Suzuki outboard motors 1988 2003 repair manual., Page 249Get this manual
POWERHEAD 7-37 the piston rings to seal against and transfer heat to the cooling systemThese functions are carried out through all engine speedsTo function properly the cylinder has to have true machined surface and must have the proper finish installed on it to retain lubricantREFINISHING
If the cylinder is out of round, worn beyond specification, scored or deeply scratched, reboring will be necessaryIf the cylinder is within specification, it can be deglazed with flex hone and new rings installed,
Some cylinders are chrome plated and require special service proceduresConsult qualified machine shop when dealing with chrome plated cylindersINSPECTION
See Figures 31 and 32
The roundness of the cylinder diameter and the straightness of the cylinder wall should be inspected carefullyMicrometer readings should be taken at several points to determine the cylinder conditionStart at the bottom using an outside micrometer or dial bore gaugeBy starting at the bottom, below the area of ring travel, cylinder bore diameter can be determined and determination can be made if the powerhead is standard or has been bored oversizeTake the second measurement straight up from the first in the area of the ports and note that the cylinder is larger hereThis is the area where the rings ride and it has worn slightlyTake the third measurement within half inch of the top of the cylinder, straight up from where the second measurement was takenThese three measurements should be repeated with the measuring instrument turned 90' clockwiseAfter the readings are taken, you will have enough information to access the cylinder conditionThis will tell you if the rings can simply be replaced or if the cylinder will need to be overboredWhile measuring the cylinder, you should also be noting if there is cross-hatched pattern on the cylinder wallsAlso note any scuffing or deep scratchesFig31 The roundness of the cylinder diameter and the straightness of the cylinder wall should be inspected using dial bore gauge
Almost all engine block refinishing must be performed by machine shopIf the cylinders are not to be rebored, then the cylinder glaze can be removed with ball honeWhen removing cylinder glaze with ball hone, use light or penetrating type oil to lubricate the honeDo not allow the hone to run dry as this may cause excessive scoring of the cylinder bores and wear on the honeIf new pistons are required, they will need to be installed to the connecting rodsThis should be performed by machine shop as the pistons must be installed in the correct relationship to the rod or engine damage can occurWhen deglazing, it is important to retain the factory surface of the cylinder wallThe cross-hatched patter on the cylinder wall is used to retain oil and seal the ringsAs the piston rings move up and down the wall, glaze developsThe hone is used to remove this glaze and reestablish the basket weave patternThe pattern and the finish is has satin look and makes an excellent surface for good retention of 2-stroke oil on the cylinder wallThere is nothing magic about the crosshatch angle but there should be one similar to what the factory used(approximately 20-40')Too steep an angle or too flat pattern is not acceptable and as it is not good for ring seatingSince the hone reverses as it is being pushed down and pulled up the cylinder wall, many different angles are createdMultiple criss-crossing angles are the secret for longevity of the cylinder and the ringsThe pattern allows 2-stroke oil to flow under the piston ring bearing surface and prevents metal-to-metal contact between the cylinder wall and piston ringThe satin finish is necessary to prevent early break-in scuffing and to seat the ring correctlyAfter the cylinder hone operation has been completed, one very important job remainsThe grit that was developed in the machining process must be thoroughly cleaned upGrit left in the powerhead will find its way into the bearings and piston rings and become embedded into the piston skirts, effectively grinding away at these precision partsRelate this to emery paper applied to piece of steel or steel against grinding stoneThe effect is removal of material from the steelGrit left in the powerhead will damage internal components in very short timeWiping down the cylinder bores with an oil or solvent soaked rag does not remove gritCleaning must be thorough so that all abrasive grit material has been removed from the cylindersIt is important to use scrub brush and plenty of soapy waterRemember that aluminum is not safe with all cleaning compounds, so use mild dish washing detergent that is designed to remove greaseAfter the cylinder is thought to be clean, use white paper towel to test the cylinderRub the paper towel up and down on the cylinder and look for the presence of gray color on the towelThe gray color is gritRe-scrub the cylinder until it is perfectly clean and passes the paper towel testWhen the cylinder passes the test, immediately coat it with 2-stroke oil to prevent rust from forming Rust forms very quickly on clean, oil free metalImmediately coat all clean metal with 2-stroke oil to prevent the formation of rustGENERAL INFORMATION