Start with your bike on a stand and your transmission in 1st gear.

Click Here For Drive Chain Specifications

Sprocket & Drive Chain Removal

(Click to Enlarge)
Front Sprocket Removal
Remove the front sprocket guard and backing plate.Remove Sprocket Guard And Bracket
If you try to turn the bolt, you will turn the engine, so use a ratchet strap to hold down the rear brake. Be Careful!
With the rear brake engaged, loosen and remove the front sprocket bolt, washer, and sprocket from the countershaft.Loosen Front Sprocket BoltRemove Front Sprocket Bolt
Carefully remove the collar from the countershaft.Remove Countershaft Collar
Be careful around the countershaft seal, if you are using a screwdriver to pry the collar out, be very patient! Be Careful!
Rear Sprocket Removal
Lay your rear wheel on a towel with the brake side down.Place Rear Wheel Brake Side Down On A Towel
Coat the sprocket bolts with PB blaster, then flip your wheel and spray the sprocket nuts.Spray Rear Sprocket Bolts With PB BlasterSpray Rear Sprocket Nuts With PB Blaster
After the PB does its job, loosen and remove the rear sprocket hardware.Remove Rear Sprocket Hardware
Chain Removal
Locate the master link, then rotate the chain, so it sits on top of the swing arm.Locate Master Link
Lay your left forearm on the chain, with your screwdriver facing the front of the bike.Place Forearm On Chain
Align the blade of your screwdriver with the open end of the spring clip.Remove Spring Clip With Mallet
If it was installed correctly, the open end should be facing the back of your bike.Be Careful!
Give the butt of the screwdriver a tap with your rubber mallet and the spring should pop off the pins.Align Screwdriver With Open End Of Spring Clip
Align your chain breaker, so it pushes the pins toward the bike, and remove the pinsBreak Drive Chain With Chain Breaker
This works for both roller and O-ring chains.

Sprocket & Drive Chain Inspection

Before you bother cleaning the sprockets and chain, check to see if they are worth keeping.  
Check both sprockets for excessive tooth wear.
Check the back sprocket for signs of uneven wear and straightness.
There is a wear spot on the rear sprocket, but it’s most likely something I hit because the sprocket is still straight and worn evenly.
Chain Inspection
Lay your chain flat and pull it straight and measure the span of 17 pins.
The span between the 1st and 17th pin should not exceed 10 and 1/8th inch.Be Careful!
Check the pins and side plates for damage or signs of uneven wear.
This chain and sprocket set are still good, so it looks like I saved myself about $100 today!Green Check Mark
Clean & Inspect
Clean everything with carburetor cleaner, then rinse with warm water.
Hang your chain, and wrap everything else in a towel to dry.
Clean your countershaft using carb cleaner, a towel, and a tiny screwdriver.
Clean the splines as best as you can.Be Careful!
Once the countershaft is thoroughly wiped down, remove the O-ring, and throw it away.
Sprocket & Drive Chain Installation
Rear Sprocket Installation
Start your installation with the rear sprocket.Install Hardware On Rear Sprocket
Install the sprocket hardware hand tight, then torque the rear sprocket bolts in a criss-cross pattern.

  • Torque to 24 ft-lbs
Torque Rear Sprocket Bolts
Front Sprocket Installation
Install the new o-ring onto the countershaft.New O-Ring For Countershaft Part Number 91201-ML3-873 Install New Countershaft O-ring
Grease and install the collar with the groove facing in.Grease And Install Countershaft Collar
Mount the front sprocket with the flat side facing out.Install Front Sprocket Flat Side Out
Install the bolt and washer with the outside markings facing out.Install Sprocket Bolt And Washer
Chain Installation
Run your chain through the guides, so the ends meet on top of the swingarm.Run Chain Through Guides
The easiest way I have found for installing an o-ring master link is to drive the pins through the inside plate first.Be Careful!
Place the o-rings on the pins, then slide the pins through the holes.Install Inside Plate Of Master Link
Then take the inside of the chain breaker to press the outside plate onto the pins.Press Outside Master Link Onto Pins
Once the pins are pressed in, install the spring clip.
Align the spring clip, with the closed end facing forward.Place Spring Clip On Pins
With your screwdriver, pry the open end halfway onto the link.Pry Spring Clip Onto Pins
Then push the clip the rest of the way.Finish Installing Spring Clip
Install your chain on both sprockets.Install Drive Chain On Front And Rear Sprockets
Apply the rear brake, and torque the sprocket bolt.

  • Torque to 20 ft-lbs
Torque Front Sprocket Bolt To 20 ft-lbs
Reinstall the sprocket guard and bracket.

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