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What should I be looking for? (engine/carb)

Discussion in 'XJ Technical Chat' started by 82XJ, Apr 23, 2007.

  1. 82XJ

    82XJ Member

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    I haven't brought my Max (82 XJ750J) home yet, so I haven't been able to tear into it. But I was able to take a look at it over the weekend, so maybe you guys can help me figure out what I'm looking at...

    Here's the rundown:
    -Starts up pretty easily, but needs some throttle to start.
    -Idles/runs rough until well warmed up.
    -Idles high.
    -Pops and sputters constantly, even when warm.
    -Even when warm, can't take it all the way off choke.

    Now, my best guess is that all of those sound like classic symptoms of carburation problems, and that a good clean/tune/sync should clear them up. However, I'm no expert, and totally new to XJ's, so maybe you could tell me if there's anything else I should be checking/worried about. :)

    Thanks!
     
  2. ToddMackenzie

    ToddMackenzie Member

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    The engine will always rev high when the choke is on. If you can't take the choke off, then maybe the idle adjustment screw needs to be tightened. Also, synchronizing the carburetors is also a good way to get your bike running better. These two adjustments can be done without pulling the carburetors, so it's a good place to start. You can also make your own synchronizing tool with some hose, some T-connectors and some oil for only a few dollars.
     
  3. 82XJ

    82XJ Member

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    Thanks Todd...

    I probably should have been more clear: I fully plan on a complete carb teardown, cleaning, colortune and sync. I've read most of the relevant threads here and have a shop manual on the way.

    More specifically, though, I was just wondering if there was anything else I should be watching for. Apparently the bike sat outside for some time, though the person I'm buying it from seems to have done a pretty good job cleaning it up.

    It needs to have the brakes adjusted at least, and new tires for sure. It shifts into all the gears OK, and does ride down the road OK (or would, if it ran better).

    Am I missing anything?
     
  4. Russxlr8s

    Russxlr8s Member

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    It sounds like your on the right track. If the bike has sat for 5 to 6 months straight with no running, you are going to have gas that has turned bad and like varnish, even worse in more time. Passages can get blocked as the gas can dry over them like a thin skin, a complete cleaning of the carbs & bowls and all holes is almost always needed.

    As well as when the float needle's sit stuck in their needle seat, they can get sticky and the rubber tips hardened by the varnished over gas, and when your float needles fail, it can drain your tank into the engine through an intake valve and when started blow a gas oil mix into the air filter box and come out all over the place.

    All these old bikes don't take well to sitting long durations without running, that's why I always recommend every few weeks for folks to start and run their bikes throughout winter storages etc.

    Good luck, keep at it.
     
  5. RickCoMatic

    RickCoMatic Well-Known Member

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    Get the Carbs off and Clean and Super-Tune 'em!

    Set-'em-up for Mach-1 and get babies back-on-there in time for weekend Tweak, Tune and Track-test.
     

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