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Yamaha XJ 550 4V8 Trouble Starting Motorcycle (Philipp's ongoing troubleshoot)

Discussion in 'XJ Technical Chat' started by PHIdet, Oct 13, 2019.

  1. Jetfixer

    Jetfixer Well-Known Member

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    One thing you should try , turn the idle knob in several turns and see if it will start or at least chug, if it is not pushing against the butterfly plates will not open , hence no fuel into cylinder. You have stated you were trying brake cleaner to try to start , starting fluid is best to use. You can also do a bench synch, I take two business cards cut in half , put one piece under each butterfly plates , try pulling card out with slide drag if to much or not enough starting at carb 1 turn synch screw in or out till you get a slight drag ,move on to carb 2 , and carb 4 , carb 3 is controlled with the idle knob . If you do this right , hold carb rack up to a strong light you will see a slight crescent moon at bottom of butter fly plate. From what you have stated to me it is fuel related problem , if you adjusted valve clearance that will help . Good luck.
     
  2. PHIdet

    PHIdet Member

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    Hey guys,

    After a rather long hiatus I finally got back to getting the bike ready for the season - as bad as it is, Corona afforded me plenty of time to work on the bike.

    After going over the carbs multiple times and having figured out all the electronics, I finally got the bike to start.
    Unfortunately, it revs really high right from the start, around 3000 rpm.
    The high revs are consistent, and I can't make out any air leaks (I replaced all the rubbers), and I doubt it's got to do with any clogging in the carbs since I was very minute in cleaning them

    @XJ550H I found the mixture screws, but I'm guessing either I or the previous owner screwed up the setting.
    What's the standard amount of turns for these, and do they influence idle speed?
     
  3. PHIdet

    PHIdet Member

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    Okay I just figured it out, 3 minutes after posting this.
    Turns out, clever me failed to notice that the idle screw was turned in way too high.

    Concerning the mixture screw, I'd still love to know how many turns they're supposed to be out.

    Is there any way to post videos in this forum?
    I'm noticing a metallic, rattle-y noise coming from the engine, as if a key is touching the vibrating frame.
    While the bike is running, the oil level in the lower half between the two lines on the little oil screen below the transmission, so I'm guessing there's enough of that.
    The bike hasn't run in well over two years, so maybe the noise is gonna stop once it's all lubed?

    I was also thinking valve clearances. I just checked those, but that was before the bike even fired up for the first time, so I'm not sure how reliable those measurements were.

    Any other suggestions?

    Cheers
     
  4. hogfiddles

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

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    -Did you ever do a running sync?

    Check your collector box heat shields....they can get loose and start to rattle. Also, look to see if one of the relay rubber mounts has broken.if so, it may be hanging down and vibrating against something.
     
  5. PHIdet

    PHIdet Member

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    Thanks, I will check that.

    Here's a video of the rattling, it can be heard rather well around 25s

     
  6. hogfiddles

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

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    Did you replace shims to get correct clearances yet? ( did you do you clearance measurements with a COLD engine)

    Did you do a running sync yet? Sounds like it’s not synced yet....

    and from my view, it sounds like a loose cam chain too.... have you done anything with the cam chain adjuster?

    also just as an aside, does the sound go away when you shift into gear and let the clutch out?
     
  7. PHIdet

    PHIdet Member

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    Thanks a lot for the input.

    Yeah I already replaced the shims to have the valve clearances up to specifications, but I did that with a cold engine. I knew I would have to redo that at some point, but I wanted to take closed valves out of the equation.

    I did not yet sync the carbs at all, I'm pretty sure that's why it's running on the rough side.

    Ew, cam chain problems would suck. Does the XJ 550 have a spring loaded adjuster?

    Concerning your suggestion with the gear, I'm gonna check that tomorrow, I didn't check that yet.

    As a side note, I noticed that there's fuel dripping out of mufflers on the joints on both sides, so I'm assuming it's running fiercly rich. Is there any smart way of properly tuning the carbs without any special equipment?
     
  8. Huntchuks

    Huntchuks Well-Known Member

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    What do your sparks plugs show?
     
  9. XJ550H

    XJ550H Well-Known Member Premium Member

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    mixture screws set at 2-1/2 to 3 turns from soft bottom.

    the 550 has a springloaded cam chain tensioner it is under the carbs a bolt with a lock nut.
    you remove the crank side cover left side of bike turn that square nut counter clockwise untill the pointer points at the C mark

    losen the lock nut then losen the bolt
    you should hear the adjuster pop forward if it was real loose
    upload_2020-4-23_17-13-30.png

    retorque bolt to spec torque nut to spec replace side cover your done


    with oil when bikeis on center stand add oil an ounce at a time untill there is a little bubble left at the top of sight glass and set rpm to 1100rpm this will help quite down the primary chain
     
  10. hogfiddles

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

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    I’m glad to hear you did them clearances already, and YES, you DO do it when the bike is COLD. So you should be good there, as long as you did it right.
     
  11. PHIdet

    PHIdet Member

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    @Huntchuks I'm gonna check them later, I'd be surprised if they weren't pitch black. I'm running the bike off a rudamentary gas tank and I could watch the bottle emptying, that's how much gas it was chugging. Are there any other reasons why the bike might spit out unburnt gas?

    @XJ550H Great, thanks for the walkthrough. I'm gonna do that later. Concerning the oil, am I supposed to top off oil while the bike is running? I just wanna be careful as to not overdo it with the oil.

    @hogfiddles Oh that's interesting, I thought you were supposed to adjust valve clearances with a warm engine. Oh well, I take it :D


    Down the road I want to replace the clutch plates and springs. A shop stated on the most recent service report that the clutch was slipping or not disengaging properly.
    Will I have to drain the oil before opening the clutch case, or won't there be any oil coming out while the bike is on the side stand?
     
  12. a100man

    a100man Well-Known Member

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    Bike sounds ok to me but cam chain tensioner adjustment won't hurt (easy too)

    Oil level check when engine off and 'rested' 5 minutes.

    cheers
     
  13. PHIdet

    PHIdet Member

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    Okay so I did the cam chain tensioner adjustment, though I did not hear it click at all, and the engine still sounds the same, running.

    I'm having trouble starting without starting spray after it's been sitting for a while.
    Also, as I mentioned before, I feel like it's eating gas like crazy. I'm flooding the bowls and keep a good bit of fuel in the fuel filter, and after having it run for ~ 30-40s the fuel filter is empty. Not sure if that's normal for that bike.

    Engaging the clutch and going into first gear didn't change anything about the sound either.

    The spark plugs are not at all what I expected, they're pretty white with a tinge of brown/yellow.

    There's also gas still dripping out where the mufflers meet the heat shields after it ran for a while.
     
  14. Huntchuks

    Huntchuks Well-Known Member

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    You stated you have cleaned the carbs well but did you make sure you cleared the enrichment circuit jets pressed deep into the side of the float bowls?
     
  15. PHIdet

    PHIdet Member

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    I did, I knew I had to look out for them.
    Also, playing with the choke does not help.

    Does the carb mixture setting affect the cold start and idling of the engine or does it only come into effect when riding?
     
  16. hogfiddles

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

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    Mixture screw primarily affect the IDLE mix. The enricher enrichens the fuel mixture for cold starts.

    once you’re rolling on the throttle you are rolling on to the main jet... and THAT mix is residually influenced by everything else
     
  17. PHIdet

    PHIdet Member

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    Gottcha, thanks for clearing that up for me. So I'm gonna set the fuel mixture screws at 2 1/2 - 3 turns out, right?

    I took the carbs out once more, just to make doubly sure the enrichment circuits were clean.
    While I'm at it, I'm also gonna do the bench sync that you advised, @hogfiddles .
     
  18. hogfiddles

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

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    Yeah, about there for a starting point, then colortune and running sync. The 550 may end up more like 4- 4.5 turns out, too. The 550 is finickier than the 650/750’s
     
  19. PHIdet

    PHIdet Member

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    So there's no 'home made' alternative for fine tuning the mixture without colortune?
     
  20. Mjolnir

    Mjolnir Member

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    There is: ride the bike, pull the plugs, adjust, ride the bike, pull the plugs, adjust...you’ll never get it quite right though.

    Trust me: I didn’t want to buy the tool because it was $70, but man does it make it easier diagnosing problems and if you ever go to sell your bike, sell the tools along with it and get your investment back. I just bought the tool 2 weeks ago through chacal and it’s helping me get my rich run I g bike back on track. (Morgan Carbtune Pro helps too but that’s easier to make but well worth the $117)
     

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