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Post by gazw on Jan 9, 2019 20:38:26 GMT
Well Ive got the engine out and the head back off and nothing is to amiss (well no major unrepariable damage anyway) Ive taken the engine , head an barrels to a engine builder and he says that the rings on top odf the piston are casting marks We both wasnt sure what the gouge in the piston is from ,(the gouge does look a lot worse on the pics than in real life) barrel opposite the gouged piston does have some scoring , so im having it rebored anyway and two new 0.25 oversize pistons from silvers Some better pics of the latest findings
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Post by buster on Jan 10, 2019 10:38:59 GMT
it almost looks to me as if a piece of debris has gone in through the intake, done the damage and then been spat out again? if it was mine I'd be having a good look in the airbox ensuring that everything is clean and no bits and pieces lurking in there. also if it was debris pulled in through a port I'd strip and decoke the head and lap the valves back to their respective seats but thats just me.
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Post by gazw on Jan 10, 2019 14:14:58 GMT
I did have the head pressure tested yesterday and all was fine there , there was a tiny bit of leakage from one of the inlets , but this was put down to a defective o ring on the rubber
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Post by alfie on Jan 10, 2019 19:29:07 GMT
Save your money, re-ring and hone the bores
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Post by buster on Jan 11, 2019 9:53:47 GMT
honing the bores is ok for a piston ring change but if one of thems scored (as gaz says above) its not going to work. personally I use hobbsport racing for rebores as they're a good firm that take the care required to bore to the correct size and then hone to within a tenth (thats a tenth of a thou), the better the seal betwwen bore and piston the better the engine
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