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Carb issues

Discussion in 'The Garage' started by Dan43, May 23, 2020.

  1. Dan43

    Dan43 XS400 Member

    Hi I have an 81 xs400 special I got about 3 years ago as my first bike I love it and this site has been amazing for all kinds of help and tips. Thank you so much all of you. I moved from Austin, Texas to Cincinnati, Ohio about a year ago I’ve had all kinds of trouble since I got here including my bike being towed and since I didn’t have a title or registration my only choice was to buy it back in auction but I did so for less than it would’ve cost to get a title so it worked out. Upon getting it back the bike was not running right at all I found out I had some electrical problems after solving that and upgrading my electronics and doing some cosmetic stuff I’m having a hard time getting the carbs dialed. I’ve read a lot on here about jets needles and everything. When I first got the bike I took my carbs to a local shop to get cleaned as I was completely new and wanted to get it done right and not be second guessing my work well it ran perfectly I told the guy I ran pod filters and open exhaust so he said he would jet it appropriately but now I’m not sure if it’s the elevation or what but the bike bogs down pretty hard somewhat randomly mostly when taking off at light or whatever sometimes and sometimes not at all I’ve tried all kinds of things riding wise as I thought this was a me problem and it seems to ride better the easier I go on the throttle. Someone had mentioned I need to adjust float height maybe there was enough gas in the float bowl. So I pulled the carbs cleaned them and checked float height it was set at 30mm I read on here it should be 26mm so I made the adjustment and set my mixture screws for 3 turns out. Got it all back together and try to start it and after a few kicks it started but not running good I figured the air mixture needed adjustment but seeing as how they are hard to get to and I don’t have a shop it’s kinda hard to adjust mixture on the bike while it’s running. So I turned them out to 6 turns which I feel is insane compared to what most people post on here anyway it rode much better but still bogs down a bit on take off I do plan on putting on some type of slip on muffler eventually just haven’t figured out what I want. Current carb jetting is as follows:
    145 main
    45 pilot
    Needles are the kind without notches
    6.5 turns out on air mixture
    Floats set at 26mm
    Open exhaust
    Cheap pod filters
    I know pods and open pipes aren’t ideal but I didn’t have this problem at all before moving. Anyway if you’ve made it this far thanks and I appreciate any advice sorry if I’m annoying.
     

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  2. Dan43

    Dan43 XS400 Member

    From what I’ve read I think I’m bogging down due to running too rich so having my screws out twice as far as what most say on here kinda makes me feel that’s the problem but if richening the mixture by going from 3 turns out to 6 turns out helped then I’m lost but if it’s normal for my screws to be out so far should I just keep going or mess with the jets? I feel like I’m soooooo close i have no back firing no popping just kinda bogs down every once and a while
     
  3. xschris

    xschris a lifestyle not a trend Top Contributor

    I would put the stock intake H-pipe back on and get some black foam uni filters the ones you have are not going to tune well for these type carbs. Yes, a muffler of some sort would be better than nothing. Floats should be around 26mm for brass floats and 22mm for the foam ones. That is without the bowl gasket in place. 4 turns out is max for the pilot mix screws. Post some pics of the plugs. Have you synced the carbs with a manometer yet?
     
  4. Dan43

    Dan43 XS400 Member

    Yeah I’ve read that on here a lot but it’s just strange that it ran perfect before. I have brass floats and these carbs are the ones that aren’t in the Haynes manual. I haven’t synced them I guess I’ll try that. 4 turns out max? So then i need a different jet right?
     
  5. xschris

    xschris a lifestyle not a trend Top Contributor

    Pull the plugs and post pics. They can tell you a lot about your jetting.
     
  6. Dan43

    Dan43 XS400 Member

    Awesome thanks I’ll check em tomorrow and post a pic
     
  7. xschris

    xschris a lifestyle not a trend Top Contributor

    Extremely rich on all stages it looks!!! I would get new plugs and lean the bike out.
     
  8. Dan43

    Dan43 XS400 Member

    Thanks a lot I appreciate your help
     

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