fuel filter YAMAHA YZ250F 2011 User Guide

5-36
REAR SHOCK ABSORBER
REAR SHOCK ABSORBER
REMOVING THE REAR SHOCK ABSORBER
Order Part name Q'ty Remarks
Hold the machine by placing the suitable stand
under the engine.Refer to "HANDLING NOTE".
Seat Refer to "SEAT, FUEL TANK AND SIDE
COVERS" section in the CHAPTER 4.
Silencer Refer to "EXHAUST PIPE AND SILENCER"
section in the CHAPTER 4.
1 Clamp (air filter joint) 1 Only loosening.
2Rear frame 1
3 Bolt (rear shock absorber-relay arm) 1 Hold the swingarm.
4 Bolt (rear shock absorber-frame) 1
5 Rear shock absorber 1
6 Locknut 1 Only loosening.
7 Adjuster 1 Only loosening.
8 Lower spring guide 1
9 Upper spring guide 1
10 Spring (rear shock absorber) 1
11 Bearing 2 Refer to removal section.
B2
9
8 10
11
11

7-4
ENGINE
SPECIFICATIONS OF JET NEEDLE
EXAMPLES OF CARBURETOR SETTING DEPENDING ON SYMPTOMFor USA and CDN
Diameter of straight portion
RichLean
NPQRS TU
Rich 1 richer NDJN-5 NDJP-5 NDJQ-5 NDJR-5 NDJS-5 NDJT-5 NDJU-5
0.5 richer NCVN-4 NCVP-4 NCVQ-4 NCVR-4 NCVS-4 NCVT-4 NCVU-4
STD NDJN-4 NDJP-4 NDJQ-4 NDJR-4 NDJS-4 NDJT-4 NDJU-4
0.5 leaner NCVN-3 NCVP-3 NCVQ-3 NCVR-3 NCVS-3 NCVT-3 NCVU-3
Lean 1 leaner NDJN-3 NDJP-3 NDJQ-3 NDJR-3 NDJS-3 NDJT-3 NDJU-3
Except for USA and CDN
Diameter of straight portion
RichLean
NPQRS TU
Rich 1 richer NFLN-7 NFLP-7 NFLQ-7 NHKR-5 NFLS-7 NFLT-7 NFLU-7
0.5 richer NFPN-6 NFPP-6 NFPQ-6 NFPR-6 NFPS-6 NFPT-6 NFPU-6
STD NFLN-6 NFLP-6 NFLQ-6 NHKR-4 NFLS-6 NFLT-6 NFLU-6
0.5 leaner NFPN-5 NFPP-5 NFPQ-5 NFPR-5 NFPS-5 NFPT-5 NFPU-5
Lean 1 leaner NFLN-5 NFLP-5 NFLQ-5 NHKR-3 NFLS-5 NFLT-5 NFLU-5
Symptom Setting Checking
At full throttle
Hard breathing
Shearing noise
Whitish spark plug
↓
Lean mixtureIncrease main jet calibration no. (Gradual-
ly)Discoloration of spark plug→If tan color, it
is in good condition.
If cannot be corrected:
Clogged float valve seat
Clogged fuel hose
Clogged fuel cock
Check that the accelerator pump operates
smoothly.
At full throttle
Speed pick-up stops
Slow speed pick-up
Slow response
Sooty spark plug
↓
Rich mixtureDecrease main jet calibration no. (Gradual-
ly)Discoloration of spark plug→If tan color, it
is in good condition.
If cannot be corrected:
Clogged air filter
Fuel overflow from carburetor
Lean mixture Lower jet needle clip position. (1 groove
down)
The clip position is the jet needle groove on
which the clip is installed.
The positions are numbered from the top.
Check that the accelerator pump operates
smoothly. (except for rich mixture symp-
tom). Rich mixture Raise jet needle clip position. (1 groove up)
1/4–3/4 throttle
Hard breathing
Lack of speedLower jet needle clip position. (1 groove
down)
1/4–1/2 throttle
Slow speed pick-up
Poor accelerationRaise jet needle clip position. (1 groove up)
Jet needleClip
Groove 7 Groove 6
Groove 5
Groove 4
Groove 3
Groove 2
Groove 1
Leaner
(Standard)
Richer