Valve Clearance Measurement - Polaris 1999 Sportsman 400 Service Manual

L UBR IC ATION, M AI NT EN A NC E AN D TUNE- UP
83
rem ove the spark plug. Perform the procedures in
the follow ing order:
I. Replace the air filter eleme nt. Clea n the foam
pre-fi lter element
if
necessary.
2. Chec k and adj ust the valve clearances.
3, Chec k or replace the spark plugs,
4 , Chec k and adjust the carburetor idle spe ed,
Air Filter Ele ment
If necessary, replace the a ir filter and clean the
pre- filter, as describ ed in this c hapte r. before per-
form ing the following tunc- up proce d ures.
Valve Clea rance Meas urement
T he correct va lve clearan ce is listed in Ta ble 6,
T he ex haust va lves are located at the front of the en-
gine and the intake valves arc located at the rear of
the engine.
The photographs in the following pro cedures
show the eng ine removed from the fram e for clarity.
It
is not necessary to remove the eng ine to adj ust the
va lves.
NOTE
Valve clearance me asurement and ad-
j ustment must be performed with the
engine cool, at room temperature (be-
low
35'
C195° F) ,
I, Place the ATV on a level sur fac e and ap ply the
pa rking brake, Block the wheels to kee p it from roll -
ing in eithe r direc tion.
2,
Remo ve the seat and front fende r as described in
Chapt er Fifteen ,
3, Remov e the fuel tank as describ ed in Chapter
Six,
4 . Remove spark plug as described in this chapter.
T his
will
ma ke it easier to rotat e the eng ine. Place a
piece of duct tape o ver the spark plug hole to pre-
ve nt the entry of deb ris,
5. Remo ve the screws sec ur ing the cylinder head
cover (Fig ure 77) and remo ve the cy linder head
co ver and gasket.
6. Rem ove the plug from the timi ng inspect ion
hole (Figure 78 ),
7, Position the pisto n at top de ad cente r (T DC) on
the compress ion stroke
as
follows:
a , Us ing th e recoil starter, slow ly pull o n the re-
coil handle and observe the o pening and clos-
ing of both sets of valves.
b. Stop ro tating the eng ine when both sets of in-
tak e and exhau st va lves are closed.
c. Verify that the
tw o raised
pins on the cam -
sha ft spro cket are parall el w ith the rocke r ann
cov er gasket surface ( Figure 79 ), The ca m-
shaft lo bes sho uld be facing dow n awa y from
the roc ker anns.
d. Wiggle all four rock er arm s, the re should be
free play indicating that all four valves are
closed . T his ind icates that the piston is at top
dead ce nte r (T DC) on the comp ression stroke
and a ll fo ur val ves are c losed.
c. Chec k that the tlywheel timing mark is
aligned w ith the center line mark in the timing
inspection hole (F ig ure 80 ) in the recoil
starter co ve r.
8. Insert metric feeler gauges of vario us thick -
nesses between the rocker ann adj ust screw and in-
ta ke va lve ste m CA, F ig u re 81).
a. Wh en the correct gauge is se lecte d, there will
be a slight resistan ce on the feeler gauge
w hen
it
is inserted and wi thdrawn.
b. Reco rd the c learance and identify the valve
checked (right or left intake valve),
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