Sym HD 125 Service Manual page 80

Tighten 4 nuts and washers on the cylinder head
upper side, and then tighten 2 cylinder head
mounting bolts of cylinder head side cover.
Torque value: 2.0~2.4kgf-m
Install and tighten spark plug
Torque value: 2.0~2.4kgf-m
Caution
This model is equipped with more precision
4-valve mechanism so its tighten torque can not
be exceeded standard value in order to avoid
causing cylinder head deformation, engine noise
and leaking so that motorcycle's performance be
effected.
Install cam chain on to sprocket and align the
timing mark on the sprocket with that of cylinder
head.
Align sprocket bolt hole with camshaft bolt hole.
Tighten the sprocket mounting bolt.
Caution
Make sure timing marks are matched.
Install a new O-ring onto thermostat and tighten its
mounting bolts.
Loosen sprocket chain tensioner and let it contact
with chain plate tightly. Tighten the bolt cap of
tensioner adjustment hole.
Install Air Injection system (AI) pipe. (2 bolts)
Install carburetor insulator onto carburetor and
tighten clamp strip bolt. Install the vacuum hose
of carburetor insulator.
To this chapter contents
Hole cap of adjustment bolt
Vacuum tube
6. CYLINDER HEAD/VALVE
2 Insulator bolts
Cylinder head mounting bolts
AI. Pipe bolts
4 Nuts
Timing mark
Thermostat bolt
Clamp strip
6-13