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Question on Main Jet sizing

Discussion in 'The Garage' started by BambinoFan, Jul 8, 2022.

  1. BambinoFan

    BambinoFan XS400 Member

    Hey friends,
    Looking to rebuild my carbs to deal with a running idle issue - Thinking the diaphragms are shot. While I'm in there figured I might as well re-jet the whole thing. Ordered a rebuild kit from Taiwan, now I'm just confused about the main jet sizing. Baby is a 84 xs400j Maxim.

    The manual says that I need two sizes, 127.5 and 120, for left and right, respectively. The kit I ordered comes with 112, 125 and 142.5. Could I use the 125 and the 112 for the left and right, and just turn them out/in more than they are now? Or did I slip and should I order another set of jets altogether?
  2. CaptChrome

    CaptChrome XS400 Addict

    Main jet replacement won't help an idle issue. I would rebuild the carbs with the stock jets first, tune the bike with those, ride it for a bit and then decide on re-jetting. Making too many changes all at the same time can lead you down a frustrating rabbit hole of problems.
    BambinoFan and tstidham like this.

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