4. LUBRICATION SYSTEM
4-3
SERVICE INFORMATION (90cc/70cc/50cc-4T)
GENERAL INSTRUCTIONS
• The maintenance of lubrication system can be performed with the engine installed in the frame.
• Use care when removing and installing the oil pump not to allow dust and foreign matters to
enter the engine and oil line.
• Do not attempt to disassemble the oil pump. The oil pump must be replaced as a set when it
reaches its service limit.
• After the oil pump is installed, check each part for oil leaks.
SPECIFICATIONS mm (in)
Item Standard Service Limit
Inner rotor-to-outer rotor clearance 0.15 (0.006) 0.2 (0.008)
Outer rotor-to-pump body clearance 0.15～0.2 (0.006～0.008) 0.25 (0.01)
Oil
pump
Rotor end-to-pump body clearance 0.04～0.09 (0.0016～0.0036) 0.12 (0.0048)
TROUBLESHOOTING
Oil level too low Poor lubrication pressure
• Natural oil consumption • Oil level too low
• Oil leaks • Clogged oil filter or oil passages
• Worn or poorly installed piston rings • Not use the specified oil
• Worn valve guide or seal
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