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Strange extra ports on head!

Discussion in 'XJ Technical Chat' started by ol_750, Jan 21, 2012.

  1. ol_750

    ol_750 Member

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    I just picked up my 2nd XJ750RL , 45T-000238 motor its a mess

    What I did notice is on the back of the head where there is usually blanked off ports ( level with the intake manifold & directly above the YICS blanking bolts)
    Someone has drilled & inserted phillips head screws & washers in both of these ports.
    8O Any suggestions as to why this would be done ???
    Any benifits?? :roll:
     
    ol_750, Jan 21, 2012
    #1
  2. FJ111200

    FJ111200 Active Member

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    Maybe they didn't have the YICS tool, and are just there to blank off the YICS ports for carb syncronisation. :?: :?: Just a guess.
     
    FJ111200, Jan 21, 2012
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  3. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    I don't think it was "somebody." I think you're seeing a factory production/machining change, and here's why:

    I've got two 550s, one a 1981, the other an '83. Same model-number prefix, 4U8.

    On the 550, there is only one of those "blanked off" ports, on the RH side of the head; however--

    On the early bike, the "port" is simply a blind, unmachined "dead-end" on the casting.

    On the later bike, there is a hex-head phillips screw and sealing washer screwed into the same "port" that's blanked off on the earlier head.

    I can GUARANTEE you that the PO of my later bike didn't do that; the guy couldn't hit his arse with both hands on a good day.

    I think you're seeing a similar situation. I believe that something changed in how they were machining the heads; or for some reason they felt the need to open up a passageway that had previously been left blanked off. WHY is beyond my pay grade.

    Check your serial parts of the serial numbers, is it the earlier or later motor with the screws?
     
    bigfitz52, Jan 21, 2012
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