Honda CB900F Service Manual page 427

TROUBLESHOOTING
ENGINE LACKS POWER
Possible cause
1. Raise wheel off the ground and spi n by - - - Wheels do not spin
----I._
hand free ly
I
Wheel spins f ree ly
t
Brake dragging
Worn or da maged wheel bea ring
2. Check t ire pressure - - - -- - - - - - - Pressure low
-----..., ~ ~
• Faul ty t ire va lve
I
Pun ct ured tire
Pressure no rma l
•
3. A cce lera te rapid ly fro m low to seco nd
I
Eng ine speed red uced whe n clutch is
rele ase d
•
- - - Engine sp eed does-
n't change accord-
ingly when clutch is
released
Clutch slipping
Worn clutc h discs/p lates
Warped clutch d iscs/p lates
Weak cl utch spring
Addit ive in engine o il
------..., ~ .-
• Faul ty ECM
Faulty ignition pulse gen er at or
4. Accelerate lightly - - - - - - - - - - - - Eng in e speed does - - - .
I
not increase
Engine speed increase
•
5. Check ig nit io n t im ing - - -- - - - - - - - lnco rr ect
I
Co rrect
•
Ai r clea ner dirty
Rest ri ct ed fuel flow
Clogged muffler
Pinched fuel t ank br eath er
6. Test cylinder com pression - -- - - - - - - Inco rrect ---------c~ ~
.
Valve st uck ope n
I
Worn cy li nder and piston ri ngs
No rmal Leakin g head gas ket
t
Im prop er va lv e t iming
7. Inspect f uel flow - - - - -- - - - - - -
Abnormal--------1 ~ .-
• Fau lty pressu re regulator (Sect io n 51
I
Normal
t
8. Inspect t he fuel injector - - - - - - - - - -
A bn or m a l--------1~.-
• See section 5
I
Norma l
•
9. Rem ove spark pl ugs - - - - -- -- - - - Fo ule d or discolored
---1 ~ ~
•
Faul ty spa rk plug
I
Not fo uled or d isco lored
•
10. Check oil lev el and condition - - - - -- - - Incorrect
-------~ ~
• Oi l level too high
I
Oil leve l too low
Correct Contamin ated oil
t
11. Rem o ve cy linder head cove r and inspect - - - Valve t rain not lubri- - - - . -
lubrication cated properl y
I
Valv e t rain lu brica ted properly
•
21-2
Clogged oil passage
Clogged oil co nt ro l o rifice