Dnepr MT10-36 - Valve Adjustment; Care of Valve Timing Gear

The exha ust va lve ope ns 50° before the pist on reach es th e bott om
dead centre, and clos ~s 10 ° aft er the piston passes the upper dead
ce ntre whi-ch is exhaust c losing lag. The ~xhaust duration is also
240°.
The above timing va lues are giv:en for the theoretical clearance
be t ween the va l ve stem and the rocker end equal to 2 ~~· .
Tlh e corre ct va lve bmmg IS ensu-
red by matching, during assemb lin g,
the marks on tim i ng pinions 2
(Fig . 9) and 4.
Valve Adjustment
Th e no rmal ope r ation of th e en -
gine depends to a gr eat extent on
the size of the expansion clearance
betwe en the valve stem and the
rocker end .
Wh en checking or adjusting th e
clearance, pla ce a tray under the
cylin der head, remove the cylinder
head cover
and drain the oil that has
accumulated. Set i:he piston to the
Fig. s. Valve timing diagram upper dead centne of the com-
pression stroke,
turn the crank-
shaft so that the mark "B" on the flywheel is matched with the mar k
on the crankcase. In doing so, observe through a sight hole in the
crankcase, after first removing the rubber p lug . In this position,
the both va lves will be completely clo se d, whereas their rockers
must fr ee ly sw ing on their pins. Then, using a flat feeler gauge,
check the clearance betw .een the both · rockers and the valves.
If the clearance is found to be incorrect, slacken ·check nut 24
(Fig . 7) and, by rotating adjusting bolt 23 in one direction or the
other, obtain the required clearance . This done, tighten up the check
nut. Th e clearance is adjusted on a cold eng ine and must be equal
to 0.07 mm . If the clearance is ab sent or too small, the valve wi ll
not fit closely to its seat at the moment of closing ; if the clearance
is too l· arge, the valve opening will be delayed.
The clea ran ce value should be ·checked whenever requi red when
check ing the clearance in the other cylinder turn the cr ankshaft
throug h 360° an d pro ceed with checki ng an d adjusting as it is des-
cribed above.
C are of Valve Tim ing Gear
In case knocking of the valves in creases , check and a dju st the
clea ran ces between the va l ve stem (cap) and the rocker end.
It must be borne in mind that on the air-cooled e ngine the ope-
ration of valve gear drive is we ll audible owing to the a bsen ce of a
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