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need advice!! HELP!

Discussion in 'XJ Technical Chat' started by xj650jeff, May 22, 2013.

  1. xj650jeff

    xj650jeff New Member

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    HI all,
    Cleaned carbs two years ago when one cylinder wasn't contributing. Using the awesome guide on here it went well and bike ran better than it did in years!

    Last year I only put about 30 miles on it; busy summer.

    This year it ran like crap. I didn't use any Stabil or anything in the gas over the MN winter; so I cleaned the carbs. Lots of gummy stuff but no obvious blocked jets. Put back together.

    Still doesn't run right. Sounds good at high RPMs but at lower is very sluggish and often dies when I hit the throttle. Here are the troubleshooting things I've done:
    -drained old gas out of tank and replaced with non-oxy fuel. I did this right after cleaning the carbs

    -checked inline fuel filter

    -with engine running, I unplug sparkplug on cyl 1 and engine sounds about the same. When I unplug any of the other three plugs the engine sounds significantly different or dies.

    -I switched the sparkplugs in cyl 1 and 2 and repeated the above. Same result.

    -the exhaust coming from all four cylinders heat up so something is burning in all of them.

    -With the plug out of cyl 1, I put my finger over the hole and hit the starter. There does appear to be compression.

    There is spark going to cyl 1, but is it possible there is a partial issue with the electrical (not enough current going there??)

    Any ideas?
     
  2. fintip

    fintip Member

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    It's possible that carb wasn't cleaned well enough. If it was one of your coils, you'd have two cylinders not firing. Timing and air should be fine, electrical problems would almost certainly be two cylinders (and you have spark), so it is most likely fuel.

    Spark plug cap and cable are the other things to check, but those don't often cause problems.

    I'm still a little thrown off by you saying all four get hot, though, as everything else points to a non-firing cylinder.

    Was it the same cylinder that wasn't contributing last time?

    Might want to make sure you've properly adjusted the pilot mixture screw as well. And did you sync them yet? Just bench sync, or proper sync? Ever done your valves?
     
  3. xj650jeff

    xj650jeff New Member

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    I believe it is the same cylinder that caused problems last time, which is why I cleaned the carbs first. I never have done the valves and I am sure hoping that isn't the issue.

    So with the coils/plug wires, you should either get spark or not get spark. Shouldn't be an inbetween correct?
     
  4. xj650jeff

    xj650jeff New Member

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    ...and no I didn't mess with mixture screws or syncing.
     
  5. Ground-Hugger

    Ground-Hugger Member

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    Well you need to DO the valve shims. You need to DO a vac sync. AND you need to adjust the fuel/air mixtures. Cleaning the carbs alone will not make the bike run right. I know I've been there.
     
  6. moellear

    moellear Member

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    a LOT of us have. and now that its riding season, people wanna hop on their bikes and go. No shortcuts though; you'll have bigfitz all up on your @S$ with a list of things for you to do. For starters, the valve shim clearances. Its not gonna matter if the carbs are cleaned, if the valve shim clearances are outta specs.

    You are probably smart enough to do all the prep work to get the bike running well. No shortcuts, do the things we've mentioned, and ask for assistance at any time! Then I bet you'd have a well running bike. Yes, either you have spark or you don't have spark.
     
  7. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Exactly. START by getting the valves in spec, then do a compression test so we know we're not trying to tune a damaged motor.

    Then once you've properly serviced the carbs and wet-set the float levels you'll be able to sync them.

    The route you're taking right now will simply get you nowhere fast.
     
  8. xj650jeff

    xj650jeff New Member

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    Any guides on how to check the valves? I didn't see any one here.
     
  9. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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  10. fintip

    fintip Member

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    Hey fitz, when ya gonna fix that 650 seca already?
     
  11. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    heh heh.......his will probably be ready AFTER mine is ready------and I"m in no rush. LOL

    Dave F
     
  12. losifer

    losifer Member

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    Where in MN are you? If you're in the Twin Cities, I'm sure it wouldn't take much to get one of us to come out with our valve shim holder and help you measure your clearances.
     
  13. tumbleweed_biff

    tumbleweed_biff Active Member

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    Remember that you have a channel connecting the fuel input of all 4 cylinders together between the carbs and the intake valves. If one carb is not providing (proper) fuel, the cylinder will still get some because of that connection (which is why you have to use a YICS tool or equivalent to properly sync your carbs.) Thus, even if carb 1 is not producing, cylinder 1 will still get fuel and will still get warm, just probably not as much as the others ...
     

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