Gapping And Installing The Spark Plug; Reading Spark Plugs - Polaris 1999 Sportsman 400 Service Manual

86
5. Insta ll the special 5/8 in. s park plug socket onto
the spark plug. Ma ke sure
it
is correc tly sea ted and
insta ll an o pen end wrench (tool kit) or soc ket han-
d le to remove the spark plu g.
6. Inspect the plug ca refully. Look for a brok en
center porcelain. excessively eroded electrodes and
excessive carbon or oil fouling.
NOTE
Spark p lug cleaning with the
H se
of
(l
sand-blast type device is
11 0 1
recom -
mended. While thi s type
(~r
cleaning is
thorough, the pl ug
II1I1S!
be com pletely
free ofa ll abrasive cl eaning materia l
when do ne. If
not,
if is possiblefo r the
cleaning material to Ja il into the cyl-
imler during operation and cause
da mage .
G a ppi ng an d In st a lling Ihe Spark Plug
Carefully adj ust the electro de gap o f a new spark
plug to ensure a reliable, consistent spark. Use a
specia l spark plug gapping too l and a wire feeler
ga uge.
I. Make sure the sm a ll termina l (Figure 87) is at-
tach ed to the end of the plug.
2. Insert a wire feeler gauge between the ce nter and
side electrode of the plug (Figu re 88) . 11,e correc t
gap is listed in Table 6. If the gap is correct, there will
be a slight drag felt as the wire is pulled throu gh. If
there is no dra g, or the gauge wi ll not pass through.
bend the side e lectrode with a gapping too l (F igure
89) 10 set the proper gap listed in Tab le 6.
3. Appl y a light coa ting of antiscize com poun d to
the threads of the spa rk plug before installing
it.
Do
not lise engi ne oil on the plug threads.
C·/uTiON
The cylinder head is aluminum and
cross -threading of'he spark plug
call
eas ily da mag e it.
4 . Use the same tool set-up used during rem oval
and screw the spark plug in
by
hand unti l it scats.
Very litt le effort is req uired . If force is necessary.
the plug is cross-threaded-e-stop, unscrew it and try
again.
5. Tighten the plug un til it scats
0 11
the spark plug
ho le in the cylinder hea d. then tight en it an add i-
tion al 1/4 to 112 tom .
CHAPTER THREE
,
NOTE
Do not over tighten. This will only
squas h the gasket and des troy its seal-
ing
abil i ty.
6. Insta ll the spark plug cap and lead and cap o nto
the spa rk plug. Rotate the cap slightly in bo th direc-
tion s and make sure it is attac hed to the spark plug
as we ll as the sea ling surface of the cy linde r head .
Read ing Spa rk Plugs
Read ing the spar k p lug can provid e a sig nificant
amoun t of information regarding engin e perfor-
mance .
A
ca reful exam inat ion of
a plug
that has
bee n in use wi ll provide an indicati on of spa rk plug
opera tion (hea t range), air/fuel mixt ure composition
and engi ne condition (oil co nsum ption, piston .
c tc.). If the plug is new. operate the ATV under a
medium load for a sho rt perio d. Avoid prolonged
idling before shutting olT the engine. Remove the
spark plug as describe d in this chapter. Exa mine the
plug and compare it to those in Figure 90.
If the plug is being read to determine if the carbu-
reto r jetting is correct. start with a new plug and op-