Step 1: Clean pistons: First clean the pistons thoroughly and remove all carbon deposits from the ring grooves. Use a twist drill and tap wrench to remove the carbon deposit from the oil drain holes. Replace cracked or deformed and worn pistons.
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Step 2: Check piston ring grooves: If a clearance of 0.12 mm or more is measured between a new, parallelsided compression ring and the associated groove wall, this means that the piston is excessively worn and has to be replaced.
| ![]() Measure the piston ring grooves using a gauge, KS Art. No. 50 009 824 | ||||||||||||||||||||||||||||||
Step 3: Check the cylinder wear: If the cylinder wear exceeds 0.1 mm for SI engines and 0.15 mm for diesel engines, the cylinder also has to be exchanged (top ring reversal bore wear).
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Step 4: Clean the cylinders: Remove carbon deposits from the top area of the cylinder bore, above the ring travel zone. | ![]()
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Step 5: Check the ring set components: When fitting the pistons with new rings, we recommend in principle to exchange the complete set. Check the ring height by means of a measuring gauge. It is recommended to compare with our Catalogue data. | ![]() ![]() Checking with dial-type KS measuring gauge, accuracy 0.01 m, KS Art. No. 50 009 824
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Insert piston rings in the associated piston ring groove using the right assembly tool! Avoid excessive opening of the piston rings on fitting as this would cause permanent deformation and impair the performance of the piston rings. | ![]() Piston ring pliers KS-Artikel-Nr. 50009815 for ø 50 - 100 mm KS-Artikel-Nr. 50009829 for ø 60 - 160 mm
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When fitting rings with spiral expander the spring ends should always be positioned opposite the ring gap. Some spiral expanders pass through a teflon tube, which is located opposite the spring ends and therefore directly beneath the ring gap.
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Step 6: Function test / Turning the piston rings: After fitting the piston rings, make sure that they can be freely moved. Position the ring gaps with 120° off-set to the next ring.
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Step 7: Fitting the piston into the cylinder bore: Oil the piston rings and the piston appropriately and use a ring compressor or a conical KS assembly sleeve in order to prevent damage to the piston rings.
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Ring compressors / Assembly sleeves
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