Relationship With Throttle Opening - Yamaha YZ125(R)/LC Owner's Service Manual

Table of Contents

Relationship with throttle opening

The flow of the fuel through the carburetor main

system is controlled by the main jet and then, it is

further regulated by the area between the main

nozzle and the jet needle. On the relationship

between the fuel flow and the throttle opening,

the fuel flow relates to the straight portion of the

jet needle at full closed~1/8 throttle, to the 1st

tapered portion at 1/4 throttle, to the second

tapered portion at 1/2 throttle, to the third tapered

portion at 3/4 throttle and to the fourth tapered

portion at full open.

Therefore, the fuel flow is balanced at each stage

of throttle opening by a combination of the jet

needle diameter and clip position.

6CHY6-82-3rd groove

6CHY6-82-2nd groove

6CHY6-83-3rd groove

å Lean (larger diameter)

∫ Rich (smaller diameter)

1 Full closed

2 1/4 throttle

3 1/2 throttle

4 3/4 throttle

a Main nozzle