Suzuki: Engine K6A-YH6. Service manual - part 8

 

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Suzuki: Engine K6A-YH6. Service manual - part 8

 

 

THEORY OF OPERATION

4-9

4

4.5 Cylinder Head and Valve Train

See Figure 4-10.

Figure 4-10

The twin cam, 4-valve per cylinder head is constructed 
with an aluminum alloy that is both lightweight and 
efficient in heat dissipation. Valve angle is set narrow to 
also make for a compact head design.

The spark plug port (12) is located in the center of the 
combustion chamber, with the combustion chamber 
being a pent-roof design for improved combustion 
efficiency.

The intake (11) and exhaust ports (13) are arranged in a 
cross-flow style with each cylinder having two intake and 
two exhaust valves for improved intake and exhaust 
efficiency. Intake valves are faced with a dual angle while 
exhaust valves have a single angle face.

The valve spring retainer (5), valve spring (6), valve seal 
(7), and valve spring seat (8) are all installed over the 
valve stem and held in place with the retainer locks (4). 

The valves (9 and 10) are pushed down directly with the 
camshaft lobe (1) via shim (2) and tappet (3). Valve lash 
is adjusted by varying the thickness of the shim (2).

1

Camshaft Lobe

6

Valve Spring

11

Intake Port

2

Shim

7

Valve Seal

12

Spark Plug Port

3

Tappet

8

Valve Spring Seat

13

Exhaust Port

4

Retainer Lock

9

Intake Valve

5

Valve Spring Retainer

10

Exhaust Valve

TN0750, 0523, 0493

1

2

3

6

7

8

9

4

13

12

11

10

5

4-10

THEORY OF OPERATION

4

Head Gasket

See Figure 4-11.

Figure 4-11

The cylinder head gasket is made of a 2-layer laminated 
stainless steel. The surface of the cylinder head gasket is 
treated with a rubberized coating.

Camshaft

See Figure 4-12.

Figure 4-12

The intake (1) and exhaust (2) camshafts are made of 
lightweight hollow cast iron. The camshaft timing 
sprockets (3) are press fit onto the front of the camshafts 
and are serviceable only with the camshaft. Engine oil 
flows through the hollow center of the cams, direct 
lubricating the camshaft journals. Camshaft lobes, 
tappets, and valves are indirect splash lubricated from 
the camshaft journals.

TN0494

TN0505

1

2

3

THEORY OF OPERATION

4-11

4

4.6 Lubrication System

See Figure 4-13.

Figure 4-13

The K6A engine uses a wet sump lubrication system, 
which force feeds oil through the full-flow oil filter and the 
entire lubrication system.

The inner rotor of the oil pump is driven by the 
crankshaft. The outer rotor is driven with the inner rotor. 
The pump creates suction, and draws oil through the oil 
pickup strainer from the oil pan. The oil is pumped 
through the main passage of the front cover into the 
engine block and the oil filter.

An oil pressure switch is located in this passage to 
monitor and warn of low oil pressure.

The oil is routed through a full-flow oil filter equipped with 
a bypass valve. The bypass valve will open and allow oil 
flow to the engine in the event the filter becomes plugged 
or damaged and will not allow oil flow to the engine. From 
the filter, the oil flows into the main gallery. The main 
gallery sends oil to both the cylinder block and the 
cylinder head.

OIL PRESSURE

SWITCH

BYPASS VALVE

LUBE OIL FILTER

CYLINDER BLOCK  MAIN GALLERY

.

REGULATOR

VALVE

LUBE OIL PUMP

OIL SUCTION PIPE

(STRAINER)

TENSION

ADJUSTER

TIMING

CHAIN

FRONT CAM

JOURNAL

CAMSHAFT

CAM JOURNALS

CAM FACE

TAPPETS,

PISTON PIN

CONNECTING

ROD

ROD

JOURNALS

ROD PIN

CRANK PIN

CRANK

JOURNALS

OIL PAN

VALVES

TN0751

4-12

THEORY OF OPERATION

4

From the main gallery, oil distributes to the crankshaft 
journals and crank pins. The crankshaft is drilled 
between the crank pins and rod pins. Oil flows through to 
the rod pins, lubricating the rod journals, and then passes 
into a drilled passage in the connecting rod. Oil also 
seeps out the sides of the crank and rod journals to 
lubricate the sides of the journals. Any excess oil from 
lubricating the crank and rod journals passes out from 
the journals and returns to the oil pan.

The passage in the connecting rod leads to an oil jet at 
the top of the large end of the rod.This jet sprays oil 
upward to lubricate the cylinder walls, piston, and piston 
pin. Excess oil drains back to the oil pan.

Oil from the main gallery is also sent up to the cylinder 
head. On its way up to the cylinder head, the oil passes 
through a restrictor orifice. This limits the amount of oil to 
the head and ensures the proper amount of oil in the 
lower end of the engine.

When the oil reaches the cylinder head, the passage 
splits. Oil is sent to the timing chain tension adjuster to 
maintain proper chain tension. An orifice in the tension 
adjuster also provides a spray to lubricate the timing 
chain.

The oil is also sent up to the front of the cylinder head, 
where it lubricates both of the front camshaft journals. Oil 
enters both camshafts from the front journals and flows 
through the camshafts, where it exits lube holes for each 
of the other camshaft journals. Excess oil exits the 
journals and splash lubricates the camshaft faces and 
tappets. Oil seeps through oil holes in the tappet 
adjusting shims and tappets to lubricate the valves.

Excess oil then flows through return passages from the 
cylinder head and returns to the oil pan.

 

 

 

 

 

 

 

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