Villiers MARK 12D, Operating Instructions And Spare Parts List

Page: 17 / 53

FAULT FINDING CHART-(
continued).
Sequence of Testing. Possible Trouble.
Engine Four or Eight Strokes.
:5trangler may not be fully
open or taper needle in a
too high position.
Air f
i l t
e
r
may need cleaning.
Check by watchin� for ex­
cessive smoke fro m exhaus;t
pipe or silencer.
Engine Lacks Power.
Engine will not run
Slowly.
Engine Suddenly
Stops Firing.
Mixture too rich.
Engine may four stroke for
a little while after standing
due to ac:cumulation of oil
in crankcase.
Flooding of carburetter.
Engine out of tune, bearings
worn. Unsuitable sparking
plug. Loss of compression.
Incorrect
•·
pe t
r
o i l " mixture.
Excessive carbon deposit on
piston crown and cylinder
head.
Exhaust system choked with
carbon.
Incorrect carburetter se t ti ng
.
Air cleaner choked.
Obstruction in fuel su pp ly .
Incorrect i g n itio n timing.
Brakes binding.
Driving chains too t ight.
Weak mixture due to air
leaks at carburetter stub or
manifold joint. crankcase and
cylinder base joints.
Crankcase drain screw loose
or missing.
Worn crankshaft bearinas or
leaking seal
Ignition timing too tar ad­
vanced.
Sparking plug lead detached.
Plug points bridged by od,
carbon, or deposit caused by
use of leaded petrol.
Short circuit of high t ension
current by water on
H.
T.
lead.
Remedy.
Lower taper needle by mov­
ing to a WEAKER position.
Lower
needle by adjuster
screw fitted in throttle.
Usually ceases when engine
has been running for a few
minutes unless too much oil
has been mixed with the
petroL
Persistent flooding is usually
due to dirt under fuel needle
seating, or sticking fuel
needle, damaged seating or
punctured float.
Overhaul. Replace with re­
commended type.
Tighten cylinder head bolts.
Replace worn piston rings.
Correct mixture is
1
oart oil,
20 parts
pe-;·rol. (Also see
page
3).
Decarbonize.
Clean out silencer and ex­
haust pipes
Check and
adjust.
Wash in petrol, drain and
dip in thin oil.
Clean out tap, fuel pipe and
filters.
Check
and adjust.
A
dj
us
t
.
·
A
dj
u st
.
Tighten all joints
Tighten or repLiice
Replace.
Correct.
Replace and tighten nut
Clean or replace
Dry out.