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1982 Maxim xj650 idle issues

Discussion in 'XJ Technical Chat' started by 82maxim650, Jul 19, 2012.

  1. 82maxim650

    82maxim650 New Member

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    Ok I need some help...

    I have a 1982 Yamaha Maxim xj650 that I picked up used with about 35,000 miles. I cannot get the idle where it needs to be. I have pulled the carbs and religiously cleaned them 3 times with carb cleaner spray and the dipping solution to no avail. I even replaced the pilot jets and needle and seat on all carbs with new parts. What happens is when the bike is cold it will start with the enrichment circuit (choke) all the way out but sputter at around 1k rpm if at all, usually just starts and dies. Well after a few starts this way I could get the bike to warm up and idle off choke around 1800 rpms if I play with the idle screw enough, but the idle is still all over the place. I could get the bike to idle down to ~1800 rpms but as soon as I give it gas the idle will shoot up to 4-5000 rpms until I turn the idle adjustment screw in to get it back to ~1800, if I go lower the bike just sputters out and dies, will do it at 1800 but takes a bit longer. Sometimes when the bike doesn't catch at 4-5000 rpms then it will take about 3-4 seconds for it to idle down. Another wierd thing to me is when the bike is warmed up and you push the choke knob all the way out it will act as if you just gunned the gas trying to redline until you push the choke back in. My next things are going to be check for vacuum leaks around the engine-carb boots and check the float levels in the carbs. Also when I do get the idle down, although it doesn't stay there and the idle is typically all over the place, I can take it for a ride and you wouldn't even notice there is an issue until you come to a stop.... PLEASE HELP....
     
  2. 82maxim650

    82maxim650 New Member

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    Side note: You do notice the idle when riding between shifts it will idle up to about 4k until you hit next gear. Also, I only replaced the needle/seat/washer on all carbs out of desperation but did not fix the issue, and the carb kits I bought of eBay don't seem to be correct?? My needle jets had a little filter/screen on the bottom and the new ones don't (can't put them on because the new ones are smaller outer diameter). Also it seems with the new ones the jet and needle sit lower??? Anyone else noticed this with these kits?
     
  3. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    Sounds like vacuum leaks and floats out of adjustment. Wet set floats and check for vacuum leaks. When was the last time valves were set? Might want to get a look at those.

    MN
     
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  4. moellear

    moellear Member

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    How far did you open the carburetor rack for this cleaning? If ya just dumped the entire rack (assembled) into the dipping solution, that's mistake #1. Now you have to be concerned the dipping solution didn't start eating away the remains of your throttle shaft seals.

    Check for air leaks and get the float levels set accurately (wet-method). And of course if valve shim clearances aren't in spec, you'll be chasing your tail until EVERYTHING is checked. http://xjbikes.com/Forums/viewtopic/t=14827.html

    BTW; a service manual of some type would be highly suggested if you do not have access to one yet. Ebay has them readily available and is well worth the investment.
     
  5. 82maxim650

    82maxim650 New Member

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    When I cleaned the carbs I only dipped the jets and needles and usual stuff into the cleaner, not the actual bodies themselves, I used carb cleaner spray and compressed air on those. I did have to end up replacing the o-rings on the main fuel nozzle on the fuel line also. Also when you guys say "wet" method do you mean while still on the bike? Can this be performed correctly with them off the bike and a temporary gas tank hooked up and having the carbs level? I do have the service manual and it states 3.0mm +/- 0.5mm on the float height just wondering where you measure for this, is it from the gasket mating surface down to the gas level in the tube?
     
  6. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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  7. 82maxim650

    82maxim650 New Member

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    Ok wizards,

    Just got the new intake manifolds on and still having issues, believe it has to do with air/fuel ratio and sync issues now. The bike is still having a hard time starting cold. With the enrichener pulled all the way out it will cough a couple times before catching, and warmed up I have no idle, when I adjust the idle stop screw I can get it to idle but it like to hang at 3-4k when I'm riding??
     
  8. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Get your valves in spec;

    be sure you wet-set the float levels accurately;

    set the pilot (mixture) screws at 2 1/2 turns out;

    then do your running vacuum sync, with the YICS blocked.

    But not until the valves are in spec.
     
  9. taptapindustries

    taptapindustries Member

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    How did you go? My bike has same symptoms. I suspect air leak, possibly around shaft seals, and or blocked primary jet/ passage way.
     
  10. Jetfixer

    Jetfixer Well-Known Member

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    Old thread but there are many variables. Did you do a full tear down taken carbs to church. What condition are your intake boots in ? Are you running PODS ( not recommended) ? If you are have you changed jetting? Have you checked valve clearance and adjusted? Have done a running vacuum synch of the carbs? All could cause problems.
     

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