2. Remove the air filter covers. There are four screws holding each cover in place. Remove the left cover first.
3. Loosen the clamps on the carburetor boots. There are four clamps, one on each carburetor. Use the 17mm wrench to loosen the clamps.
4. Remove the carburetor boots. Be careful not to spill any fuel.
5. Remove the carburetors. There are four bolts holding each carburetor in place. Use the 19mm wrench to remove the bolts.
6. Inspect the carburetors. Check for any damage or wear. Clean the carburetors with carburetor cleaner and a brush.
7. Reinstall the carburetors. Reverse the order of the steps above.
8. Adjust the idle speed. Start the engine and let it warm up. Turn the idle speed screw on each carburetor until the engine idles at 1,200 RPM.
9. Adjust the air/fuel mixture. Turn the air/fuel mixture screws on each carburetor until the engine runs smoothly.
10. Reinstall the air filter covers.
11. Test ride the motorcycle. Make sure the engine runs smoothly throughout the entire RPM range.
Here are some additional tips for adjusting carburetors on a 1981 Honda CB900C:
* Use a spark plug gap gauge to set the spark plug gap to .035 inches.
* Check the fuel level in the carburetor bowls. The fuel level should be between 1/8 inch and 1/4 inch below the top of the bowl.
* Use a vacuum gauge to synchronize the carburetors. The vacuum readings should be within 2 inches of each other.
* If you are not comfortable adjusting carburetors, take the motorcycle to a qualified mechanic.
