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.

Xj750 Keeps dying out

Discussion in 'XJ Technical Chat' started by Alex miller, Jun 25, 2026 at 11:49 PM.

  1. Alex miller

    Alex miller New Member

    Messages:
    9
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Hershey PA
    Hello, my 1982 xj750 seca keeps dying, this bike is a project and hasn’t been ridden more than up the street since I bought it not running. I rebuilt the carbs for the 3rd time and it started up and sounded great ran great, however it did backfire plenty upon acceleration. Eventually it died out as it had upon the few other previous attempts at riding it(it didn’t run as nice this times however or make it as far(0.5 the first few attempts almost a mile on the most recent.) When the bike dies out it will still crank but won’t start. This most recent run I took it home after it died and and it started right up with starting fluid but wouldn’t run great, when I had the choke open it would rev up and then slowly rev down, it also backfired plenty it also won’t rev sometimes while I was playing with the choke. I’ll try to attach the video I have of me playing with it.

    video link(Google drive): https://drive.google.com/drive/folders/19CENOojTCqYuBTX5zWdiUxM2jLZa8GZG
     
  2. cds1984

    cds1984 Well-Known Member

    Messages:
    1,217
    Likes Received:
    300
    Trophy Points:
    83
    Location:
    Perth, Western Australia
    2 things.
    Take a spark plug socket and ratchet with you when you test ride it.
    When it dies or starts going to shite, pull over and pull the plugs and see if they are dry or wet or super black and wet.
    I had a rich idle circuit and too large main jets way back.
    Ran great then flopped about at high speeds then died.
    I was carrying a few tools to unfoul the plugs and get going again.
    Could be your issue... Or lack of fuel, crimped hose, bad filter, clogged air filter it's goes on and on!
     
  3. Alex miller

    Alex miller New Member

    Messages:
    9
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Hershey PA
    Yeah, so went it was first dying out I checked the spark plugs and they were black one wasn’t wet but I believe it was just fuel as it evaporated, I adjusted the jets from where the previous owner had them(main fuel 136-120, pilot fuel from 112-40) and I checked the spark plugs and they all looked good this time so maybe now it’s running lean? It does have pod filters and rn the jetting is completely stock. I used an aftermarket fueling/filter because of the condition of the tank, but I unscrewed the one bowls drain and it had fuel in it the others were all stripped long before me.
     
  4. Alex miller

    Alex miller New Member

    Messages:
    9
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Hershey PA
    One thing I noticed plenty of is back firing and a weird rev hang with the choke engaged. There’s a video in the original post, if that helps.
     
  5. cds1984

    cds1984 Well-Known Member

    Messages:
    1,217
    Likes Received:
    300
    Trophy Points:
    83
    Location:
    Perth, Western Australia
    Choke engaged is a weird thing on these carbs.
    It really means flooding the cylinder with fuel from the bowl. Not choking air. Fuel enrichment circuit is the term.
    If you look at it that way, sans pods issues, it may help also.
    Backfiring means unburnt fuel heading out the exhaust valve or just remaining on the input valve cycle depending on your backfire experience.
    So super rich or a timing issue or a valve issue.
    I will recite the cv carbs mantra.
    Carb sync, carb float levels, carb main and pilot jets, idle mix screw and... Valves and... Compression.
    All magical stuff.
    Start at valves then carbs. Be strong! It'll work out.
     
  6. cds1984

    cds1984 Well-Known Member

    Messages:
    1,217
    Likes Received:
    300
    Trophy Points:
    83
    Location:
    Perth, Western Australia
    You may have seen the YouTube video for cleaning plugs that are rich. It's basically cooking the hell out of the plug with a torch, hard to do on the road but essentially what a clean running system does.
    Map gas torch and a bit of patience before you melt the plug and it burns away the carbon on the insulator which is the main issue when super rich.
    A new set of plugs is easier but doesn't help when trying to dial it in.
     

Share This Page