Yamaha YP250 - Poor Medium and High Speed Performance; Poor Speed Performance

9-3
POOR MEDIUM AND HIGH SPEED PERFORMANCE
TRBL
SHTG
EB902000
POOR MEDIUM AND HIGH SPEED PERFORMANCE
POOR MEDIUM AND HIGH SPEED PERFORMANCE
Refer to “STARTING FAILURE/HARD STARTING” section. (Fuel system, electrical system, compres-
sion system and valve train)
Carburetor
 Improperly adjusted fuel level
 Clogged main nozzle
 Clogged or loose pilot jet
Air cleaner
 Clogged air cleaner element
YP******
POOR SPEED PERFORMANCE
POOR SPEED PERFORMANCE
Ignition system
 Dirty spark plug
 Improper heat range
 Faulty ignitor unit
 Faulty pick up coil
Fuel system
 Clogged fuel tank cap breather hole
 Clogged air cleaner element
 Clooged jet
 Improperly adjusted fuel level
 Improper carburetor air vent hose setting
Compression system
 Worn cylinder
 Worn or seized piston ring
 Cylinder head gasket broken
 Cylinder gasket broken
 Carbon deposit build-up
 Improperly adjusted valve clearance
 Improperly contacted valve and valve seat
 Faulty valve timing
Clutch
 Refer to “CLUTCH SLIPPING/DRAGGING”
section
Engine oil
 Improper oil level (low or over oil level)
 Improper quality (Low oil viscosity)
 Deterioration
 Clogged oil passage
Brakes
 Dragging brake