Suzuki DR350 Service Manual page 51

NO TE!
The valve sea t con tact area must be inspected after each
cut.
1 I nsert with a slight rotation, the solid pilot that g ives a
.
snug fit. The shoulder on the p ilot shou ld be about 1 0
mm ( 0 . 3 9 i n ) from the valve guide.
2 . Using the 4 5 0 c utter, descale and cleanup the seat with
one or two turn s .
3 . I nspect the seat b y the previous seat width measurement
procedure. If the seat i s pitted or burne d , a d d itio n a l seat
conditioning with the 4 5 0 cutter is req u i re d .
CAUTION:
Cut the minimum amount necessary from the seat to pre­
vent the possibility of the valve stem becoming too close
to the rocker arm for correct valve contact angle.
If the contact a rea i s too low or too n arrow, use the 4 5 0
cutter to raise a n d widen the contact area . I f the contact
a rea is too high or too wide, use the 1 5 0 cutter to lower
and narrow the contact area.
4 . After the desired seat positon and width is achieved , use
the 450 cutter very l ig htly to clean u p a ny b u rrs c aused
by the previous cutting o perations. DO NOT use l a pping
compound after the final cut is made . The finished valve
seat should h ave a velvety smooth finish a n d not a high­
ly polished or shiny fin i s h . This will provide a soft sur­
face for the fina l seating of the valve which will occur
during the first few seconds of engine operati o n .
5 . Clean a n d assemb l e t h e head a n d valve components. Fill
the intake and exhaust ports with gasoline to check for
leaks. If any leaks occur, i nspect the valve seat and face
for burrs or other things that could prevent the valve from
sealing .
WARNING :
to
Always use extreme caution when handling gasoline.
NO TE:
Be sure ad just the valve clearance after reassembling the
engine.
VALVE STE M E N D C O N DITION
Inspec the valve stem end face for pitting a n d wear. If pit­
ting or wear of the stem end face are present, the valve stem
end may be resu rfaced , providing that the length
be reduced to less than 1 . 8 mm ( 0 . 0 7 in ) . If this l ength be-
. comes less than 1 . 8 m m (0.07 i n ) , the valve m u st be
replaced . After insta l l i ng a valve whose stem end has been
g round off as a bove, check to ensure that the face @ of
the valve stem end is a bove the cotters @ .
Contact area too low
a n d too narrow on face
of valve
Contact area too high
a n d too wide o n face of
valve
CD
will not
ENGINE
3·20