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81 XJ650H wierdness afoot . . .

Discussion in 'XJ Technical Chat' started by railtramp, Apr 28, 2008.

  1. railtramp

    railtramp New Member

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    Hey all-

    I have an 81 XJ650H Maxim that has run great for years. It had a leaking petcock that would only work when set to the 'prime' position so I decided to rebuild it, which I did yesterday. At the same time, I decided to change the spark plugs as well as the filthy air filter, and everything went dandy until I tried to start it. Now it hardly runs. Without the choke, it barely idles. I've adjusted the idle speed via the cable up near the throttle, but it is either 4k RPM or stuttering around 500. And when I apply a little choke, it jumps up to 5k RPM. If I keep the idle high and try to ride it, it immediately begins to bog down and it dies. And if that all weren't weird enough, now when I turn the handlebars to the right, the idle speed again jumps up to almost 4k. I have watched the throttle cable VERY closely while doing this and am 99.2324% sure that it is NOT moving with the handlebars--at least not pulling the cable where it attaches to the carbs. I can watch it move by pushing and pulling on the throttle cable with my hand, but there is NO MOVEMENT when I turn the handlebars right--just and incredible increase in idle speed. Any ideas? I am sure one thing I should do is clean the carbs, as that seems to be a common element among the threads I have read. Any ideas on how much that should cost, as I don't want to mess it up. And do they need to be sync'd after that? And lastly--just because it may matter--one of the mufflers is worn through and needs replaced. Not sure if that would matter, but it is the only other thing on the bike that I can tell needs replaced. Any advice would be so greatly appreciated, as it is the first sunny day in weeks in Montana and I'm stuck at home with an unhappy ride!!!

    Thank you so much!!!!

    Dan
     
  2. leadboots

    leadboots Member

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    make sure the petcock is flowing good
     
  3. simona

    simona Member

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    You are the lucky owner of an XJ650 that can turn clockwise at 90 mph, Ok as long as you keep turning right.
    Seriuosly though it sounds like you need to give the carbs a really good clean, if the pilot jets are blocked you will have poor idle, and if the carbs are slightly out of synch then you will get the 'racing at 4k' problem. There are lots of good posts on carb cleaning, and bench syncing, and correct float level on this site. Its not too hard to do. My guess is that the throttle cable is pulling a bit when you turn the bars and causing the throttle to open a little, it doesnt take much movement
     
  4. Old-Grunt

    Old-Grunt Member

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    you have to have a little play in throttle cable!!!! readjust cable so you have a little monement in throttle grip I shoot for 1/16 or a touch more...
    you adjust idle speed with the little star wheel at back of carb rack between 2nd and 3rd carb,,I'm not a safty freak at all but a tight cable is dangerious,you see what happens you turn bars and it gives it gas...
     
  5. railtramp

    railtramp New Member

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    so far i've rechecked the petcock. seems to be working great. in the prime position, fuel pours out. in the on position, fuel comes out if you suck on the vacuum tube. as for the idle and safety issues, i've only played with the idle speed near the throttle to try and get it to run. i will ABSOLUTELY make sure there is play when i ride it!!! still running about as good as a 15 year old dog with two legs, though. completely stumped . . .
     
  6. Old-Grunt

    Old-Grunt Member

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    sounds good!!! I've done same thing myself,some 2 strokes dont have a dedicated I'dle speed adjustment so thats one way to keep running while tuning
     
  7. xyxj650

    xyxj650 Member

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    I just had the same problems with my bike. I went through my carbs and cleaned them and reset my float levels and done a bench sync. Runs good now just got to fine tune the synce and set idle mixture. If you need a diffrent muffler I just got a used set and only need the right side or you can have your old one patched. If you are interested in the left side exhaust when I get it I can send you a pic. Let me know.
     
  8. Altus

    Altus Active Member

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    The turning the bars causing the idle to go up? It's not the throttle cable - it's the choke cable (too tight) :wink: Don't ask how I happen to know that one. Betcha if you watch the little choke actuators, you'll see them move up.

    Now - as for not idling - as the others have said it definately sounds like some crud has made it though to the carbs. Do you have a fuel filter in the line? If not - now's the time to be adding that. Then it's time to pull the carbs and give them a thorough cleaning to get whatever gunk is hiding in the idle passages outta there. I'll wager a beer that fixes it right up.

    Lastly - muffler. No, not really a factor in the other issues. As for replacement, that's your personal choice :) My 2 cents -- I've had a MAC 4-into-1 system on my bike for about 15 years now (good gravy, has it been that LONG?) and the more I look at it, the more I wish I'd squirelled up the extra cash for the 4-into-2 system.
     
  9. railtramp

    railtramp New Member

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    clean carbs, inline fuel filter, bench sync, idle adjustment, slack on the throttle, looser on the choke . . . righteous. i imagine i'll post more pleas for help in the coming weeks, once it gets going. thanks for all the info and advice. as far as the mufflers, it is a 4 into 2 right now and i totally dig the look. mine is the right side as well, so maybe that's a pattern. expensive things, they are . . . again, thanks a lot!!!!!!!!
     

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