Procedure before carburetor adjustment
1. Engine has to be suitably warm before you start the tuning process. If the engine is not warmed properly it can lead to bad tuning. Before you start the adjustment it is essential that you take it out for 6-7 km ride. Try to ride in high speed so that the engine gets warmed up.2. Before starting the tune also note down the current state of your pilot screw. Screw the pilot screw clockwise (with loose hands) till it does not screw anymore. Note the number of turns and then bring it back to its current position. Be very careful not to apply pressure at any point, or you may end up damaging the pilot screw seating. For noting the current position of the idle screw just note the number of screw threads showing above the bolt.
Carburetor (UCD33) adjustment setting / tuning
1. Start the engine and turn idle screw slightly clockwise to increase the idle RPM. Increase the Idle RPM to 1200-1400 RPM.2. Now start turning the pilot screw clockwise in half turns. You can slightly scratch the topside of the pilot screw so that you can count the turns without getting confused.
3. As you keep turning the pilot screw the fuel mix will turn leaner and the engine will start skipping.
4. Now comes the tricky part. You have to stop turning just when you feel the engine is going to shut down. If the engine shuts down it will get very difficult to start it again without bringing the pilot screw to its original position. So ensure that you stop at the right time
5. This is the leanest setting your engine can have. Now start turning the pilot screw anti clockwise in half turns.
6. As you turn the pilot screw you will notice that engine sound will increase with the turns as the rpm increases. People can see the RPM going up. Keep turning the pilot screw till you can hear the engine sound increasing.
7. Stop at the point where the engine sound does not change in spite of your turning the pilot screw. You can stop when the RPM stops increasing in spite of turning the screw. Usually this happens at 3-4 full turns.
8. Now start turning the idle screw button anti clockwise.
9. As before keep turning it till you feel that the engine is going to shut down
10. Set the idle screw quarter turn above that setting. In case you have RPM meter you can keep the idle at 800~1000 RPM.
Done!
After adjustment settings are done
Go for a ride. Your bike should be performing better than before and should feel lighter.The picture is from a 500 Bullet but the carb is identical.
