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Main bearing journal number location?

Discussion in 'The Garage' started by DannyfromNZ, Feb 8, 2020.

  1. DannyfromNZ

    DannyfromNZ XS400 New Member


    I`m currently rebuilding my yamaha xs400-12e 1983 engine. The main problem is now that I can`t find the journal number on the engine block. The service manual seems to be showing that it`s located on the top block half behind the alternator on the left hand side. All I can find there is a couple of numbers and a few letters which are hand written and it doesn`t add up. Could someone take a photo of their number so I can see where it`s supposed to be?

    The other question is if somebody knows of somewhere you can buy new standard size pistons as mine are damaged

  2. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    You might be out of luck dude. Bearings are super expensive if they are available anywhere. I remember seeing shell bearings selling for quite a lot ($60 USD) for just one half of the bearing..

    Standard size pistons might be obtainable, since everyone usually just moves up the next size. Whats wrong with the pistons? If you can get away with a hone, you can find new piston rings.

    The procedure for getting the bearing sizes is tricky. Theres numbers on the case that you need to add or subtract or something to get the right size. The bearings had revisions through the years also with added holes for oiling and such. The connecting rod bolts are one-time use and those are probably non existent by now. Do not remove the con rods if you can spare them.
  3. DannyfromNZ

    DannyfromNZ XS400 New Member

    I do see people who sell NOS bearings om Ebay every now and then , but yes , they are hard to get hold of these days. But in my case I can't find my journal Numbers on the the engine block to determine which bearing to use.

    The problem with the pistons is that they both are lightly scored and one of them has got a big mark in it , from I don't know what.

    But as I can't seem to find standard sized pistons easily I'm thinking of drilling my cylinder Up to the next oversize which seems to be +0,25mm , well I know it Costa money but it seems simpler.

    And the bearing calculation process isn't all that complicated once you've worked it out , you need to subtract the Numbers on the block from the ones om the conrods or the other way round. And the result tells you which bearing to use. Like blue has got a certain number and brown another etc

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