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1980 XJ650 Carb Tuning

Discussion in 'XJ Technical Chat' started by Dave30, Oct 7, 2020.

  1. Dave30

    Dave30 Member

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    So I looked at the battery closely, the one that the parts place said fit my bike has the positive on the right. I'm an idiot, no wonder the fuses were popping. SO I got one with the correct terminal placement. There is still an issue even before I switched the batteries which I'm hoping is solved by charging the new one I got. The bike would barely turn over to the point the motor would stop moving and you could hear liquid, presumably fuel being squirt in the carbs or around that area. I will try again when the new battery is charged and installed but i hope nothing else has died on this thing.
     
  2. Minimutly

    Minimutly Well-Known Member

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    Yes you are an idiot, but the consequences of your actions may not yet have shown themselves yet. The tci is transistor - the "t" in tci. I suspect it won't have enjoyed being reverse polarity'd.
    And to go back up to your comment on " "you could hear liquid.....". This was NOT liquid, there is nothing to squirt it, it was your starter crying in distress, either from not having enough current to drive it, or not getting the available current into the rotor. Most likely due to low battery, but maybe it needs looking at?
     
  3. Dave30

    Dave30 Member

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    I'm charging the new battery right now so I'm hoping it was simply the low battery. Luckily the fuses were popping instantly when I was hooking it up backwards so any damage, if any, was minimal. I rode this thing around right before I took the top end apart and replaced the brake stuff and even then it would sound lazy when starting so I'm hoping it was simply a low battery. We shall see tomorrow... Idiot, out.
     
  4. Minimutly

    Minimutly Well-Known Member

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    To be fair your parts supplier tee'd you up to make this mistake, but it was still a fundamental error, hope you haven't fried your tci...
    Good luck with it.
     
  5. Dave30

    Dave30 Member

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    Alright, so I charged the battery, mounted it and tried to start the bike. It was still majorly sluggish, and ultimately the engine stopped turning, now all that happens is the neutral and oil level light come on. This behavior was visible BEFORE I even switched the polarities like a dumb. So at this point its got to be electrical right? OH also new development, I tried to use a rubber mallet to tap the back end of the fuel tank to seat it onto those rubber studs and now there's a pinhole in the back corner of the tank leaking fuel. Hidden rust in the bottom of the tank perhaps. If so is that even fixable or would it be easier to get a new fuel tank as a whole?

    Edit: I don't think this is fixable nor would I want to put some sort of temporary fix on the tank just to have it come apart later or worse, clog all the fuel systems I just replaced/cleaned. At this point I'm at a decision to get a new tank and hope the work I've done to it thus far makes it run or abandon the project and sell the bike. I'm just unsure now.
     

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    Last edited: Nov 1, 2020
  6. Dave30

    Dave30 Member

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    Ok. I am going to attempt to remove the rust on the inside of the tank and seal it with stuff that says it seals pinholes. Its cheap and hopefully it works. I also found a new starter solenoid for 10$ I will try when it comes in. I'm going to work on my other bike next week, this maxim is an emotional rollercoaster.
     
  7. The Blackwatch

    The Blackwatch New Member

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    Pull your starter motor and clean it. Checking your carbon brushes and your insulating washers. This may be the cause of the previously sluggish turnover of the bike and the not starting but have neutral and oil light issue you have now.
     
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  8. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Only one fuse is 20 amps (the main). All others are 10 amp.

    What brand of tank liner are you using? Kreem is total crap. Don't waste your money on anything other than Caswell or Red Kote. Use masking tape on the hole so the liner doesn't leak out.
     
  9. Dave30

    Dave30 Member

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    So I used a small patch on the outside and put a bit into the hole, forgive me it was JB Fuel Tank weld. Its cured over 24 hours now and appears solid, its also ugly but its at the back corner of the tank where you really wont see it. The cleaner, rust remover and sealer all came together from KBS. I went with that because everyone has their own stuff they use and process and I figured id have less of a chance to screw something up if I went with a package system.
     
  10. Dave30

    Dave30 Member

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    I'm working on the tank right now, I got some Red-Kote since it seems well liked. Otherwise I installed the new starter solenoid and now the bike clicks audibly when the ignition is turned but just the Oil light comes on. So I cleaned the side stand switch, bike is in neutral, clutch is pulled out of habit and still just a click. I'm putting the battery on a charger right now just to make sure it didn't die in a week of inactivity but that seems unlikely. Before I did anything electronic the bike barely turned over and ultimately stopped altogether. New solenoid happily clicks away but nothing happens afterwards.

    Edit: Solenoid bypass does nothing, perhaps the starter motor being gummed up is why it gradually stopped starting over time.
     
    Last edited: Nov 11, 2020
  11. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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  12. Dave30

    Dave30 Member

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    Already pulled and rebuild kit ordered :) going to seal the tank once it dries out hopefully tomorrow.
     
  13. Dave30

    Dave30 Member

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    Awesome news, rebuilt the starter motor with the kit I bought. The copper was completely black along with the rest of the armature and upon cleaning I saw the copper was in pretty rough condition. I sanded it the best I could to make it smooth and replaced the brushes as the old ones were reduced to slivers. Put it back together and assembled to the bike, turned it on and with a bit of praying... pressed the ignition. It turned over at least twice as fast as it used and sounded 10x better! Absolute victory for the night, gas tank is dry and ill be putting some Red Kote in it tomorrow, there is a tad bit of surface rust left after the acid bath in some spots but it says you should be able to put it over some rust and it will seal it.
     
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  14. Minimutly

    Minimutly Well-Known Member

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    Next you should pull the plug on the outside (one or four), set it against the head and crank it over to check for spark. If by some miracle you still have one, do the same on cyl 2 or 3. THEN put the tank back on. If you don't have sparks you should check fuses, power to coils and tci before condemning anything.
     
  15. Dave30

    Dave30 Member

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    Bike is back together and starts strong! No more waiting for the battery to die while starting. I made sure the spark is good as well. Now it's on to tuning! It doesn't seem to idle without choke right now but I only got about 30 minutes to work with it before I had to go to work. I tried vacuum tuning it and I'm unsure if I was lucky or if it simply wasn't set up right but all 4 needles were vibrating in the same direction. I do also have a colortuner that may help me determine if I need to adjust the mixture screws which are out 2 3/4 turns. Adventures for tomorrow!
     
  16. XJ550H

    XJ550H Well-Known Member Premium Member

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    thats a known issue and yamaha makes a fix for it
     
  17. Dave30

    Dave30 Member

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    I was able to figure it out with the assistance of another member. The starter motor was in desperate need of a rebuild and afterwards it worked just fine.
     
  18. XJ550H

    XJ550H Well-Known Member Premium Member

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    if you look at the battery schmatic you will see adaptor bars because the original batterys have a different set up on the battery posts then replacments (reversed)
    so you end up with extensions on batterys to fit them instead of a proper length battery cable to fit directly. just one of the quirks of yamaha. they could have just offered longer cables for when you replaced the battery
     
  19. Dave30

    Dave30 Member

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    Yes the store I got it from was able to give me the same battery but with the terminals swapped. Convenient, although I would have rather gotten the correct terminal setup before I potentially fried my electronics. Its also tight fit but I can still get the covers over it. So a new battery, starter solenoid, coils, wires, plug caps, plugs and rebuilt starter now means the bike starts very quickly which is awesome. It still has the old fuse box which aside from the dust that was on it seems to be working just fine.
     
  20. Dave30

    Dave30 Member

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    Update: So I was able to ride it without any issues for the first time today. It takes a bit to warm up but I can ride it with a bit of choke on until its warm and then it does ok. There still must be some kind of issue as I can get it to idle at 1500-2000 rpm no problem but if it falls below that it will slowly die. Aside from that I pulled the spark plugs and they're all very close to being the same condition which is also great! It pulls strong and no longer backfires on deceleration as well! I ordered new tires to put on, Dunlop 404's as the ones on it are from 2007. Overall extremely happy that its come this far. I cant thank all of you enough for the assistance and will be coming back if there are any more issues. For now I'm just going to deal with its little quirks and enjoy the rides.
     
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