Vespa GTS Super 300 ie - Service manual > Removing the intake manifold

Loosen the 3 screws and remove the air intake manifold.

• Upon refitting, secure to the specified torque.

Removing the rocker-arms cover

• Remove the 5 screws indicated in the figure

Removing the timing system drive

• First remove the parts listed below: transmission cover, drive pulley with belt, oil sump with spring and by-pass piston, oil pump pulley cover, O-ring on the crankshaft and the sprocket wheel separation washer.
• Remove the tappet cover.
• Remove the central screw fastener and the automatic valve-lifter retaining cover, as shown in the figure.

• Remove the return spring of the automatic valve lifter unit and the automatic valve lifter unit and its end of stroke washer.

• Loosen the central screw on the tensioner first.
• Remove the two fixings shown in the figure.
• Remove the tensioner with its gasket.

• Remove the internal hex screw and the counterweight shown in the figure.

• Remove the camshaft control pulley with its washer.

• Remove the control sprocket wheel and the timing chain.
• Remove the screws indicated in the figure, the spacer bar and the tensioner slider.

  The chain tensioner slider must be removed from the transmission side. As regards the lower chain guide slider, it may only be removed after the head has been removed.

N.B.

IT IS ADVISABLE TO MARK THE CHAIN IN ORDER TO ENSURE THAT THE INITIAL DIRECTION OF ROTATION IS MAINTAINED.

Removing the cam shaft

• Remove the 2 screws and the camshaft retainer shown in the diagram.
• Remove the camshaft.
• Remove the pins and the rocking levers from the flywheel side holes.

N.B.

IF NEEDED, THE HEAD MAY BE REMOVED WITH THE CAMSHAFT, ROCKER PINS AND FIXING BRACKET. THE HEAD CAN ALSO BE REMOVED WITHOUT REMOVING THE CHAIN AND THE CRANKSHAFT CHAIN TENSIONER.

Removing the cylinder head

• Remove the spark plug.
• Remove the 2 side fixings shown in the figure.
• Loosen the 4 head-cylinder fastening nuts in two or three stages and in criss-cross fashion.
• Remove the head, the two alignment dowels and the gasket.

N.B.

IF NEEDED, THE HEAD MAY BE REMOVED WITH THE CAMSHAFT, ROCKER PINS AND FIXING BRACKET. THE HEAD CAN ALSO BE REMOVED WITHOUT REMOVING THE CHAIN AND THE CRANKSHAFT CHAIN TENSIONER.

Removing the valves

• Using the appropriate tool fitted with an adaptor, remove the cotters, caps, springs and valves.
• Remove the oil guards with the appropriate tool.
• Remove the lower spring supports.

CAUTION

REPLACE THE VALVES IN SUCH A WAY AS TO RECOGNISE THEIR ORIGINAL POSITION ON THE HEAD.

Specific tooling
  020382Y011 adapter for valve removal tool
  020382Y Valve cotters equipped with part 012 removal tool
  020431Y Valve oil seal extractor

Removing the cylinder - piston assy.

Removing cylinder and piston

• Remove the chain guide slider.
• Remove the 4 O-rings on the stud bolts.
• Pull out the cylinder.
• Remove the cylinder base gasket.
• Remove the two stop rings, the wrist pin and the piston.
• Remove the piston seals.

CAUTION

TO AVOID DAMAGING THE PISTON, SUPPORT IT WHILE REMOVING THE CYLINDER.

N.B.

BE CAREFUL NOT TO DAMAGE THE SEALING RINGS DURING REMOVAL.

Inspecting the small end

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Inspecting the wrist pin

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Inspecting the piston

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Inspecting the cylinder

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Inspecting the piston rings

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Removing the piston

• Install piston and wrist pin onto the connecting rod, aligning the piston arrow the arrow facing towards the exhaust.
• Fit the wrist pin retainer ring onto the appropriate tool
• With opening in the position indicated on the tool
  S = left
  D= right
• Place the wrist pin retainer ring into position using a punch
• Fit the wrist pin snap ring using the plug as shown in the figure

N.B.

THE TOOL FOR INSTALLING THE RETAINER RINGS MUST BE USED MANUALLY.

CAUTION

USING A HAMMER MIGHT DAMAGE THE STOPS' HOUSING.

Specific tooling
  020454Y Pin lock fitting tool

Choosing the gasket

• Provisionally fit the piston into the cylinder, without any base gasket.
• Assemble a dial gauge on the specific tool.

Specific tooling
  020428Y Piston position check mounting

• Using an abutment plane, reset the dial gauge with a preload of a few millimetres.
• Finally fix the dial gauge.
• Check the perfect sliding of the feeler pin.
• Install the tool on the cylinder without changing the dial gauge position.
• Lock the tool using the original head fixing nuts.
• Rotate the crankshaft up to the TDC (the inversion point of the dial gauge rotation)
• Measure the deviation from the reset value.

• By means of the table, see the Specifications chapter identify the cylinder base gasket thickness to be used for refitting. Correctly identify the cylinder base gasket thickness to keep the correct compression ratio.
• Remove the special tool and the cylinder.

N.B.

IF DEVIATIONS (OR RECESSES OR PROJECTIONS) CLOSE TO THE CHANGE OF CATEGORY ARE MEASURED, REPEAT THE MEASUREMENT AT THE OPPOSED SIDE. TO DO SO, REPEAT THE TOOL INSTALLATION BY INVERTING ITS POSITION.

Refitting the piston rings

• Place the scraper ring spring on the piston.
• Install the scraper ring keeping the opening opposed to the spring junction and with the writing "top" facing the piston crown. The chamfered side of the oil scraper ring should always be facing the piston crown.
• Fit the second lining with the identification letter or the writing "top" facing the piston crown. In any case, the step must be facing opposite the piston crown.
• Install the first compression lining in the direction imposed by the housing.
• It is advisable to use a fitter to facilitate the installation of the linings.

N.B.

THE TWO PISTON RINGS ARE MADE WITH A TAPERED CYLINDRICAL CONTACT CROSS-SECTION. THIS IS TO ACHIEVE A BETTER BEDDING.

• Misalign the lining openings at 120º as shown in the figure.
• Lubricate the components with engine oil.
• The engine uses the first compression lining with an L section.

Refitting the cylinder

• Insert the cylinder base gasket with the thickness determined above.
• Using the fork support and the piston ring retaining band, refit the cylinder as shown in the figure.

N.B.

BEFORE FITTING THE CYLINDER, CAREFULLY BLOW OUT THE LUBRICATION DUCT AND OIL THE CYLINDER LINER.

Specific tooling
  020426Y Piston fitting fork
  020393Y Piston assembly band

Inspecting the cylinder head

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Inspecting the timing system components

• Check that the guide slider and the tensioner slider are not worn out.
• Ensure that the camshaft control pulley chain assembly and the sprocket wheel are not worn.
• If you detect wear, replace the parts or, if the chain, sprocket wheel and pulley are worn, replace the whole unit.
•  Remove the centre screw with the washer and the tensioner spring. Check that the one-way mechanism is not worn.
• Check the condition of the tensioner spring.
• If examples of wear are found, replace the whole unit.

Inspecting the valve sealings

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

Inspecting the valves

N.B.

TO MEASURE WEAR LIMITS AND COUPLING CLEARANCES, SEE THE SPECIFICATIONS CHAPTER.

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