Spark Plug(s)
Engine misfire, or generally poor operation, is often
caused by spark plug(s) in poor condition or with in�
correct spark gap setting. Spark plug(s) should be
checked after each 1 00 hours of operation. Replace a
spark plug if inspection reveals fouling or excessive
deterioration.
Always clean area around spark plug before re�
moving it to prevent dirt from entering engine. Use a
spark plug wrench to remove and install plug(s).
Check condition of plug(s). Good operating condi
tions are indicated by a light coating of gray or tan
deposit. A dead white, blistered coating could indicate
engine overheating. A black coating could indicate an
"overrich" fuel mixture caused by a dogged air
cleaner, or improper carburetor adiustment.
Replace spark plugs that are not in good condition.
Never sandblast, wire brush, scrape or reinstall spark
plugs in poor condHion. Best results are obtained w ith
new plugs.
Always check spark plug gap before installing new
plug(s) or reinstalling orignial plug(s). Use a spark
plug gap gauge ,to adjust electrode air gap to speciM
fleation for engine.
Tractor M odel
200-Series
. . . . . . . . . . . . . . . . . . . . . - - . . . . . . _ . . . . . . .
4 1 7 -Series
_ . . _ . . . . . . . . - . . . . . . . _ . - . . . . . . . .
308
3 1 0,
Model
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3 1 2, 4 1 4, 4 1 6 Models
. . . . . . . . . _ . .
Tighten spark plug(s) to:
Plug
.030 in.
.025 in.
.025 in.
.035 in.
200-Series, 417 Model - 1 5 ft. Ibs. (20 Nm)
Gap
(.8 mm)
(.6 mm)
(.6 mm)
(.9 mm)
308, 3 1 0, 3 1 2, 4 1 4, 4 1 6 Models - 22 ft. Ibs. (30 Nm)
Breaker Points and Condenser
Following information does not apply to 200MSeries
and 308 Mode! tractors, which have an engine with
breakerless electronic ignition. This system requires no
maintenance.
Condition and adiustment of breaker points greatly
affects engine operation. If point surfaces are burned
or badly oxidized, little or no current will pass; as a
result, engine may not operate at all, or if it does run,
it is likely to "missll, particularly at full throttle. An
improper engine breaker point gap can also result
in erratic engine operation, since an incorrect gap
changes ignition timing.
' Engine breaker points should be inspected, cleaned,
and gap reset at intervals shown in Maintenance
Checklist. Points that are In poor condition due to
excessive pitting or burning should be replaced.
Primary function of condenser is to minimize a rc
ing across breaker points. Under normal operating
conditions, a small amount of metal transfer (pitting)
will occur between point surfaces. If condenser fails,
excessive pitting or burning of points will occur over
a short period of time. A shorted condenser grounds
ignition system and results in no output voltage to
fire spark plug(s). Condenser is usually replaced each
time breaker points are changed.
Access to breaker points requires a significant
amount of disassembly on some engines and, in some
cases, special tools. In addition, other adiustments
affecting engine timing may be necessary after reM
placing or adjusting breaker points. For these reasons,
it is suggested that ignition system service be per
formed by an authodzed dealer.
Carburetor Adjustment
Carburetors are adiusted at factory and should not
have to be reset. If a condition is noted as outlined in
following "Carburetor Adjustment Chart", carburetor
should be readiusted immediately. Continued ope raM
tion with incorrect carburetor settings can lead to
fouled spark plugs, overheating, excessive valve wear
or other problems. If black exhaust smoke is noted,
check air cleaner first - an 'Joverrichll mixture is
usually caused by a poorly serviced, clogged air
cleaner element, not an improperly adjusted carM
buretor.
Correct carburetor adjustment requires a significant
amount of knowledge as well as special equipment,
such as a good tachometer. In addition, other adiust�
ments, such as governor settings, may also be neces�
sary after adiusting carburetor. For these reasons, it is
suggested that carburetor adjustments be performed
by an authorized dealer.
CONDITION
Black, sooty exhaust smoke, engine sluggish.
B.
Engine misses and backfires at high speed
.
C"
Engine starts� sputters and dies ·under cold
we9ther starting.
D.
Engine runs rough or stalls at idle speed.
POSSI B LE CA USE/P ROBABLE R EM EDY
Mixture too rich - readjust main fuel needle.
B. Mixture too lean - readjust main fuel needle.
C. Mixture too.. lea n ' - readjust main fuel needle.
D.
Idle speed too low or improper idle adjust
ment - readjust
speed
then idle fuel needle
if needed.
Carburetor Adjustment Chart
Fuel Filter
On 3 1 0, 3 1 2, 41 4, 4 1 6, 4 1 7 Models, a fine-mesh
screen type stra iner is i ncorporated into fitting at
bottom of fuel tank, which filters foreign matter from
gasoline before it reaches carburetor. This strainer
normally requires service only if fuel supply becomes
severely contaminated.
On 200�Series and 308 Model, engines have an in
line fuel filter, located near carburetor. This filter
should be replaced after each 1 00 hours of operation
or at 1 year intervals, whichever occurs first.
Always clean area around fuel cap before remov
ing it to prevent excessive amounts of dirt from enter
ing fuel system. Also insure that fuel storage contain
er you are using is clean and in good condition.
Fuel filter gives only limited protection against
moisture in fuel system. Keep fuel tank full during
winter operation, when cold a'nd damp weather Con
ditions can cause moisture to condense in tank.
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