Poor Medium-And-High-Speed Performance; Engine; Fuel System; Faulty Clutch - Yamaha 2004 YP400 Service Manual

POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE/

EAS00848
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE
Refer to "STARTING FAILURE/HARD STARTING".

ENGINE

Air filter
• Clogged air filter element
EAS00853

FAULTY CLUTCH

ENGINE OPERATES BUT SCOOTER WILL
NOT MOVE
V-belt
• Bent, damaged or worn V-belt
• Slipping V-belt
Primary pulley cam and primary pulley
slider(s)
• Damaged or worn primary pulley cam
• Damaged or worn primary pulley slider
Transmission gear(s)
• Damaged transmission gear

CLUTCH SLIPS

Clutch shoe spring(s)
• Damaged, loose or worn clutch shoe spring
Clutch shoe
• Damaged or worn clutch shoe
Primary sliding sheave
• Seized primary sliding sheave
FAULTY CLUTCH

FUEL SYSTEM

Throttle body
• Faulty diaphragm
Fuel pump
• Faulty fuel pump

POOR STARTING PERFORMANCE

V-belt
• V-belt slips
• Oil or grease on the V-belt
Primary sliding sheave
• Worn primary sliding sheave
Clutch shoe
• Bent, damaged or worn clutch shoe

POOR SPEED PERFORMANCE

V-belt
• Oil or grease on the V-belt
Primary pulley weight(s)
• Faulty operation
• Worn primary pulley weight
Primary fixed sheave
• Worn primary fixed sheave
Primary sliding sheave
• Worn primary sliding sheave
Secondary fixed sheave
• Worn secondary fixed sheave
Secondary sliding sheave
• Worn secondary sliding sheave
9 - 3
TRBL
SHTG