- Pre-Service Notes
- Exhaust Valve Linkage Assembly
- Exhaust Valve Governor Install
- Flap Valve Assembly
- Right Sub-Exhaust Valve Install
- Connect Valve Linkage
- Left Sub-Exhaust Valve Install
- Test Power Valve Operation
- Exhaust Valve Torque Specifications
- Top End Rebuild Tools List: (Links to Amazon)
- Top End Rebuild Parts List: (Links to Amazon)
How To Install The Exhaust Valve On Your 97-01 Honda CR250
- 4mm Hex Wrench
- Needle-Nose Pliers
- 2-Stroke Oil
- Molybdenum Grease
- Inch-Pound Torque Wrench
- Rubber Gloves
- (Master Tools & Parts List Below)
The Parts You Will Need
- Exhaust Valve Cap O-Ring – Part Number: 91302-001-020
- 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 on Amazon!
- Pictures with captions are after the steps below.
- If you need any help don’t hesitate to ask!
Exhaust Valve Linkage Assembly
Start by assembling the linkage.
- Insert the bushing into the valve link, small side down.
- Install the spring with the spring ends facing up.
- Compress the spring, and rest it in the stop.
- Place the drive pinion on top of the linkage with the pin between the spring ends.
- Apply grease to the driveshaft bushing and driveshaft. Fit the bushing on the driveshaft, and Install the drive shaft partway into the cylinder.
- Align the link assembly, and finish installing the driveshaft.
- Clip the driveshaft into the linkage.
Exhaust Valve Governor Install
- Apply grease to the pinion shaft and bushing. Seat bushing in the crankcase.
- Assemble the governor washers and engage the rack. Install the governor in the crankcase.
- Install pinion shaft with the opening facing in. Double-check the rack and pinion operation.
Flap Valve Assembly
- Apply grease to the flap valve shaft, and partially install it into the cylinder.
- Install the flap valve with the projections facing up. Align and install the flap valve.
- 97-98 – Through the exhaust port.
- 99-01 – Through the cylinder
Right Sub-Exhaust Valve Install
- Apply grease to the exhaust valve shaft, and connect it to the valve.
- Align the valve shaft with the flap valve, and place the sub-exhaust valve on its bore. Apply 2-stroke oil to the valve, then press the valve into the cylinder.
- Turn the valve until the cutout is facing up, and install the stopper bolt hand tight.
- Install bearings with the manufacturer’s marks facing out.
Connect Valve Linkage
- Seat the valve link against the end of the valve so the tab sits in the cutout. Rotate the valve counter-clockwise, and insert a drift into the hole.
- Install the hex bolt and torque to 48 in-lb.
Left Sub-Exhaust Valve Install
Lubricate the left Sub-Exhaust valve with 2-stroke oil. Align the valve with the valve shaft, and press it into the bore.
Lubricate and install the bearings with the markings facing out.
Install the collar with the stepped side facing in, followed by the snap ring.
Lubricate a new o-ring, and install it on the valve cap.
Apply grease to the valve cap threads, and install the cap hand tight.
Test Power Valve Operation
- Tighten the hex bolt on the pinion holder temporarily, and test the operation of the exhaust valve system.
- Loosen the pinion bolt, as you will need to adjust the system after the cylinder is installed.
Exhaust Valve Torque Specifications
- Linkage Hex Bolt – 48 in-lb.
- Pinion Hex Bolt – 48 in-lb.
Top End Rebuild Tools List: (Links to Amazon)
- Piston Pin Puller
- Piston Holder
- Machinists Straight Edge
- Feeler Gauges
- Telescoping Bore Gauges
- Digital Calipers
- Plastic Scraper
- Spark Plug Thread Follower
- Motion Pro Torque Wrench Adapter
- Molybdenum Grease
- Lithium Grease
Top End Rebuild Parts List: (Links to Amazon)
Keep Your ’97-’01 CR250 Running Right!
- Service Specification
- Clutch Replacement
- Carburetor Service
- Engine Top End
- Engine Bottom End
- Front Suspension
- Rear Suspension
- Wheels & Tires
- Kickstarter Inspection
- External Shift Linkage