Jet Needle Groove Position Adjustment; Carburetor Setting Parts - Yamaha YZ85W1 Service Manual

ENGINE
JET NEEDLE GROOVE POSITION
ADJUSTMENT
Should the engine be hard to run smoothly at
intermediate speeds, the jet needle
adjusted. If the mixture is too rich or too lean at
intermediate speed operation, irregular engine
operation and poor acceleration will result.
Whether or not the richness of the mixture is
proper is hard to be determined by means of
the spark plug and therefore, it should be
judged from your feeling of actual engine oper-
ation.
Standard clip position
1. Too rich at intermediate speeds
Rough engine operation is felt and the
engine will not pick up speed smoothly.
In this case, step up the jet needle clip by
one groove and move down the needle to
lean out the mixture.
2. Too lean at intermediate speeds
The engine breathes hard and will not pick
up speed quickly.
In this case, step down the jet needle clip
by one groove and move up the needle to
enrich the mixture.

CARBURETOR SETTING PARTS

Part name
Main jet
(STD)
Pilot jet
(STD)
Jet needle
Refer to the
following table
about the change in
the air-fuel mixture
ratio due to a
different jet needle.
9-4
TUN
No.2 groove
Size Part number
Rich #148 4MX-14943-87
#145 4MX-14943-36
#142 4MX-14943-86
#140 4MX-14943-35
#138 4MX-14943-85
#135 4MX-14943-34
Lean #132 4MX-14943-84
Rich #48 4MX-14948-06
#45 4MX-14948-05
Lean #42 4MX-14948-04
NBLE 5PA-14916-LE
NBLF 5PA-14916-LF
NBLG 5PA-14916-LG
NBKE 5PA-14916-KE
NBKF 5PA-14916-KF
NBKG 5PA-14916-KG
must be