Honda NU50 - Cylinder Head, Cylinder, Piston Service Info

G":nHONDA
~~ NU50· NU50M
6.
CYLINDER HEAD /
CYLINDER/PISTON
I
l~
SERViCE INFORMATION
TROUBLESHOOTING
CYLINOER HEAO
CYLINOER/PISTON
6-1
6-1
6-2
6-3
SERVICE INFORMATION
GENERAL
All cylinder head, cylinder and piston mainlenance and impection can be done with Ih~ engine installed,
Belore disJssernbly. clean the engine to prevent dirt and dust Irorn entering the cylinder and crankcase.
Remove i'lil gaske1 material from lhe mating surfaces of the cylinder head. cylinder and crankcase.
SPECIFICATIONS
(1.5748-1.5754)
(1.5728-1.5732)
(0.0016-0.0022)
(0.3938-0.39401
(0.3935-0.3937)
(0.0001-0.0005)
(0.006-0.014l
(0.5514-0.5519)
STAN DAR 0 mm (,,;n~I,--- -+_~S~E~R~V~'~C~E:..::L~' M::-' T=,m~m':..C(;~n~I __ ,
0.10 (0.004)
40.050 11.5768)
39.900 (1.5709)
0.100 (0.0039)
10.030 (0.3949)
9.970 (0.3925)
0.040
(0.0016)
0.60 (0.024)
14.030 (0.55241
40.000-40.015
39.950-39.960
0.040-0.055
1 0.002-1 O.OOB
9.994-10.000
0.002-0.012
0.15-0,35
14.005-14.017
ITEM
Cylinder head warpage
Cylinder bore
p. 0 0 (4 mm from bottom of
IHon . . piston skirtl
Cylinder-Ie-piston clearance
Piston pin hole 1.0.
Piston
Dm 0.0.
PistorHo'p1ston pin cle<lrancc
Piston ring end gap (tOP, second)
Connecting rod small end 1.0.
TORQUE
Cylinder h~ad bolt:
TROUBLESHOOTING
CompreSSion too low, hard starting or poor
performance ilt low speed
1. Blown cylinder head gasket
2. Loose spark plug
3. Worn, s1Uck or broken pistOll rings
4.
Worn or damaged cylinder ilnd piston
5. Faulty feed valve
Compression
too high, overheating or knocking
Abnormal noise·piston
1. Worn cylinder and piston
2. Worn piston pin or piston pin hole
3.
Worn connecting rod small end bearing
Abnormal noise
1. Worn, stuck or broken piston rings
2. Worn
or damaged cylinder
1. Excessive carbon buildup in cylinder head
or on piston top
Date of Issue: Nov., 198t
© HONDA MOTOR CO .. LTD.
5J
6-1