TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: udontknowme on August 07, 2013, 01:57:17 AM
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if everything was new how much you figure the rod would stretch. .005" at the very most ? and where would the stretch take place. mostly at the top so the piston would get closer to the head ? trying to trench some cases and i think .015- .020" clearance between rod and cases should be plenty because i dont see the bottom of the rod growing any closer to the case. what you guys think ?
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The rod would not be stretching at the crank pin, so clearance is not a big issue around the case bottoms, the case tops clearance can change alittle with wear in the bearings and piston/bore but .015-.020 will fine for all that.
The room needed for the squish clearance between the piston top and cylinder head growth is because of some rod stretch but also bearing clearances and piston rock in the cylinder so the amount of stretch really is very little.
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Bolt the cylinder on 1 case half with the crank and piston installed to check for proper rod clearance at the top of the cases while rotating the crank and mark the areas that are tight.
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ya i found the tight spots. at the bottom is .014" and top it rubs. will get it evened out tomorow