1997-2001 Honda CR250 – Bottom End Service – Part 1: Removal & Disassembly

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1997 - 2001 Honda CR250 - Bottom End Service - Part 1 - Removal And Disassembly

How To Remove And Disassemble The Crankcase On Your 97-01 Honda CR250

1997 - 2001 Honda CR250 - Bottom End Service - Part 1 - Removal And DisassemblyThe Tools You Will Need

  • 8mm Socket
  • 14mm Socket
  • 22mm Socket
  • Mallet
  • Wood Blocks
  • Towels
  • Big Hammer
  • Plastic Scraper
  • Flat Razor
  • Dremel with Sanding Disc
  • WD40
  • Paper Towels
  • Safety Glasses

The only specialty tool you will need is a case splitter, and you can get one through our partners here.

Pre-Service Notes

  • Put your bike on a sturdy stand and drain oil and coolant.
  • I recommend opening the Bottom End Service Specifications 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!

Bottom End Removal

  1. You have three bolts attaching the bottom end to the frame, two mounting bolts, and the swingarm pivot shaft.
  2. Start by removing the swingarm pivot shaft first, because I have never had one come out easy.
  3. You may find yourself with a seized shaft. The only thing you can do is hose it down with anti-seize, then wait, then hit the bolt with the biggest hammer you have, then repeat as needed.
  4. You will need a new pivot bolt, but they are not too expensive.
    Remove the two lower mounting bolts, and keep track of their direction for install.
  5. Remove the engine from the frame. The swingarm may be resting on the rear of the case, so lift the front end first and give it a jiggle. But do not lift the case by the crankshaft like this impatient idiot.
  6. With the case removed, clean and inspect the frame.
1. Two Mounting Bolts and Swingarm Pivot Bolt
You have three bolts attaching the bottom end to the frame, two mounting bolts, and the swingarm pivot shaft.
2. Remove Pivot Bolt First
Start by removing the swingarm pivot shaft first, because I have never had one come out easy.
3. Pivot Bolt Will Be Stuck
You may find yourself with a seized shaft. The only thing you can do is hose it down with anti-seize, then wait, then hit the bolt with the biggest hammer you have, then repeat as needed.
4. Remove Mounting Bolts
Remove the two lower mounting bolts, and keep track of their direction for install.
5. Remove Crankcase From Frame
Remove the engine from the frame. The swingarm may be resting on the rear of the case, so lift the front end first and give it a jiggle. But do not lift the case by the crankshaft like this impatient idiot.

Crankcase Disassembly

  1. Lay your crankcase on your blocks with the left side facing up. Loosen the 11 crankcase bolts in a criss-cross pattern, ¼ turn at a time until they are all loose.
  2. The crankcase bolts vary in length, so outline the case on cardboard or styrofoam and place your bolts accordingly.
  3. Assemble your crankcase splitter and attach it to the case.
  4. Remember to keep the splitter parallel to the case.
  5. Begin tightening the splitter nut.
  6. After every turn, firmly tap the case seam with a rubber mallet. Make sure to check the case gap frequently if the case is separating unevenly, back out the splitter nut to remove pressure from the case. I had to tap aggressively on the front of the case where a dowel had seized.
  7. With the cases separated, remove the two alignment dowels, o-ring, and gasket material.
6. Loosen Case Bolts
Lay your crankcase on your blocks with the left side facing up. Loosen the 11 crankcase bolts in a criss-cross pattern, ¼ turn at a time until they are all loose.
7. Organize Case Bolts
The crankcase bolts vary in length, so outline the case on cardboard or styrofoam and place your bolts accordingly.
9. Split Case
Assemble your crankcase splitter and attach it to the case.
8. Assemble Case Splitter
Remember to keep the splitter parallel to the case.
9. Split Case
Begin tightening the splitter nut.
10. Tap With Mallet
After every turn, firmly tap the case seam with a rubber mallet. Make sure to check the case gap frequently if the case is separating unevenly, back out the splitter nut to remove pressure from the case. I had to tap aggressively on the front of the case where a dowel had seized.
11. Remove O-ring and Dowels
With the cases separated, remove the two alignment dowels, o-ring, and gasket material.

Transmission Removal

  1. Take every precaution you can when handling the transmission. Keep it oiled, wrapped, and clean at all times.
  2. Remove the two shift fork shafts, followed by the shift drum, and the shift forks.
  3. Remove the main shaft and countershaft as a unit, keeping the gears meshed.
  4. Wrap the assemblies in a towel and set aside.
12. Remove Shift Shafts
Take every precaution you can when handling the transmission. Keep it oiled, wrapped, and clean at all times.
13. Remove Shift Fork
Remove the two shift fork shafts, followed by the shift drum, and the shift forks.

14. Remove Other Shift Fork

15. Remove Shift Drum
Remove the main shaft and countershaft as a unit, keeping the gears meshed.
16. Remove Mainshaft And Countershaft
Wrap the assemblies in a towel and set aside.

17. Keep Shafts Meshed

Crankshaft Removal

  1. Flip the right crankcase, so the outside is facing up, and place a layer of towels under the crankshaft. Attach the crankcase splitter with WASHERS… and press the crankshaft out of the case.
  2. Again, remember to keep the splitter parallel to the case.
  3. If your main shaft bearing comes out with the crankshaft, you will need to use your bearing splitter to remove the bearing from the shaft.
18. Assemble Splitter On Right Side
Wrap the assemblies in a towel and set aside.
19. Press Crankshaft Out Of Case
Again, remember to keep the splitter parallel to the case.
20. Keep Pressing
If your main shaft bearing comes out with the crankshaft, you will need to use your bearing splitter to remove the bearing from the shaft.

Clean & Inspect

  1. The mating surfaces must be spotless and smooth to ensure a tight seal. Start by removing all gasket material from the mating surfaces with part cleaner and a plastic scraper. With the big pieces gone, move onto the tough spots with a flat razor, taking extra care not to gouge the surface.
  2. With all the gasket material gone, give the surface a once over with a fine grit sanding disk. If you don’t have a Dremel, 600 grit emery paper will work just fine. You want to have a smooth almost mirror finish when you are done.
  3. This case has quite a few rough spots leftover from casting. I have the equipment and the time, so I am going to smooth those out while I have to opportunity.

21. Clean Case Halves22. Sand With Dremel of 600 grit Paper 22.1 Dremel Left Over CastingRelated: How to service the rear swingarm bearings on your 97-01 Honda CR250.

Remove Seals

  1. Remove the oil seals from the crankcase. Make sure to use a towel to protect the body.
  2. Thoroughly wash the crankcase with water and solvent. Thoroughly dry with compressed air, and coat with a layer of WD40.

23. Remove Oil Seals 24. Clean And Coat with WD40

Inspect

  1. With your case clean and shiny, check for any unusual wear or cracking. Inspect the crankshaft for cracks, rubbing, pitting and heat damage.
  2. Check the connecting rod for play.
  3. If something doesn’t look right, take your crankshaft to a machine shop or dealership to check the runout and connecting rod radial clearance.
  4. This crankshaft is nonrepairable, and if it is out of spec, you need to replace it entirely.

25. Inspect Crankshaft

← Intro: Tools & Prep

Part 2: Transmission →

Keep Your ’97-’01 CR250 Running Right!

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