1997-2001 Honda CR250 – Sprocket & Drive Chain Maintenance

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1997 - 2001 Honda CR250 -Sprocket & Chain Service

How To Service The Sprockets & Drive Chain On Your 97-01 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

  • 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
  • Carburetor 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.

New Chain And Sprocket Parts

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.

Pre-Service Notes

  • Start with your bike on a stand and your transmission in 1st gear.
  • I recommend opening the Service & Torque Specs in a new tab for easy reference.
  • If you need parts and tools, make sure to buy them here!
  • Pictures with captions are after the steps below.
  • If you need any help don’t hesitate to ask!

Sprocket & Drive Chain Removal

Front/Drive Sprocket Removal

    1. Remove the front sprocket guard and backing plate.
    2. If you try to turn the bolt, you will turn the engine, so use a ratchet strap to hold down the rear brake.
    3. With the rear brake engaged, loosen and remove the front sprocket bolt, washer, and sprocket from the countershaft.
    4. With the rear brake engaged, loosen and remove the front sprocket bolt, washer, and sprocket from the countershaft.
    5. Carefully remove the collar from the countershaft.
    6. Be careful around the countershaft seal, if you are using a screwdriver to pry the collar out, be very patient!
Remove the front sprocket guard and backing plate.
Remove the front sprocket guard and backing plate.
If you try to turn the bolt, you will turn the engine, so use a ratchet strap to hold down the rear brake.
If you try to turn the bolt, you will turn the engine, so use a ratchet strap to hold down the rear brake.
With the rear brake engaged, loosen and remove the front sprocket bolt, washer, and sprocket from the countershaft.
With the rear brake engaged, loosen and remove the front sprocket bolt, washer, and sprocket from the countershaft.
Carefully remove the collar from the countershaft.
Carefully remove the collar from the countershaft.

Rear/Driven Sprocket Removal

  1. Lay your rear wheel on a towel with the brake side down.
  2. Coat the sprocket bolts with PB blaster, then flip your wheel and spray the sprocket nuts.
  3. After the PB does its job, loosen and remove the rear sprocket hardware.
Lay your rear wheel on a towel with the brake side down.
Lay your rear wheel on a towel with the brake side down.
Coat the sprocket bolts with PB blaster, then flip your wheel and spray the sprocket nuts.
Coat the sprocket bolts with PB blaster, then flip your wheel and spray the sprocket nuts.
Spray Rear Sprocket Nuts With PB Blaster
Spray Rear Sprocket Nuts With PB Blaster
After the PB does its job, loosen and remove the rear sprocket hardware.
After the PB does its job, loosen and remove the rear sprocket hardware.

Related: How to service the rear master cylinder on your 97-01 CR250.

Chain Removal

  1. Locate the master link, then rotate the chain, so it sits on top of the swingarm.
  2. Lay your left forearm on the chain, with your screwdriver facing the front of the bike.
  3. Align the blade of your screwdriver with the open end of the spring clip.
    • If it was installed correctly, the open end should be facing the back of your bike.
  4. Give the butt of the screwdriver a tap with your rubber mallet and the spring should pop off the pins.
  5. Align your chain breaker, so it pushes the pins toward the bike, and remove the pins
Locate the master link, then rotate the chain, so it sits on top of the swingarm.
Locate the master link, then rotate the chain, so it sits on top of the swingarm.
Lay your left forearm on the chain, with your screwdriver facing the front of the bike.
Lay your left forearm on the chain, with your screwdriver facing the front of the bike.
Align the blade of your screwdriver with the open end of the spring clip.
Align the blade of your screwdriver with the open end of the spring clip.
Give the butt of the screwdriver a tap with your rubber mallet and the spring should pop off the pins.
Give the butt of the screwdriver a tap with your rubber mallet and the spring should pop off the pins.
Align your chain breaker, so it pushes the pins toward the bike, and remove the pins
Align your chain breaker, so it pushes the pins toward the bike, and remove the pins

Sprocket & Drive Chain Inspection

  1. Before you bother cleaning the sprockets and chain, check to see if they are worth keeping.
  2. Check both sprockets for excessive tooth wear.
  3. Check the back sprocket for signs of uneven wear and straightness.
  4. 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.
Before you bother cleaning the sprockets and chain, check to see if they are worth keeping.
Before you bother cleaning the sprockets and chain, check to see if they are worth keeping.
Check both sprockets for excessive tooth wear.
Check both sprockets for excessive tooth wear.
Check the back sprocket for signs of uneven wear and straightness.
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.
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

  1. Lay your chain flat and pull it straight and measure the span of 17 pins.
  2. The span between the 1st and 17th pin should not exceed 10 and 1/8th inch.
  3. 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!
Lay your chain flat and pull it straight and measure the span of 17 pins.
Lay your chain flat and pull it straight and measure the span of 17 pins.
Check the pins and side plates for damage or signs of uneven wear.
Check the pins and side plates for damage or signs of uneven wear.

Clean & Inspect

  1. Clean everything with carburetor cleaner, then rinse with warm water.
  2. Hang your chain, and wrap everything else in a towel to dry.
  3. Clean your countershaft using carb cleaner, a towel, and a tiny screwdriver.
  4. Clean the splines as best as you can.
  5. Once the countershaft is thoroughly wiped down, remove the O-ring, and throw it away.
Clean everything with carburetor cleaner, then rinse with warm water.
Clean everything with carburetor cleaner, then rinse with warm water.
Hang your chain, and wrap everything else in a towel to dry.
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 your countershaft using carb cleaner, a towel, and a tiny screwdriver.
Once the countershaft is thoroughly wiped down, remove the O-ring, and throw it away.
Once the countershaft is thoroughly wiped down, remove the O-ring, and throw it away.

Sprocket & Drive Chain Installation

Rear/Driven Sprocket Installation

  1. Start your installation with the rear sprocket.
  2. Install the sprocket hardware hand tight, then torque the rear sprocket bolts in a criss-cross pattern.
    • Torque to 24 ft-lbs
Start your installation with the rear sprocket.
Start your installation with the rear sprocket.
Install the sprocket hardware hand tight, then torque the rear sprocket bolts in a criss-cross pattern. Torque to 24 ft-lbs
Install the sprocket hardware hand tight, then torque the rear sprocket bolts in a criss-cross pattern. Torque to 24 ft-lbs

Front/Drive Sprocket Installation

  1. Install the new o-ring onto the countershaft.
  2. Grease and install the collar with the groove facing in.
  3. Mount the front sprocket with the flat side facing out.
  4. Install the bolt and washer with the outside markings facing out.
New O-Ring For Countershaft Part Number 91201-ML3-873
New O-Ring For Countershaft Part Number 91201-ML3-873
Install the new o-ring onto the countershaft.
Install the new o-ring onto the countershaft.
Grease and install the collar with the groove facing in.
Grease and install the collar with the groove facing in.
Mount the front sprocket with the flat side facing out.
Mount the front sprocket with the flat side facing out.
Install the bolt and washer with the outside markings facing out.
Install the bolt and washer with the outside markings facing out.

Related: How to bleed the brakes on your 1997-01 Honda CR250.

Chain Installation

  1. Run your chain through the guides, so the ends meet on top of the swingarm.
    • The easiest way I have found for installing an o-ring master link is to drive the pins through the inside plate first.
  2. Place the o-rings on the pins, then slide the pins through the holes.
  3. Then take the inside of the chain breaker to press the outside plate onto the pins.
    • Once the pins are pressed in, install the spring clip.
  4. Align the spring clip, with the closed end facing forward.
  5. With your screwdriver, pry the open end halfway onto the link.
  6. Then push the clip the rest of the way.
  7. Install your chain on both sprockets.
  8. Apply the rear brake, and torque the sprocket bolt.
    • Torque to 20 ft-lbs
  9. Reinstall the sprocket guard and bracket.
Run your chain through the guides, so the ends meet on top of the swingarm.
Run your chain through the guides, so the ends meet on top of the swingarm.
Place the o-rings on the pins, then slide the pins through the holes.
Place the o-rings on the pins, then slide the pins through the holes.
Then take the inside of the chain breaker to press the outside plate onto the pins.
Then take the inside of the chain breaker to press the outside plate onto the pins.
Align the spring clip, with the closed end facing forward.
Align the spring clip, with the closed end facing forward.
With your screwdriver, pry the open end halfway onto the link.
With your screwdriver, pry the open end halfway onto the link.
Then push the clip the rest of the way.
Then push the clip the rest of the way.
Install your chain on both sprockets.
Install your chain on both sprockets.
Apply the rear brake, and torque the sprocket bolt. Torque to 20 ft-lbs
Apply the rear brake, and torque the sprocket bolt. Torque to 20 ft-lbs

If you have any questions or anything to add, please leave them in the comments or on our FaceBook page!

Keep Your ’97-’01 CR250 Running Right!

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