1. Some members were not receiving emails sent from XJbikes.com. For example: "Forgot your password?" function to reset your password would not send email to some members. I believe this has been resolved now. Please use "Contact Us" form (see page footer link) if you still have email issues. SnoSheriff

    Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

Xj650 turbo carbs

Discussion in 'XJ Technical Chat' started by murray9982, Apr 7, 2016.

  1. murray9982

    murray9982 New Member

    Messages:
    26
    Likes Received:
    5
    Trophy Points:
    3
    Location:
    Australia
    Hi, it,s been a while ,but back again with new project. I started cleaning and refurbishing xj650 Turbo Mikuni carbs and have noticed that carbs 1 & 2 have 127.5 main jets ,while 2 & 3 have 137.5 main jets . From my searches ,this seems to be correct , although not listed this way by Yamaha . I would like to confirm that this is correct, and appreciate any info on why it was done this way , cheers , Murray
     
    murray9982, Apr 7, 2016
    #1
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

    Messages:
    19,647
    Likes Received:
    6,755
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    On the Turbo 2 and 3 need to run richer in order to keep the combustion chamber and valves cool.
     
    k-moe, Apr 7, 2016
    #2
  3. murray9982

    murray9982 New Member

    Messages:
    26
    Likes Received:
    5
    Trophy Points:
    3
    Location:
    Australia
    Thanks for the reply. I thought it most likely something like that ,will put back together when
    parts arrive from Len
     
    murray9982, Apr 8, 2016
    #3
  4. murray9982

    murray9982 New Member

    Messages:
    26
    Likes Received:
    5
    Trophy Points:
    3
    Location:
    Australia
    Actually , that was 132.5 2 & 3 , mistype , no matter
     
    murray9982, Apr 8, 2016
    #4
  5. a100man

    a100man Well-Known Member

    Messages:
    1,627
    Likes Received:
    358
    Trophy Points:
    83
    Location:
    Bedford, UK
    K, not just the Turbo I think. This comes up quite often and most are like that..
     
    a100man, Apr 8, 2016
    #5
  6. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

    Messages:
    19,647
    Likes Received:
    6,755
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    I am aware that it's not just the turbo that has richer jets on 2&3.
     
    k-moe, Apr 8, 2016
    #6
  7. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    13,199
    Likes Received:
    3,861
    Trophy Points:
    113
    Location:
    Great North Woods
    from
    http://xjbikes.wikidot.com/carb-specs

    Years & Models: 1984 XJ550L Maxim models
    Carb Manufacturer: Mikuni
    Carb Series: BS32
    Carb Model ID: 5K500
    Main FUEL Jet Size: #105 (cylinders #1 & 2)
    Main FUEL Jet Size: #102.5 (cylinders #3 & 4)
    Pilot FUEL Jet Size: #40
    Main AIR Jet Size: #70 (non-removable, in carb throat)
    Pilot AIR Jet Size: #155
    AIR COMPENSATOR Jet Size: not used.
    Starter FUEL Jet Size: #42.5 (non-replaceable, in float bowl)
    Main jet NEEDLE ID: #4CP7-3 (cylinder #2)
    Main jet NEEDLE ID: #4CP3-3 (cylinders #1, 3, and 4)
    Main needle JET Size: #N-8 (the main needle JET is also known as the "power valve" or "emulsion tube").
    Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
    Idle RPM's: 1,200 rpms

    Years & Models: 1983 XJ750E-II models
    Carb Manufacturer: Hitachi
    Carb Series: HSC33
    Carb Model ID: 29R00
    Main FUEL Jet Size: #105 (cylinders #1 & #4)
    Main FUEL Jet Size: #102 (cylinders #2 & #3)
    Pilot FUEL Jet Size: #40
    Main AIR Jet Size: #70
    Pilot AIR Jet Size: #225
    AIR COMPENSATOR Jet Size: not used.
    Starter FUEL Jet Size: #43 (non-replaceable, in float bowl)
    Main jet NEEDLE ID: #Y-17
    Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
    Fuel Level in float bowls: 5mm +/- 1mm (.197" +/- .039")
    Idle RPM's: 1,050 rpms

    and of course the turbo
    Years & Models: 1982-3 XJ650LJ/LK Turbo Seca North American models
    Carb Manufacturer: Mikuni
    Carb Series: BS30
    Carb Model ID: 16G00
    Main FUEL Jet Size: #127.5 (cylinders #1 & #4)
    Main FUEL Jet Size: #132.5 (cylinders #2 & #3)
    NOTE: the yamaha parts books reference the use of #125 main fuel jets. Original carbs that we have explored have the #127.5/#132.5 combination of jets as shown above.
    Pilot FUEL Jet Size: #35
    Main AIR Jet Size: #70 (non-removable, in carb throat)
    Pilot AIR Jet Size: #170
    NOTE: the yamaha parts books reference the use of #165 pilot air jets for the 1982 models, and #155 pilot air jets for the 1983 models. Original carbs that we have explored have the #170 jets as shown above.
    AIR COMPENSATOR Jet Size: not used.
    Starter FUEL Jet Size: #30 (non-replaceable, in float bowl)
    Main jet NEEDLE ID: #4DPS39
    Main needle JET Size: #O-6, #318 style (the main needle JET is also known as the "power valve" or "emulsion tube").
    Fuel Level in float bowls: 2mm +/- 1mm (.08 +/- .04 inches)
    Idle RPM's: 1,050 rpms
     
    XJ550H, Apr 8, 2016
    #7
  8. a100man

    a100man Well-Known Member

    Messages:
    1,627
    Likes Received:
    358
    Trophy Points:
    83
    Location:
    Bedford, UK
    Of course..
     
    a100man, Apr 8, 2016
    #8

Share This Page