Checking the piston (Aprilia Shiver 750)

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Measure the piston skirt diameter "P" with a micrometer (a=10 mm (0.39 in) from the piston lower border).

Calculate the clearance between piston and cylinder as follows:

• Piston - cylinder clearance C = C - P
• Piston - cylinder clearance: 0.050 - 0.064 mm (0.00197 - 0.00252 in)
• Limit: 0.100 mm (0.00039 in)

Replace the cylinder, the piston and the piston ring all together if not complying with specifications.

Piston rings

Clean off any carbon deposits from the grooves in the piston rings and from the rings themselves.

Measure the piston ring side clearance and replace the piston and the piston rings all together if not complying with specifications.



Piston ring side clearance:

• Top ring (1st slot): 0.030 - 0.065 mm (0.0012 - 0.0026 in)
• Intermediate ring (2nd slot): 0.020 - 0.055 mm (0.0008 - 0.0022 in)
• Oil scraper ring (3rd slot): 0.010 - 0.045 mm (0.0004 - 0.0018 in)

Fit the piston ring to the cylinder.


Level the installed piston ring with the piston crown.

Measure piston ring port and replace it if not complying with specifications.

Caution! It is not possible to measure the gap of the oil scraper ring end: if clearance is excessive, replace the three piston rings.

Piston ring end gap:

• Top ring: 0.25 - 0.40 mm (0.0079 - 0.0157 in)
• Intermediate ring: 0.35 - 0.55 mm (0.0138 - 0.0216 in)
• Oil scraper ring: 0.20 - 0.70 mm (0.0079 - 0.0276 in)

Pin

Clean off combustion residues from the piston crown and from the area above the top ring.

Check for cracks on the piston and for compression on the piston sliding surface (seizing); Replace the piston if required.

Caution! Small striations on the piston liner are admissible.

Measure the pin outside diameter (a) and if not complying with specifications, replace the pin.

Pin outside diameter: 22.00 - 21.97 mm (0.8661 - 0.8650 in)

Limit: 21.96 mm (0.8646 in)



Measure the pin housing diameter (b) and replace the piston if not complying with specifications.


Pin housing diameter (b): 22.010 - 22.015 mm (0.8665 - 0.8667 in)



Calculate the clearance between pin and pin hole and, if not complying with specifications, replace both pin and piston.

• Pin - piston clearance: C = b - a
• 0.010 - 0.045 mm (0.0004 - 0.0018 in)
• Limit: 0.060 mm (0.0024 in)

Cylinder - piston coupling

Specification	Desc./Quantity
Piston - cylinder coupling Type A	Cylinder: 91.990 - 91.977 mm (3.6216 - 3.6219 in) Piston: 91.933 - 91.940 mm (3.6217 - 3.6197 in)
Piston - cylinder coupling Type B	Cylinder: 91.997 - 92.004 mm (3.6219 - 3.6222 in) Piston: 91.940 - 91.947 mm (3.6197 - 3.6199 in)
Piston - cylinder coupling Type C	Cylinder: 92.004 - 92.011 mm (3.6222 - 3.6225 in) Piston: 91.947 - 91.954 mm (3.6199 - 3.6202 in)
Piston - cylinder coupling Type D	Cylinder: 92.011 - 92.018 mm (3.6225 - 3.6227 in) Piston: 91.954 - 91.961 mm (3.6202 - 3.6205 in)
Fitting clearance	0.050 - 0.064 mm (0.00197 - 0.00252 in)

See this article in russian language

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Article about repair motorcycles «Aprilia Shiver SL 750» (2007-2016): «Checking the piston»: https://motoinstruction.ru/en/Aprilia/Shiver/SL750/engine/repair/114610 <a href="https://motoinstruction.ru/en/Aprilia/Shiver/SL750/engine/repair/114610">Checking the piston</a> - article about repair motorcycles «Aprilia Shiver SL 750» (2007-2016) from section «Engine repair». [url=https://motoinstruction.ru/en/Aprilia/Shiver/SL750/engine/repair/114610]Checking the piston[/url] - article about repair motorcycles «Aprilia Shiver SL 750» (2007-2016) from section «Engine repair».