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Main bearings


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Yes i bought the shee off a fella who just stashed it in his shed when he bought a yfz450. Said it was low on compression when he put it away. When i got the jugs off, one of the rings was a lil wonky on the right side and the cylinder wall had very light scoring to match. Decide to just do fresh seals all around, new mains, fresh bore/top end. Damn i shoulda left it alone lol

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the main thing is you want the rods running straight up the bore. use the stud holes as reference ( assuming theyre sqaure to the bore and not offset for some dumb reason but most engines use studs sqaure on the bore) and put a pencil mark on each case at center and align the rods on the mark. if the crank hasent seperated or some dumb hillbilly hasnet taken it apart, then you should be good and that should center up your crank wheels also, because from the pics theyre shifted a mile to the flywheel side.

 

dont worry about the flywheel side bearing. since it doesnt have a dowel or clip, its mostly irrelevant if its on the shaft all the way or not

 

roller bearing inner race shouldnt be putting a bunch of side pressure on the rollers. on the other hand it needs to be inside the bearing far enough that the rollers are making full contact. make sense

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Just busted out the calipers and measured from stud to stud and the center of conrod lines up with what appears to be perfect center of the two studs, but the crankshaft still looks off center to the stator side.... My clutch side bearing is all the way on so it isnt even possible to move the shaft any more in that direction. Conrods line up to center of studs and crankshaft spins smooth and true. Only thing is its close to the case on the stator side. Am i safe to assume thats the fit of this crank/ case? Wish i took a picture of it before yanking the stock mains and replacing them!

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you guys are a big help! Thanks alot. Now.... Best way to get the sealant off the sealing surfaces so i can get some new stuff on there and seal her up? Used thinner and a scotch brite pad the first time but that was a pain in the ass!

 "Some" brake cleaners seem to work ok, laquer thinner or Cassey-Birchwood Gun scrubber melts that shit good. Use a plumbers acid brush to spread sealer evenly, try not to get it in threaded holes. Make sure they are cleaned out too.

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