Combustion Chambers - Yanmar YM155d Service Manual

NOTES:
( I )
Measure the inner diameter of the valve guides after they have been fitted
into position A press must be used to press-fir the valveguides into position when they
are replaced
If there
is
insufficient clearance between the valve guides and the valve stems, clearance
should be increased to rhe prescribed dimension by usinga reamer.
Before the intake
&
exhrmst valves are installed, coat the valve stems with lub oil.
(2) The width of the valve sears i s measured by a pair ofcalipers, and if corrections are
necessq, the prescribed valve curter must be used.
Ouzer diameter of volve:
Inzoke (3233.1) 1.0590-1.0669
Exhausr (2 7iU.1) 1.2559-1.263 7
After the valve seats have been dressed using the seat cutters, the valves are lapped.
i) Lapping should be done by using valve lapping compound powder.
ii) The finishing of the seat should be done by oil lapping.
iii) When fitting the valves back in position, do nor mix up the valves for No. I cyl-
inder with those of the No. 2 cylinder. All valves are marked prior to shipment
from the factow whether they are intake or exhaust valves,' and also whether
they are for the No. 1 or No. 2 cylinders.
ICI
IB)
15' cuner
(CI
65-75Ocl;trer
Seat width 0.0696 in.
(1.77
mml
Valve seat cuner
9. COMBUSTION CHAMBERS
n
(1) Visual Inspection
The combustion chambers consist of Yanmar's
patented special swirl type pre-combustion cham- Check the combustion chambers to see that the
bers. They improve combution performance and injection ports are not clogged or that carbon de-
contribute to achieving low fuel consumption. posits have not formed.