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Difficulties starting and bad throttle response

Discussion in 'XJ Technical Chat' started by beardking, Oct 20, 2006.

  1. beardking

    beardking Member

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    I'm having problems with my bike again. It ran fine when I first bought it, then one day I went out to start it and it would crank without a problem but just wouldn't start. I replaced the plugs (as suggested on here) and all was good. Then about 2 weeks later I was out riding and it started sputtering and hesitating and then finally died and wouldn't start again. Finally got it home, replaced the plugs (since it worked before) but it did nothing. Ended up replacing the fuel filter and it started right up. I thought all was good in the world until I actually took it out for a ride. Started hesitating and dying again. Limped it home and have had a hard time getting it to start since. Got it started tonight, but it just wouldn't idle right. At first, I had the choke on and it started up and I let it warm up for a good 2 minutes then slowly brought the choke down. Got it to idle at about 950 or so but the throttle response was real sluggish. Then it jus kept petering off. Now I can get it started sporatically, but just about the second I give it throttle, it dies.

    I took the plugs out and all but one looks fine. The #1 plug has a heavy carbon coating like that one cylinder is running rich. I just got my Haynes manual tonight, but I haven't quite figured out how to adjust the mixture without taking the carbs off.

    Any suggestions or help would be greatly appreciated.
     
  2. RickCoMatic

    RickCoMatic Well-Known Member

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    Search the web for a ColorTune Kit on sale. Buy it! Use it.

    I >> USED << to think you could tweak the screws until you had a real nice mixture happening and a decent idle to go along with it.

    Until I ColorTuned my bike with a Kit I borrowed.

    My Max runs so good .. ColorTuned .. that I can get off the bike, pull out the bunched-up briefs, have a smoke, secretly gloat about nobody else I'm riding with, being able to let-go of their throttles, without their 20-thousand dollar bikes stalling-out.

    Buy yourself a ColorTune Kit.
    ColorTune ... IS the last word of fine-tuning.
     
  3. beardking

    beardking Member

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    Rick, can you tweak the screws with the carb on the bike. Excuse my ignorance, but this is my first bike, so I'm getting to know it all still.

    Does it sound like it's a mixture issue to you guys?
     
  4. Captainkirk

    Captainkirk Member

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    OK, Rick, I can't stand it anymore-
    What in the h-e-double hockey sticks is a Colortune?
     
  5. RickCoMatic

    RickCoMatic Well-Known Member

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  6. Hvnbnd

    Hvnbnd Active Member

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    Beardking, sounds like even though you have 1 cyl running rich, that you may have a fuel supply problem (starvation)?

    I personally have worked tuning engines for many years, was even an a&p mechanic and had never used a Color Tune, but since I bought and used mine, I must say that I am sold and will never try to tune a multicarb engine without one.
     
  7. Captainkirk

    Captainkirk Member

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    You were (are?) an A&P? Man, this little world gets smaller all the time!
     
  8. Hvnbnd

    Hvnbnd Active Member

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    Captn, been to school and was certified ready to work.
    Then life took a different path, I became a Phx Fireman.
    So how did I come to be working in a powerplant?
    Been out here over 24 yrs!

    Never say never!
     
  9. Polock

    Polock Well-Known Member

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    Beardking try the drain plugs on the carbs ,and see what comes out, then let your conscience be your guide
    you should pull the petcock out of the tank and make sure it’s clean too
    if you do start spinning mixture screws count the turns in till they just bottom so you can return them if need be 1 ¾ is a ballpark setting I think
    watch the choke plungers, see if they all close when the choke is off
    I think your need for a colortune is down the road a way
    happy motoring
     
  10. beardking

    beardking Member

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    Polock, I hooked up a piece of clear tubing to the drain plug on #1 and 2 carbs and unscrewed the screw and was expecting a decent flow of fuel, so I could check the level of the float. What I got, instead was a mild dribble that would barely fill up the u in the tube, let alone actually come up to level (it was below the bottom of the float bowl.

    Any suggestions on why this was? Oh, and I finally got the dang thing started last night. Had to blow a crap load of starting fluid in it to get it going, but once I did and let it warm up for quite a while it seemed to do ok. Still not confident it's not going to strand me again.
     
  11. woot

    woot Active Member

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    How far out did you turn the screw?

    It should have flowed quite a few teaspoons... that little? well I guess a low float - although I'm not sure that's consistant with running rich.

    What colour was the gas? Did it have a lot of crap in it?

    When you drain the carbs, put it on prime, let it sit for a minute and do the 3 second crank 10 second break until she coughs. You may also need to keep a battery charger near by. A weak battery will die very quickly when it's turning the bike over... the voltage will come back up if you let it sit for a minute.

    ColourTune and carbsticks... awesome inventions. Sync the carbs so that they all have the same vacuum, and adjust the mixture with the colour tune so you get nice blue flames in all 4. Once that's done she'll purr.
     
  12. woot

    woot Active Member

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    Hrm - other things that can cause rough idle:
    - valves
    - weak battery
    - pinched fuel line (more apparent at larger throttle openings)
    - bad gas
    - dirty carbs
    - poor carb balance
    - mixture wrong
     
  13. Polock

    Polock Well-Known Member

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    beardking, did anything besides gas come out of the hose?
    i was thinking catch the gas on a clean rag to check for dirt in the bowls
    the floats diden't get out of whack overnight by themselves
    but some dirt in the float valve could have one cylinder running real rich
    maybe check the hose from the engine to the petcock for leaks this could make the petcock trickle instead of flow
    there is another way to check the petcock but i don't want to tell you to suck the little hose and see what come out the big one :)
     
  14. beardking

    beardking Member

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    Now Polock, that's just not right. ;-)

    As far as the drains go, still not sure what the deal is with them. The gas that came out of them was a little darker than I imagine it should be, but I didn't have any fresh gas to compare it to. It's still only a trickle, but I'm thinking I may have a clue as to why it's just a trickle and the issue with my bike in general.

    Last night when I was trying the drain plug thing, I had moved the petcock to PRI (getting desperate). I thought that I had moved it back, but I hadn't. I ended up getting the bike started, road it up and down my block a couple of times and it ran fine. Came back and realized that I had left it on PRI. Wondered about that and switched it back to ON. Killed it and started it a few times and it did fine. Went out today, started it (still ON) and it started fine but ran rough. Let it warm up a bit, killed the choke and tried giving it a little throttle and it died. Looked around, had no idea what was wrong, then remembered the petcock issue last night. Put it back over to PRI, gave it a bit, cranked on it a bit and it finally started and ran fine again.

    I'm thinking that my petcock is toast. Gonna order one tonight, if I can find one in stock. Hopefully it'll be here by the time I get back from deer hunting and I can work on replacing it while I'm enjoying the rest of my vacation.
     
  15. woot

    woot Active Member

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    Certainly the petcock could cause fuel delivery problems. There is also a secondary problem in the blackened sparkplug. Once it's running properly again maybe you'll be better able to diagnose that... maybe it would disappear as just a strange symtom.
     
  16. beardking

    beardking Member

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    Yeah, I'm thinking once I get the petcock flowing freely, then I'll be able to get the bike running long enough to actually check things out. Anyone have a colortune they want to send me for free. ;-)
     
  17. kbarmansr

    kbarmansr Member

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    Most often in this situation the petcock is involved in some manner. Either a bad vaccum causing starvation at higher RPM's, or not working properly and there is no fuel delivery. From my experience with these bikes I have found that if there is a no start or rough idle problem it is usually fuel supply problems. This I have learned is now my first check. I have ran into this problem several times and it always heads back to the petcock. Not to say that something major or a carb rebuild isn't in order for some of these bikes, but mostly fuel starvation caused by a bad or leaking vaccum or petcock.
     

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