The location of the pilot screw for the idle adjustment.

This screw adjusts fuel and air.

The screw is situated at the left side on the bottom of each carburetor. Just above the rubber inlet to the cylinder head. What is shown is the BD34 carburetor of a 1982 Euro model. The XZ400 had the same carburetor but with different jets, and no fuel pump. See XZ400 topic on this website.

On 1982 US XZ550’s the air valves were capped to prevent tampering with them. By now most of the caps have been removed by owners or mechanics.

The pilot screw assembly consists of 4 parts; plug, spring, washer, O-ring. Do not lose the O-ring! It tends to stay in the carb body and may easily be lost when blowing out the passages. The factory setting of this plug on Euro 1982 XZ550 models is 2,5 full turns out from lightly seated.

Note that the 1983 550 model had a different carburetor, the BD36.

Sander