How to Remove, Service, and Install your 1994 through 2001 Yamaha YZ125 Exhaust Valve Governor.
The Tools You Will Need
- 4mm Hex Wrench
- Needle-nose Pliers
- 2-Stroke Oil
- Moly Grease → https://amzn.to/40eacJw
- Inch-Pound Torque Wrench → https://amzn.to/4j9LDpC
- Rubber Gloves
- Safety Glasses → https://bulltru.com
The Parts You Will Need
- New Right Crankcase Cover Gasket → https://amzn.to/47M2E4m
Pre-Service Notes
- 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! → https://amzn.to/4h4lDKq
- Pictures with captions are below after step.
- If you need any help don’t hesitate to ask!
Exhaust Valve Governor Removal
Your exhaust valve governor sits at the bottom front of your right crankcase. I recommend cleaning one component group at a time to keep things organized.
The Three Component Groups Are:
- Drive Linkage Assembly
- Right Crankcase Cover
- Governor Rotating Assembly
Drive Linkage Assembly
- Start by removing the two screws holding the governor fork to the push rod assembly.
- Remove the push rod assembly.
- Clean and inspect the pushrod assembly for cracks or bends, and check that the pivot points move freely.
- Place your connecting rod assembly in a zip-lock bag and spray it down with penetrating oil to deep clean the pivot points.
Right Crankcase Cover
- Clean the pushrod bore, and check for any burs, cracks, or obvious damage.
- Test the bearing by placing your governor in the bore and giving it a good spin.
- The governor should spin freely without wobble.
- If your bearing is damaged, it needs to be replaced.
- If everything checks out, clean the cover and reinstall the push rod assembly.
Drive Linkage Assembly – Installation
- Install the governor fork with the bar facing the bearing.
- Apply thread lock, and torque the fork screws to 44 inch pounds.
- Install the governor, and test the operation.
Governor Rotating Assembly
- The exhaust valve governor is a stack of thrust bearings, washers, and a collar, all held together with a single pin at the end.
- Disassemble the governor, and lay each piece out in order, then clean and inspect each piece while you reassemble.
- Install the governor in the crankcase cover.
Governor Stack for 1994-1998 Models
- Gear
- Spring
- Spacer
- Plate
- Washer
- Thrust Bearing
- Washer
- Collar
- Washer
- Thrust Bearing
- Washer
- Retainer Weight
- Balls & Retainer
Governor Stack for 1999 -2001 Models
- Gear
- Spring
- Plate
- Thrust Bearing
- Washer
- Collar
- Washer
- Thrust Bearing
- Washer
- Retainer Weight
- Balls & Retainer
Governor Rotating Assembly – Installation
- Install a new gasket, and install the crankcase cover.
- Apply thread lock and install the drive shaft bolt.
- Install a new gasket, and install the linkage cover.
If you have any questions, please let me in the comments, or send me a DM!
| ← Cylinder Head Install | Break-In → |
Follow Fix Your Dirt Bike!
