6 - cylinde… · web viewusing the feeler gauge, check the valve ... push the taper side of the...

CYLINDER AND HEAD)GENERAL

Components which are identical for both cylinders and cylinder heads are identified in the following two diagrams by the same number. Components which are different or which are, for instance, present either the cylinder OR the cylinder head, have different numbers. The information given below relates as a general rule.

Special reference is made in the text to work instructions, which are not the same for cylinder no. 1 and cylinder no. 2.

When diagnosing an engine problem, always perform a Cylinder Leak Test. This will help pinpoint a problem. Refer to the instructions included with your leak tester and to the LEAK TEST section for procedures.

Always place the vehicle on a level surface. For a better understanding, the many illustrations are taken with the

engine out of the vehicle. To perform the following instructions, it is not necessary to remove the engine from vehicle.

Always disconnect the BLACK (-) cable from the battery, then RED (+) the cable before working on the engine.

Even if the removal of many parts is not necessary to reach another part, it is recommended to remove these parts in order to check them.

During assembly/installation, use the torque values and service products as in the exploded views.

Clean threads before applying a threadlocker. Refer to SELF-LOCKING FASTENERS and LOCTITE APPLICATION at the beginning of this manual for complete procedure.

When disassembling parts that are duplicated in the engine, (e.g.: valves), it is a strongly recommended to note their position (PTO/MAG

side, front/rear cylinder) and keep them as a “group”. If you find a defective component, it will be much easier to find the cause of the failure among a group of parts. (For example, if you found a worn valve guide, a bent spring could be the cause and it’s easier to determine which when you group them at disassembly.) Also, since used parts have matched together during the engine operation, they will keep their matched fit when you reassemble them together within their “group”.

Caution: Torque wrench tightening specifications must strictly be adhered to. Locking devices (e.g.: locking tabs, elastic stop nuts, self-locking fasteners, cotter pin, etc.) must be installed or replaced with new ones where specified. If the efficiency of a locking device is impaired, it must be repaired.

VALVE ADJUSTMENTCAUTION: Check and adjust valve clearance only when engine is cold.

1. Remove the valve covers.2. Before checking or adjusting the valve clearance, turn the crankshaft

to TDC ignition of the respective cylinder. (See CAMSHAFT.)3. Using the feeler gauge, check the valve clearance.

Valve ClearanceExhaust 0.11 to 0.19 mmIntake 0.06 to 0.14 mm

If the valve clearance is out of specification, adjust valves as follows.NOTE : Use the mean valve clearance of the exhaust/intake to ensure a proper valve adjustment.

4. Hold the adjustment screw at the proper position and torque the locking nut.

5. Repeat the procedure for each valve.6. Before installing valve covers, recheck the valve clearance.

VALVE COVER

VAVLE Cover Removal1. Remove:

Distance screws of the valve cover

1 – Distance screws2 – Valve cover

Valve cover and gasket

1 – Valve cover2 – Gasket

2. Repeat the procedure for the other valve cover if required.

Valve Cover InspectionCheck the gasket on the valve cover. If it is brittle, cracked or hard, replace the gasket.

Valve Cover InstallationFor installation, reverse the removal procedure.Torque the valve cover distance screws in a criss-cross sequence.

TIMING CHAIN TENSIONERNOTE : Before removal and installation, make sure that the respective cylinder is set to TDC ignition. Refer to CAMSHAFT.

Timing Chain Tensioner RemovalCaution: The timing chain tensioner is spring-loaded. Never perform this operation immediately after the engine has been turned off because the exhaust system can be very hot. Wait until the exhaust system is warm or cold.

1. Remove: Chain tensioner plug O-ring Spring Chain tensioner plunger

1 – Chain tensioner plug2 – O-ring3 – Spring4 – Chain tensioner plunger

Screws retaining chain tensioner housing Chain tensioner housing with O-ring

1 – Chain tensioner screws2 – Chain tensioner housing3 – O-ring

Timing Chain Tensioner Inspection1. Check the housing for cracks or other damages, and replace if

necessary2. Check the chain tensioner plunger for free movement and/or scoring.3. Check if the O-rings are brittle, cracked or hard, and replace if

necessary.4. Check the spring condition. Replace if broken or worn.

Timing Chain Tensioner Installation

For installation, reverse the removal procedure. However, pay attention to the following:

Before installing the chain tensioner make sure, that the camshaft timing gear can be moved back and forth.

MOVE GEAR BACK AND FORTH Apply engine oil on the plunger before installing.

NOTE : Slightly screw in the plunger until the timing chain allows no more back and forth movement of the camshaft timing gear. Then screw in the plunger an additional 1/8 turn to reach the required torque of 0.1 N/m.CAUTION : Improper adjustment of the timing chain will lead to severe engine damage.

Fit the spring on one side into the slot of the plug screw and on the other side into the plunger. Turn spring only clockwise in order to fit the spring end into the notch of the plunger and to avoid loosening the plunger during spring installation. Do not preload the spring.NOTE : Do not forget to place the O-ring on the chain tensioner plug.

Then compress the spring and screw in the plug screw. Finally, tighten the plug screw to 4.5 N/m.

CAMSHAFT TIMING GEARCamshaft Timing Gear Removal

1. Remove the valve cover.2. Turn the crankshaft to TDC ignition of the respective cylinder. (Refer to

CAMSHAFT.)3. Unscrew the timing chain tensioner.4. Remove the camshaft timing gear screw.5. To prevent the timing chain stretching during the removal of the

camshaft timing gear screw, use the camshaft locking tool.

1 – Camshaft locking tool2 – Camshaft timing gear screw3 – Camshaft timing gear4 – Trigger wheel (cylinder head 1 only)

6. Remove the camshaft timing gear.NOTE : Secure the timing chain with a retaining wire.

Camshaft Timing Gear InspectionCheck the camshaft timing gear for wear, deterioration or damage. If gear is worn or damaged, replace both the camshaft timing gear and the timing chain.For crankshaft gear, refer to BOTTOM END and see CRANKSHAFT.

Camshaft Timing Gear InstallationFor installation, reverse the removal procedure.

1. Clean the mating surface and threads of camshaft, prior to assembling the camshaft timing gear.

1 – Mating surface on camshaft2 – Threads for camshaft screw

2. The camshaft timing gear and crankshaft must be at TDC ignition position before installing the timing chain.CAUTION: The crankshaft and camshaft must be locked on the TDC ignition position to place the camshaft timing gear and timing chain in the proper position.

3. Install the camshaft timing gear so that the timing gear tabs are located on the flat zone of the camshaft.

4. The printed marks on the camshaft timing gear must be parallel to the cylinder head base. Refer to the following illustration for the proper positioning.

1 – Printed marks on the camshaft timing gear2 – Cylinder head base3 – Camshaft timing gear4 – Timing gear tab

5. Install the trigger wheel on the camshaft timing gear of cylinder 1.

1 – Camshaft locking tool2 – Camshaft screw3 – Camshaft timing gear4 – Trigger wheel (cylinder head 1 only)

6. When the camshaft timing gear and the timing chain are installed, remove the crankshaft locking bolt as well as the camshaft locking tool.NOTE : Before installing the camshaft screw, adjust the chain tension (refer to CHAIN TENSIONER) and ensure the marks on the timing gear are parallel to cylinder head base.

7. Reinstall all other removed parts.

ROCKER ARMRocker Arm Removal

1. Remove: Valve cover Chain tensioner Camshaft timing gear no. 1 Allen screw and camshaft retaining plate

1 – Cylinder head2 – Allen screw3 – Camshaft retaining plate

Rocker arm shafts Rocker arm assembly (exhaust side and intake side) with

adjustment screws and nuts

1 – Rocker arm shaft2 – Rocker arm (exhaust side)3 – Rocker arm (intake side)4 – Adjustment screw5 – Locking nut

Thrust washer no.2CAUTION : Pay attention not to lose thrust washers or drop them into the timing chain compartment.

Rocker Arm Inspection1. Inspect each rocker arm for cracks and scored friction surfaces. If so,

replace rocker arm assembly.2. Check the rocker arm rollers for free movement, wear and excessive

radial play. Replace rocker arm assembly if necessary.

1 – Rocker arm (exhaust side)2 – Roller3 – Bore for rocker arm shaft

3. Measure the rocker arm bore diameter. If diameter is out of specification, change the rocker arm assembly.

Rocker Arm Bore DiameterNew 12.036 to 12.050

mmService limit 12.60 mm

4. Check adjustment screws for free movement, cracks and/or excessive play.

1 – Free movement of adjustment screw top

Rocker Arm Shaft1. Check for scored friction surfaces, and replace parts if necessary.2. Measure rocker arm shaft diameter.

A – Measure rocker arm shaft diameter here

Rocker Arm Shaft Diameter New 12.000 to 12.018


Any area worn excessively will require parts replacement.

Rocker Arm InstallationNOTE : Use the same procedure for both the exhaust and intake rocker arm.

1. Apply engine oil on the rocker arm shaft.2. Install the rocker arm shafts with the chamfered edge first3. Insert a rocker arm pin through rocker arm pin bore.4. Install a thrust washer no. 2, and then the proper rocker arm no. 3

(exhaust side) or no. 4 (intake side).5. Push in the rocker arm shaft until its chamfer reaches the end of rocker

arm bore.

1 – Rocker arm shaft 2 – Thrust washer (timing chain side)3 – Thrust washer (spark plug side)

6. Place the other thrust washer and push the rocker arm shaft to the end position.

7. Install the camshaft retaining plate no. 5.

TIMING CHAINRefer to BOTTOM END, see TIMING CHAIN.

CYLINDER HEAD

Cylinder Head RemovalThe removal procedure is the same for both cylinder heads.

1. Drain the coolant. (Refer to COOLING SYSTEM.)NOTE: Before removing the cylinder head, blow out any remaining coolant with air pressure. During the cylinder head removal, the remaining coolant in the cylinder head could overflow into the engine and a small quantity of coolant could drop into the engine. If that happens, the engine oil will be contaminated.

2. Disconnect: Spark plug wire Temperature sensor connector, located at rear cylinder head Camshaft sensor, located at front cylinder head.

3. Remove: Both side panels and both inner fenders (Refer to BODY) Exhaust pipe spring Exhaust pipe nuts Radiator inlet hose Air filter box and throttle body Air intake manifold Chain tensioner (Refer to CHAIN TENSIONER) Valve cover and gasket (Refer to VALVE COVER) Camshaft timing gear Cylinder head screws M6 Cylinder head screws M10 retaining cylinder head and cylinder to

cylinder base.

1 – Cylinder head screws M102 – Cylinder head screws M6

4. Pull up cylinder head.5. Remove:

Chain guide Cylinder head gasket – and scrap it

1 – Cylinder head2 – Timing chain3 – Chain guide4 – Cylinder head gasket

Cylinder Head Inspection1. Inspect the timing chain guide for wear, cracks or other damages, and

replace if necessary.2. If there are cracks between the valve seats, replace the cylinder head.3. Check the mating surface between the cylinder and cylinder head for

contamination. If so, clean both surfaces.4. Clean the oil support through the cylinder head from contamination.

1 – Oil port to lubricate camshaft lobes intake/exhaust2 – Oil supply to camshaft bearing journal timing chain side3 – Oil supply to camshaft bearing journal spark plug side

Cylinder Head InstallationFor installation, reverse the removal procedure.

NOTE : The cylinder heads are not identical in design. Do not invert the cylinder heads at assembly.NOTE: Ensure the dowel pins no. 9 are in place.CAUTION: Chain guide must be fixed between cylinder and cylinder head.

1 – Chain guide (fixed between cylinder and cylinder head)2 – Chain tensioner guide (mounted in crankcase)

1. First, torque the cylinder head screws M10 in a criss-cross sequence to 20 N/m, then finish by tightening to 60 N/m.

2. Install cylinder head screws M6.

1 – Cylinder head screws M102 – Cylinder head screws M6

3. Check chain guide for movement.4. Remove crankshaft locking bolt and reinstall plug screw with sealing

ring.

CAMSHAFT

NOTE : The engine is equipped with two different camshafts.

1 – Camshaft of cylinder 12 – Camshaft of cylinder 2

Camshaft TimingNOTE : If a piston (of cylinder 1 or 2) is set to TDC ignition, the camshaft timing gear of the opposite cylinder must be in the following position.

1 – Marks on timing gear of the opposite cylinder2 – Cylinder head base

Camshaft Timing Cylinder 21. Turn crankshaft until piston is at TDC ignition as follows.2. Remove:

Spark plug cable and spark plug of both cylinders Valve cover of both cylinders Plug screw and O-ring of magneto cover

1 – Plug screw2 – O-ring

Crankshaft position sensor

1 – Crankshaft position sensor2 – Screw

3. Use a 14 mm Allen key to turn crankshaft until piston 2 (rear) is at TDC ignition.

1 – Allen key 14 mm

4. When rear piston is at TDC ignition, marks on magneto flywheel “2” and on the magneto cover are aligned.

1 – Mark “2” on magneto flywheel2 – Notch on magneto cover3 – Crankshaft position sensor location

5. At TDC ignition, the printed marks on the camshaft timing gear have to be parallel to the cylinder head base.

1 – Printed marks on camshaft timing gear2 – Cylinder head base

6. To lock crankshaft at TDC ignition, proceed as follows:

Remove from crankcase plug screw with sealing ring.

1 – Plug screw2 – Sealing ring3 – Crankcase PTO side, front side

Lock the crankshaft with the crankshaft locking bolt.

1 – Crankshaft locking boltNOTE: Make sure the locking bolt engines in the groove of the crankshaft.

Camshaft Timing Cylinder 11. Turn cylinder 2 to TDC ignition. (Refer to CAMSHAFT TIMING CYLINDER

2.)NOTE: Do not lock crankshaft.

2. Using a 14 mm Allen key, turn the crankshaft 280° counterclockwise, until the marks on magneto flywheel “1” and the magneto cover are aligned.

1 – Allen key 14mm2 – Turn crankshaft 280° counterclockwise

1 – Mark “1” on magneto flywheel2 – Notch on magneto cover3 – Location of the crankshaft position sensor

NOTE: At TDC ignition, the printed marks on the camshaft timing gear have to be parallel to cylinder head base as indicated in the following diagram.

1 – Printed marks on camshaft timing gear2 – Cylinder head baseCAUTION: Crankshaft cannot be locked at cylinder 1 TDC ignition.

Camshaft RemovalThe removal procedure is the same for both camshafts.Note: Each camshaft is different in design. Thus, it is important not to mix up any parts of the camshaft assembly with that of the other cylinder. Keep parts as a group.

1. Remove: Valve cover (Refer to VALVE COVER.) Chain tensioner (Refer to CHAIN TENSIONER.) Camshaft timing gear (Refer to CAMSHAFT TIMING GEAR.) Camshaft retaining plate

1 – Cylinder head2 – Allen screw3 – Camshaft retaining plate

Rocker arms (Refer to ROCKER ARM.) Camshaft

NOTE: For removal, rotate the camshaft so that intake/exhaust lobe shows to the upper side of the cylinder head.

Camshaft Inspection1. Check each lobe and bearing journal of the camshaft for scoring,

scuffing, cracks or other signs of wear.2. Measure the camshaft bearing journal’s diameter and the lobes’ height

using a micrometer.

A – Camshaft lobe (exhaust valves)B – Camshaft lobe (intake valves)C – Camshaft journal timing chain sideD – Camshaft journal spark plug side

V-490Camshaft lobe (Exhaust)New 31.730 to 31.930


Camshaft Lobe (Intake)New 31.830 to 32.030


V-660/V-810Camshaft Lobe (Exhaust)New 31.940 to 32.140


Camshaft Lobe (Intake)New 32.110 to 32.310


All EnginesCamshaft Journal

(Timing Chain Side)

New 34.959 to 34.975 mm

Service limit 34.950 mmCamshaft Journal(Spark Plug Side)

New 21.959 to 21.980 mm

Service limit 21.950 mm

3. Measure the clearance between both ends of the camshaft and cylinder head.

A – Cylinder head camshaft bearing timing chain sideB – Cylinder head camshaft bearing spark plug side

All EnginesCylinder Head Camshaft Bearing

(Timing Chain Side)

New 35.000 to 35.025 mm

Service limit 35.040 mmCylinder Head Camshaft Bearing

(Spark Plug Side)

New 22.000 to 22.021 mm

Service limit 22.040 mm

4. Replace parts that are not within specifications.

Camshaft InstallationFor installation, reverse the removal procedure. Pay attention to the following details.CAUTION: The camshafts are not identical in design. Do not invert the camshafts during assembly. Any mix-up of the components will lead to engine damage.

Place the camshaft retaining plate in the slot of the camshaft.

1 – Camshaft retaining plate position2 – Slot retaining camshaft 3 – Direction of movement

For other parts, refer to their specific installation procedures.

VALVE SPRINGValve Spring Removal

Caution: Always wear safety glasses when disassembling valve springs. Be careful when unlocking valves. Components could fly away because of the strong spring preload.

1. Remove: Rocker arms (Refer to ROCKER ARM.) Cylinder head (Refer to CYLINDER HEAD.)

2. Compress valve spring no. 6; use the valve spring compressor clamp and valve spring compressor cup.

3. Remove valve cotters.

1 – Valve spring compressor clamp2 – Valve spring compressor cup3 – Valve cotter

4. Withdraw the valve spring compressor, the valve spring retainer no. 7 and the valve spring no. 6.

Valve Spring Inspection1. Check the valve spring for visible damages. If so, replace the valve

spring.2. Check the valve spring for free length and straightness. Replace valve

springs if not within specifications.

A – Valve spring length

Valve Spring Free LengthNominal New 40.81 mmService Limit 39.00 mm

Valve Spring InstallationFor installation, reverse the removal procedure. Pay attention to the following details:

Colored area of the valve spring must be placed on top. To ease installation of the cotters, apply oil or grease on them so that

they remain in place while releasing the spring.NOTE : Valve cotter must be properly engaged in valve stem grooves.

After the spring is installed, ensure it is properly locked by tapping on the valve stem end with a soft hammer so that the valve opens and closes a few times.CAUTION : An improperly locked valve spring will cause engine damage.

VALVEVALVE Removal

1. Remove the valve spring. (Refer to VALVE SPRING.)2. Push the valve stem, and then pull valves (intake and exhaust) out of

valve guide.3. Remove the valve stem seal no. 8 with Snap-On pliers and discard it.

Valve Stem Seal InspectionAlways install new seals whenever valves are removed.Valve InspectionInspect valve surface, check for abnormal stem wear and bending. If out of specification, replace by a new one.

Valve Out of Found(intake and exhaust valves)

New 0.005 mmService limit 0.06 mm

Valve Stem and Valve Guide Clearance1. Measure the valve stem and valve guide in three places using a

micrometer and a small bore gauge.NOTE : Clean the valve guide to remove carbon deposits before measuring.

2. Change the valve if the valve stem is out of specification or has other damages, such as wear or friction surface.

Valve Stem DiameterExhaust Valve

New 4.956 to 4.970 mm

Service Limit 4.930 mmIntake Valve

New 4.966 to 4.980 mm

Service Limit 4.930 mm

3. Replace the valve guide out of the cylinder head if the valve guide is out of specifications, or has other damages such as wear or friction surface. (Refer to VALVE GUIDE PROCEDURE.)

Valve Guide Diameter(Intake and Exhaust Valves)

New 5.006 to 5.018 mm


Valve Face and Seat

1. Check the valve face and seat for burning or pitting. Replace the valve or cylinder head if there are signs of damage.

2. Ensure to seat the valve properly. Apply some lapping compound to the valve face and work the valve on its seat with a lapping tool. (Refer to VALVE GUIDE PROCEDURE.)

3. Measure the valve face contact width.NOTE : The location of contact area should be in center of valve seat.

4. Measure valve seat width using a caliper.

Valve Seat Contact WidthExhaust Valve

New 1.25 to 1.55 mmService Limit 2.00 mm

Intake ValveNew 1.05 to 1.35 mm

Service Limit 1.80 mm5. If the valve seat contact width is too wide or has dark spots, replace

the cylinder head.

Valve InstallationFor installation, reverse the removal procedure. Pay attention to the following details:

Install a NEW valve stem seal. Make sure the thrust washer is installed before installing the seal.

Apply engine oil on the valve stem and install it.CAUTION: Be careful when the valve stem is passed through the sealing lips of the valve stem seal.

To ease installation of the cotters, apply oil or grease on them so that they remain in place while releasing the spring.

After spring is installed, ensure it is properly locked by tapping on the valve stem end with a soft hammer so that valve opens and closes a few times.CAUTION : An improperly locked valve spring will cause engine damage.

VALVE GUIDE

Valve Guide RemovalNOTE : Clean valve guide area from contamination before removal. Using valve guide remover, remove the valve guide with a hammer.

1. Remove: Cylinder head (Refer to CYLINDER HEAD.) Valve spring (Refer to VALVE SPRING.) Valves (Refer to VALVE.)

Valve Guide InstallationAlways replace the valve stem seals whenever procedure (POSSIBLE??).Pay attention to the following details:

Use the valve guide installer to install the valve guide.NOTE : Apply Loctite 767 (antiseize lubricant) on the valve guide prior to installing it into the cylinder head.

CAUTION : Push valve guide in the cold cylinder head as per following illustration.

Valve Guide(Measurement “A”)

New 14.00 to 14.40 mm

The valve guide is to be adjusted in diameter by using a reamer.

Valve Guide Diameter(Intake and Exhaust Valves)

New 5.006 to 5.018 mm

NOTE : Ensure to turn the reamer in the correct direction.

Using cutting oil and make brakes to clean reamer/valve guide from metal shavings. Apply some lapping compound to the valve face and work the valve on its seat with a lapping tool.NOTE : Ensure to seat the valves properly. Apply marking paste to ease checking contact pattern.

Repeat the procedure until the valve seat and valve face fit together.

CYLINDER Cylinder Removal

1. Remove: Chain tensioner (Refer to CHAIN TENSIONER.) Camshaft timing gear (Refer to CAMSHAFT TIMING GEAR.) Cylinder head (Refer to CYLINDER HEAD.)

2. Pull the cylinder.3. Discard the cylinder base gaskets.

Cylinder InspectionCheck the cylinder for cracks, scoring and wear ridges on the top and bottom of the cylinder. If so, replace the cylinder.

Cylinder Taper

1. Measure the cylinder bore and if it is out of specifications, replace the cylinder and the piston rings.

2. Measure the cylinder bore at three recommended positions. See the following illustration.

Cylinder Taper in DiameterNew

(Maximum) 0.038 mmService Limit 0.090 mm

The distance between the measurements should not exceed the service limit mentioned above.

Cylinder Out of Round1. Measure the cylinder diameter in the piston axis from the top of the

cylinder.2. Take another measurement 90° from first one and compare.NOTE: Take the same measuring points like described in CYLINDER TAPER above.

Cylinder Out of RoundNew

(Maximum) 0.015 mmService Limit 0.020 mm

Cylinder InstallationFor installation, reverse the removal procedure. Pay attention to the following details:CAUTION : Always replace cylinder base gasket before installing the cylinder.

1. Mount cylinder 2. 2. Remove the crankshaft locking bolt. 3. Crank the engine further, and position piston 1 at TDC. 4. Mount cylinder 1. The cylinder cannot be pushed fully over the piston

unless the piston is located at TDC.5. Apply engine oil in the bottom area of the cylinder bore and also on the

band of the piston ring compressor tool.NOTE : Put the timing chain through the chain pit, and then put the cylinder in place.

6. CAUTION: The chain guide has to be fixed between the cylinder and the cylinder head.NOTE: After both cylinders are installed, turn the crankshaft until the piston of cylinder 2 is at TDC ignition, and then lock the crankshaft. (Refer to CAMSHAFT.)

7. Install the cylinder head and the other parts in accordance with the proper installation procedures.

PISTONPiston Removal

1. Remove: Cylinder head (see CYLINDER HEAD.) Cylinder (see CYLINDER.)

2. Place a rag under piston and in the area of timing chain compartment.Caution: Piston circlips are spring loaded.

3. Remove one piston circlip and discard it.NOTE: The removal of both piston circlips is not necessary to remove the piston pin.

4. Push piston pin out of piston.5. Detach piston from connecting rod.

Piston Inspection1. Inspect piston for scoring, cracking or other damages. Replace piston

and piston rings if necessary.2. Using a micrometer, measure piston at 8 mm perpendicularly (90°) to

piston pin.3. The measured dimension should be as described in the following table.

If not, replace piston.

Piston MeasurementV-490/V-660

New 81.950 to 81.966 mm

Service Limit 81.850 mmV-810

New 90.950 to 90.966 mm

Service Limit 90.850

Piston/Cylinder Clearance1. Adjust and lock a micrometer to the piston dimension 2. With the micrometer set to the dimension, adjust a cylinder bore gauge

to the micrometer dimension and set the indicator to 0 (zero).3. Piston the dial bore gauge 20 mm above cylinder base, measuring

perpendicularly (90°) to piston pin axis.4. Read the measurement on the cylinder bore gauge. The result is the

exact piston/cylinder wall clearance.

Piston/Cylinder ClearanceV-490/V-660

New 0.057 to 0.087 mm

Service limit 0.130 mmV-810

New 0.027 to 0.057 mm

Service limit 0.100 mmNOTE: Make sure used piston is not worn.

5. If clearance exceeds specified tolerance , replace piston by a new one and measure piston/cylinder clearance again.NOTE: Make sure the cylinder bore gauge indicator is set exactly at the same position as the micrometer, otherwise the reading will be false.

Connecting Rod/Piston Pin Clearance1. Using synthetic abrasive woven, clean piston pin from deposits Inspect

piston pin for scoring, cracking or other damages.2. Measure the piston pin. See the following table for the proper

measurement positions.Piston Pin Diameter

V-490New 17.996 to 18.000

mmService Limit 17.980 mm

V-660/V-810New 19.996 to 20.000


3. Replace piston pin if diameter is out of specifications.4. Measure the inside diameter of the connecting rod small end bushing.

5. Replace the connecting rod if the diameter of the connecting rod small end is out of specifications. (Refer to BOTTOM END for removal procedure.)

6. Compare measurements to obtain the connecting rod/piston pin

Connecting Rod Small End Diameter

V-490New 18.010 to 18.020


V-660/V-810New 20.010 to 20.020


clearance.

Connecting Rod/Piston Pin ClearanceAll Engines


Piston InstallationFor installation, reverse the removal procedure. Pay attention to the following details.

1. Apply engine oil on the piston pin.2. Insert piston pin into piston and connecting rod.

CAUTION : The mounting direction of the pistons is different between the V-490/V-660 and the V-810.

V-490 and V-660 Engines CAUTION : Take care that pistons will be installed with the

punched arrow on piston top direction to the exhaust side of the respective cylinder.

Front cylinder: the mark on the top of the piston must show to the exhaust side.

Rear cylinder: the mark on the top of the piston must show to the exhaust side.

V-810 Engines CAUTION : Take care that pistons will be installed with the

punched arrow on piston top direction to the rear side of the engine.

Front cylinder: The mark on the top of the piston must show to the intake side.

Rear cylinder: The mark on the top of the piston must show to the exhaust side.

3. Use the piston appropriate circlip installer to assemble the new piston circlip as per the following procedure:CAUTION : Always replace disassembled piston circlip(s) by new ones. Place a rag on cylinder base to avoid dropping the circlip inside the engine.

a. Place the circlip in the sleeve.b. Push the taper side of the assembly jig until circlip reaches the

middle of the sleeve.c. Align the sleeve with the piston pin axis and push the assembly

jig until the circlip engages in piston.NOTE: Take care that the hook of the piston circlip is positioned properly.

PISTON RINGS

Piston Ring Removal1. Remove:

Cylinder head Cylinder Piston pin

Piston Ring/Piston Groove ClearanceUsing a feeler gauge, measure each ring/piston’s groove clearance. If the clearance is too large, the piston and the piston rings should be replaced.

Ring/Piston Groove ClearanceUpper Compression Ring

New 0.030 to 0.070 mm

Service Limit 0.150 mmLower Compression Ring

New 0.020 to 0.060 mm

Service Limit 0.150 mmOil Scraper Ring

New 0.010 to 0.045 mm


Piston Ring/End Gap Clearance1. To measure the ring end gap, place the ring in the cylinder in the area

of 8 to 16 mm from top of cylinder.NOTE : In order to correctly position the ring in the cylinder, use piston as a pusher.

2. Using a feeler gauge, check ring end gap. Replace ring if gap exceeds above described specified tolerance.

Ring End GapUpper Compression Ring


Lower Compression RingNew 0.20 to 0.40 mm

Service Limit 1.50 mmOil Scraper Ring


Piston Ring InstallationFor installation, reverse the removal procedure. Pay attention to the following details.

NOTE: First, install the spring and then the rings of the oil scraper ring. Install the oil scraper ring first, then the lower compression ring with the word “N and TOP” facing upward, then the upper compression ring with the word “N and TOP” facing upward.CAUTION: Ensure that top and second rings are not interchanged.

NOTE: Use a ring expander to prevent breakage during installation. The oil ring must be installed by hand.

Check that the rings rotate smoothly after installation. Space the piston ring end gaps 120 apart and do not align the gaps with the piston pin bore or the thrust side axis.

6 - cylinde… · web viewusing the feeler gauge, check the valve ... push the taper side of the...

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