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XJ 650 4K0 M.Y. 1980 main bearings - help with color codes and correct spare parts numbers

Discussion in 'XJ Technical Chat' started by Charlie_TDM, Oct 26, 2017.

  1. Charlie_TDM

    Charlie_TDM New Member

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    Hello fellow XJ 650 owners,

    I would like kindly ask you for help: I am working on the engine of XJ 650 4K0 M.Y. 1980 (European model) and I am little bit confused about shells colour codes and ordering numbers of spare parts.
    On my crankshaft are these numbers: 1 3 2 2 2 / 1 1 1 2
    On the crank case are these numbers: 5 5 5 4 5 (I know, it´s from the right to the left, so for the calculation I use opposite order)
    On each con rod is E5

    So my opinion is for main bearings I need 4 1 3 3 3 - green, blue, brown, brown, brown.
    For con rods I need 4 4 4 3 - green, green, green, brown

    Does anybody know correct ordering numbers? In the Yamaha spare part shop are different ordering numbers without color codes. Can somebody help me with this topic, please?

    I will really appreciate any help. Thank you in advance, Charlie
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    from xj4ever catalog

    ENGINE BEARINGS:

    Crankshaft Bearings:

    Yamaha used a unique way of "sizing" their engine bearings, both for the crankshaft main journal bearings and the connecting rod big-end bearings.

    The factory coded, via a series of numbers indicating a "size code", numbers onto the crankcase, the crankshaft, and the connecting rods.

    The crankCASE has numbers hand-scrawled onto the upper (and possibly the lower, also) engine case(s) ---typically, behind/below the stamped pad where the engine ID number is, behind the clutch cover opening, but, in reality, could be anywhere on the case(s) --- that specifies the main bearing saddle sizes for that particular engine case:

    http://www.xjbikes.com/forums/threads/complete-xj650-rebuild.81981/page-2#post-498539

    Note that these last 2 sets of 2 numbers --- “40’ / 46” and “45 / 40” in the above examples --- are the codes used for calculating the thickness of the shims used with the middle gear drive shaft of each particular engine.


    The crankSHAFT will have two grouped sets of numbers on one end. The first set of 5 numbers are the main bearing journal size numbers for that crankshaft, and the second set of 4 numbers which denote the rod bearing journal numbers for that particular crankshaft. Both sets of numbers refer to the crank journals starting at the left side of the crankshaft (the #1 cylinder side, see the last picture in the post below):

    http://www.xjbikes.com/forums/threads/complete-xj650-rebuild.81981/#post-498538


    Each connecting rod also has a number that is stamped (with ink) on the rod itself, right where the upper and lower shells meet.


    To calculate the correct bearing sizes to use in a particular engine, you will go through the following process:

    Crankshaft Main Bearings:

    The correct main bearing selection is made by subtracting the crankshaft journal number from the engine case main bearing saddle size number, for each main bearing journal position.


    Connecting Rod Big-End Bearings:

    The correct bearing selection is made by subtracting the crankshaft journal size number from the rod size number, for each rod/crank journal position.


    For both the crank main journal bearings and the rod bearings, you will then use the numbers calculated above to realize a "bearing color" as outlined in the chart below. You would then order the correct "color" bearing for each crankshaft main journal or connecting rod big-end position:

    Bearing "Color Codes":

    #1 = Blue
    #2 = Black
    #3 = Brown
    #4 = Green
    #5 = Yellow

    A good visual of the color marking on the bearing can be seen at:

    http://www.xjbikes.com/forums/threads/complete-xj650-rebuild.81981/page-2#post-498544



    Example:

    - Crankshaft is marked 21223 2111
    - Engine case is marked 34534 48 47 (note that these last 2 sets of 2 numbers --- ’47’ and ‘48’ in this example --- are codes used for calculating the thickness of the shims used with the middle gear drive shaft)
    - Rods are marked 6, 4, 3, and 3

    The first set of 5 numbers on the crankshaft (21223) are the main bearing journal sizes for that crankshaft, and are sequentially #1 to #5 as read. The corresponding 5 numbers scratched onto the engine case (34534) are the main journal saddle sizes for that engine and are sequentially #5 to #1 as read. For the #1 main journal position (the far left position), we would have 4 (on the engine case) - 2 (on the crankshaft) = 2. The #1 main journal bearing is a "size" 2, which is a "black" bearing.

    NOTE THAT THE HAND-SCRAWLED NUMBERS ON THE CRANKCASE READS JOURNALS #5 TO #1 as you read them left-to-right, and thus in a 5/4/3/2/1 sequence for the main journal bearing sizes! They are actually "backwards" from an intuitive approach (and "backwards" from the sequence they are coded onto the crank itself), but are "correct" in spatial orientation and sequence for the top crankcase half (since they are scrawled "reverse" in relation to the crankshaft position within the crankcase).


    For the #1 con-rod, using the example above, you would use the 2nd set of numbers on the crankshaft (2111), and the ink-stamped number on the rod itself. So the #1 rod is stamped as 6, and the #1 crank rod journal is 2, and 6 - 2 = 4. Thus the #1 rod was use a "size" 4 connecting rod bearing, which is a "green" bearing.


    Notice that it is NOT unusual for a single crankshaft to use a variety of different "size" or "color" bearings.


    NOTE: The yellow "size" bearings are used only for crankshaft main journal bearings. Rod bearings were never made nor available in the yellow "size".

    IN ALL CASES YOU SHOULD REFER TO A FACTORY SERVICE MANUAL OR A SKILLED, EXPERIENCED MACHINIST AS TO HOW AND WHAT SIZE ENGINE BEARINGS THAT NEED TO BE PURCHASED AND USED DURING AN ENGINE REBUILD! DO NOT PURCHASE ENGINE MAIN OR ROD BEARINGS BASED ON THE "NUMBERS" ALONE----ALWAYS PLAN YOUR ENGINE REBUILD PARTS NEEDED ONLY AFTER ENGINE DIS-ASSEMBLY, PARTS MEASUREMENT, AND CONSULTATION WITH A MACHINIST.


    Crankshaft Main Bearings:
     

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