Baja WD250U Service Manual page 230

(2) Piston and piston ring
• Improper piston ring installation
• Piston ring is worn and out of elasticity
• Piston ring is broken
• Piston is damaged or cracked
(3) Valve, camshaft and crank shaft
• Valve didn't close entirely
• Improper match between valve and valve
seat
• Wrong port timing
• Valve spring is damaged
• Valve camshaft is damaged
• Crank shaft is damaged
(II) Poor idle speed performance
(1) Carburetor
• Starting plug is not closed entirely
• Idle metering jet is loose
• Idle air metering jet is clogged
• Improper idle adjustment
• Improper adjustment of throttle stroke
• Leakage of carburetor
(2) Electric system
• Spark plug is bad
• CDI is bad
• Coil is bad
• Charging coil is bad
• Ignition coil is bad
(3) Valve system
• Improper adjustment of valve clearance
•Core of air filter is clogged
(III) Poor middle and high speed
performance
Refer to "starting trouble/ deficiency" and
"poor idle speed performance" section in
this chapter.
(1) Carburetor
• Wrong needle valve position
• Main jet is clogged or loosened
• Fuel is deteriorated or polluted
• Wrong float chamber oil level
(2) Air filter
• Core of air filter is clogged
(IV) Shifting trouble
1. Shifting difficulty
Refer to "slipping of clutch" and "ablation of
clutch" in this chapter
2. Shifting peddle is clogged
(1) Shifting shaft groups
• Shifting shaft is bent
• Shifting lever group is damaged
(2) Shifting cam, shifting fork
• There is foreign matter in shifting camshaft
recess
• Shifting fork is clogged
• Shifting fork is bent
(3) Driving system
•Driving gear is clogged
• Foreign matter is clogged
• Incorrect driving system installation
3. Shift is out of gear
(1) Shifting shaft groups
• Improper adjustment of limited lever
position
• Limited lever can't back
(2) Fork
•Fork is worn
(3) Shifting cam
• Recess of shifting cam is worn
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