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Mikuni xj550 maxim carbs

Discussion in 'XJ Technical Chat' started by moellear, May 20, 2012.

  1. moellear

    moellear Member

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    What do you guys use as a fuel level measurement tool to check fuel levels?? I'm stumped trying to makeshift anything to shove into the bowl drain hole... its making this mikuni carb level check a PITA!

    Hitachis (like on my 650) provide nipples to just put a clear tube on whereas the mikuni doesn't. I tried using just 1/4" plastic extension nozzle and shove it in there. sorta works but not effectively.

    Also, I've had a small dribble of gas continuously leak out the small vent hole, directly in the middle edge portion of a throttle opening side (carb to airbox side). Upon research, I found it had to be valve seat o-ring leak. So i went uptown and replaced them. Still a continuous minor leak coming out the vent tube hole which tells me I have a problem with either valve seat or float. But I can't measure the float levels accurately because of no nipple. Its all a PITA!!
     
  2. skyhawk

    skyhawk Member

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    I used an odd size clear piece of tubing left over from a battery acid pack, it was not used for acid. I put one or two wraps of black tape around it and it worked perfectly without any leaks on my 550 Maxim. You should be able to find some clear tubing at any hardware store. Remove your bowl drain screw and the tubing should fit snug inside the bore.
     
  3. MiCarl

    MiCarl Active Member

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    I've got a nylon hose elbow. I don't remember if I filed the barbs down on one side or if they got like that forcing them into the recess.

    Clear tube on the good end.
     
  4. moellear

    moellear Member

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    +1. worked a lot better & I appreciate the advice. I used 1/4" clear tube and did the same thing. If it leaked, it was minimal so I was happy to complete the float level check. took a long time & I was learning to be patient while putting up with the smell on my hands for 4 hours but I'm pleased with the results

    Now, I have 3 outta the 4 pilot mixture screws still with brass caps over 'em. Leave 'em alone? Feel like its not worth taking them out unless necessary because you know they were never screwed around with. Whaddya fellas think??

    Also, different topic but the tachometer cable spins slowly under low rpm numbers. I took the drill method only because the bike is not even capable of running yet, to check the cables & functionality. Seems like the needle itself is slow from the start but after 6~7k, it springs over to 12k really quickly. Any thoughts?
     
  5. skyhawk

    skyhawk Member

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    There is a thread on this site that talks about drilling a small hole in the plugs and then popping them out. I would just keep going into them and do it all. The idle circuits and all the rest. It'll save you future headaches knowing that it's been done, and it's not that hard to do. Your half way there, might as well do it all. Check XJ4Ever's "information overload hour", there is carb info there for you to read.
     
  6. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Go back and look at the exploded view of the Mikuni carb: http://xjbikes.com/Forums/viewtopic/t=31061.html

    If you didn't pull the pilot screws the carbs aren't clean; there's no way to have properly cleaned the pilot circuits with the screws still in place.
     
  7. moellear

    moellear Member

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    very much understanding fitz. just thought I'd pose the question and see what responses I get back. And I appreciate the exploded view of mikuni carb. While the carb rack is still on the bench, I may as well go thru it all now rather than fuss with assembly & disassembly later.

    3 other (un-related, sorta) questions: One being the tachometer needle mentioned earlier.

    Another one deals with ColorTune. Is there suppose to be two different sizes for this (the one Len has)? I bought one from a former xj member on here, which fits 14mm for 650cc head but just realized these plug holes are 12 mm for 550cc. Is there an adapter that will work?

    Last one deals with 14mm to 12mm thread since on the same topic about ColorTune adapter. Would anyone have available just an adapter to go from 14 mm to 12 mm (or 18mm to 12 mm) for a compression tester? I'm not worried about compression because the bike fired up on the day I bought it and seemed solid. I was shocked to hear it purr on that day I bought it (with choke obviously), after cleaning the carbs this past week. It'd be nice to verify psi though in the head, so if I could just borrow an adapter that would be great! I've searched high & low to find something and the few companies that could help me charge an arm and a leg, or else tell me to purchase a whole new kit. PM me if you could help me out!

    -Aaron
     
  8. moellear

    moellear Member

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    i'm tempted to tear apart the cluster.. anything to avoid or be careful with?

    also, bumping to see if anyone is capable of helping me out with an adapter for compression tester. haven't heard from anyone
     

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