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Choke?

Discussion in 'XJ Technical Chat' started by badtazboy, May 8, 2007.

  1. badtazboy

    badtazboy New Member

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    Hello all. I am on the rebuilding of my 1st bike a 650. I have redone the motor and cleaned the carbs. Have done every carb scenario in here except the sync. My bike starts and runs perfect but when I hit about 45-50 mph the bike just bogs down and nothing will make it go.
    Until the other day I was messing around and at 45 I opened the choke and … bam I had all the power to keep up with traffic.
    Question, is this normal?
     
  2. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    No, it's not. You're running lean, the choke on these bikes is actually a fuel enrichment device (adds gas rather than restricting air). So either your jets aren't zestfully clean, or they are too small (if the bike has any intake or exhaust mods, both of them tend to increase AIR flow through the engine and thus leans out the mixture). If the bike has no air-flow-enhancing mods, then it's time to clean again and check to make sure that you have the proper sized jets in the carbs. You didn't mention what year/model 650 you have, with that info provided we can tell you what size jets you should be running.....
     
  3. geebake

    geebake Member

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    Definitely not normal. Sounds like the carbs need synched.

    I recently synched the carbs on an XJ700. Prior to synching, the bike would act really strangely when it was on choke. Racing to really high rpms, wouldn't accept any throttle input. Wouldn't idle without choke.

    Not exactly the symptoms you have, but related I think. Synching completely straightened it out.

    Greg
     
  4. badtazboy

    badtazboy New Member

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    Little more information: it’s an 81 XJ650 no mods. The bike was given to me after sitting out in the elements for many years. Would not turn over, redid the motor and carbs.
    I did mess up one needle jet and got a used one from a salvage yard (the bike was the same).
    There is a guy locally that will sync my carbs for $50. I have read posts in how to make a sync tool but I am not that mechanically inclined to build things.
    Still want to ride for the time being, will riding with choke open affect the motor in any way?
    Trying to hold off on bring outside help until I finish my other bike (81 XJ550)
     
  5. geebake

    geebake Member

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    You can get a set of Synch gauges from JC Whitney for $50 and do it yourself. It's pretty easy.

    The bike will be running rich if you leave the choke on. You'll foul the plugs fairly quickly and I would think you could cause some carbon build up. I wouldn't do it, but I have to admit that I've done worse.

    Is your bike a Maxim or a Seca.
     
  6. badtazboy

    badtazboy New Member

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    Jc is a good call since I will also working over another one.
    BTW it’s a Maxim, the other one is also a XJ550 Maxim
     
  7. badtazboy

    badtazboy New Member

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    I do have a compression checker for automobiles could that work?
     
  8. KiwiXJ750D

    KiwiXJ750D Member

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    I had the exact same thing happen once it was a plug not firing?! Don't know if that is your problem as my idle was a bit off too. Was testing a set of carbs, back to EFI now :).

    Checked your float levels?

    Build your own sync tool: http://xjbikes.com/Forums/viewtopic/t=4191.html

    Car compression tool works. You have to be careful to avoid a shock from the leads. It is also rather tricky to hold it in place too.
     
  9. badtazboy

    badtazboy New Member

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    Have done the floats they are at the right level.
    Sorry I was confused, I have an automobile vacuum tester ... would that work?
     
  10. KiwiXJ750D

    KiwiXJ750D Member

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    Rick has a guide http://xjbikes.com/Forums/viewtopic/t=2132.html on using a automobile vacuum tester but I found the method I posted above works just fine and is simple.

    I don't think this is your problem though.
    Have you pulled your plugs and had a look at the colour and condition of them?

    Does the bike rev out in each gear or does it get to a certain RPM and then bog?

    Don't run it on choke all the time, too rich and will "wash" the oil off the bores.
     
  11. RickCoMatic

    RickCoMatic Well-Known Member

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    Yes.
    Build a restriction device. A carb cleaner red tube through a hose union filled with epoxy ... so the hose union ... when used to join two vacuum hoses will be restricted to the diameter of the red tube.

    4 long length of vacuum hose.
    4 golf tees.
    Put the hoses on the manifold ports and run the ends to a piece of cardboard and keep the 1,2,3,4 organized.
    Golf tees in all four.
    Run engine and get idle 900 - 1200
    Pinch-off line to 3 ... pull Tee ... plug-in vacuum guage get:

    BASELINE Vacuum for #-3
    3 does not have a sync screw ... 3 is the baseline carb ... all others will be set to match 3

    Mark Baseline #-3 Vacuum on the face of the gauge with a sliver of masking tape at the point of where the fluctuating indicator shows highest vacuum for 3.

    Make sure the tape isn't going to fall off ...

    Plug 3
    Measure 2

    Now ...
    Measure Vacuum of #-2
    Mark - 2

    Plug 2
    Measure 1
    Adjust #-1 ~~> to MATCH Vacuum level of #-2 ~~> by Adjusting the Sync Screw attached to #-1.

    Plug 1
    Measure 4
    Adjust #-4 ~~> to MATCH BASELINE (#-3) ~~> by Adjusting the Sync Screw attached to the #-4.

    Plug 4
    Connect and read #-2
    Adjust #-2 ~~> to MATCH BASELINE (#-3) ~~> by Adjusting the Sync Screw attached to the #-2

    The #-1 Carb is Synced AND Attached to #-2 and will be adjusted to the BASELINE when the #-2 Carb is adjusted to MATCH #-3.

    YICS Engine???
    Fabricate Tool.

    Here's your own personal, handy and disposable YICS TOOL.

    I don't care what Material or Lubricating Agent or what variation you might add to make this different in any way ... the concept is mine. Therefore, I am naming The Concept.

    "RickCoMatic's YICS Stuff" (and a better name to be added later)!

    Sharp hook the end of a length of wire coat hanger.
    Snag the well-trimmed end of a length of COTTON Clothes Line to the wire.
    Wrap the splice with a bit of DUCT TAPE to prevent the Clothes Line from coming off the wire.
    Undo BOTH Caps on the openings to the YICS PASSAGE.
    Pass the wire through the passage and prepare to draw the Clothes Line through the YICS Passage.

    After the splice and taped end are started-in ... begin saturating the Cotton Clothes Line with MARVEL MYSTERY OIL. (MMO)
    As a cleaner, a fire-proof agent, top cylinder lube and most importantly ...
    A VAPOR BARRIER!

    Pull the MMO saturated clothes line through the opposite side.
    Leave several inches exposed.
    Cut.
    Stuff the MMO saturated clothes line back in the YICS PORT and replace end PLUG.
    Stuff the open side with MMO saturated clothes line.
    Replace plug.

    Balance Carbs.
    Set Mixtures.

    Remove "The RickCoMatic Stuff"

    I'll come-up with a better name for it later.
    Cheap.
    Clean.
    Safe.
    And good for your engine!

    100% Cotton Clothesline -- Only.
    Marvel Mystery Oil -- Only.

    Give it hell ... you can sync carbs DEAD ON ... it just a bit awkward and time consuming.
     
  12. badtazboy

    badtazboy New Member

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    Ok had the carbs synced and still having the same issue. But now I am back firing for the left side only. I have also noticed that my pipes on the right side seem to be discoloring while the left is still shinny.
    Next help please?
    I’m thinking it’s almost salvage yard time :cry:
     
  13. RickCoMatic

    RickCoMatic Well-Known Member

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    At the end of the rainbow is your ... (I don't know anything about your bike ... because there's NO Thumbnails in the Signature section) ... getting tuned-up, by you or the lucky guy who picks-it-up cheap; after you give-up and quit on it.

    Because I have no clairvoyant skills, what-so-ever ... I can't possibly know what you have not done yet that will bring your bike another inch closer to running like Hornet Jet Aircraft.

    Carbs perfectly cleaned?
    Clunk tested?
    Haynes "Wrong Jet" reversed checked?
    Bench synced?
    Bench Pilot Mixture Preset?
    Battery charged?
    Compression tested?
    Spark present tested?
    YICS Passage stuffed?
    Run bike.
    Set idle.
    Sync.
    Set idle mixtures.
    Tweak idle mix for best color or best idle.
    Un-stuff YICS.
    Adjust idle to 990rpm.
    Wash.
    Ride, ride, ride, ride, ride, ride.
    ___________________________________________________
    Year - Model - Mileage - Stock? - YICS-Y/N - (Problem)
     

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