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Weird Problems.. think carberutor related? (Rickcomatic?)

Discussion in 'XJ Technical Chat' started by dusty, May 2, 2011.

  1. dusty

    dusty New Member

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    Hey Guys,
    Bought this bike a couple years ago and rode it about 1,000 miles home. It was a scary trip but I made it! Anyway it is a '81 xj650 shaft drive.. when I first got it I cleaned the carbs until they seemed spotless and put them back. Trying to get her back on the road and I noticed this season it is still giving me the same problems it always has.
    Usually starts up fine with no choke but will bog when I give it any throttle, sometimes will work alright for a few seconds if I turn the throttle really slow and sort of let it catch up. I have never sync'd the carbs but I have run a bottle of seafoam in it which seems to help a little.
    To put it simply if I am out riding it and I hit a stop sign, I have to turn the choke up about half way then let the engine start to rev then throw it in to gear and it seems to work alright. If I didn't use the choke it would just kind of sputter down the road, but once I put that choke on it seems to "kick" in and the bike takes off.
    Anyway, I work down in Chelmsford, MA saw that RickComatic knows a lot about these carbs and bikes in general..would glady throw some money or spare parts your way if we could go through the carbs together sometime? If it's not the carbs the only other thing I can think of is the far left front side of the valve cover has a semi stripped screw hole in the engine head that a little oil seeps from; maybe I am losing compression somehow?

    Sorry for making this so long, thing has been driving me a little crazy! If anyone has any ideas please let me know!
     
  2. yamaman

    yamaman Member

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    got a colortune plug? if not, get one, you'll be happy you did, no doubt. I had the same problem and didn't find the cause until I bought a colortune. turns out, my Brand New Dyna coil was failing above idle rpm. I would have never known without the tell tale window in the colortune. It was Ohming out perfect.

    do you have a vacume gauge? probably not since you haven't sync'd them. you might have a vacume leake around the intake manifold boots that bold to the cylinder. Mine also looked perfect, until I removed them, you simply can't see until you remove them. Most people are skeptical about it since there are horror stories about the heads breaking off. I say, if the bike isn't covered in rust, then do it. But if it is rusted bad, have plans for a removal procedure. I think there are some on this site. Good luck, let us know
     
  3. iwingameover

    iwingameover Active Member

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    If you didn't do an idle adjustment and synch you'll need to start there.

    Also, have your valve clearances been checked?

    What do your spark plugs look like on the business end? Good in focus pictures can help us help you.

    You will not loose compression out a valve cover bolt.

    Choke on these bikes actually adds fuel and is properly called an enrichment circuit. "Choke" usually restricts air flow.

    Your idle mix is lean and by adding the fuel from the enrichment circuit you're giving it what it needs to make the transition to the main fuel jets.

    The colortune will certainly help in this case.

    You can make the synch tool for about $4. search the site I know I've posted my method before.
     
  4. dusty

    dusty New Member

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    Re: Weird Problems.. think carberutor related? (Rickcomatic?

    Thank you guys for the help. It looks like Rick may help me out and let me use his color tune (these are just plugs that change colors to show you which cylinder may have an issue right?). Will look into the homemade carb synch tool...how do they get out of synch anyway? Sorry for all the dumb questions!

    also spark plugs all are slightly white (lean?) on the electrodes...
     
  5. yamaman

    yamaman Member

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    well the compression changes w/ age and passages may begin to get built up crap on the inside, like cholestoral in arteries, and valve clearances change minutely, so vacume that gets pulled from one hole to another changes slightly over time.

    I think!

    let's see if I get yelled at for that one lol
     
  6. dusty

    dusty New Member

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    Re: Weird Problems.. think carberutor related? (Rickcomatic?

    makes sense to me yamaman... i hadn't even considered that. Crossing my fingers that it's just a carb thing :) I haven't checked the valve clearances either.. I don't have any feeler gauges; sort of learning this stuff as I go! Hopefully Rick will be able to help me out after hes done laughing at this bike of mine lol
     

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