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frustrated at 78 gs550

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    frustrated at 78 gs550

    I have a 1978 gs550e in great shape. 14,000 miles. ran great last year before i put it away for winter. went thru the carbs this week, cleaned em and reset floats, synched etc and they are perfect. I have a mjor issue with cold starting (not even when its just cold outside, it could be 65 degrees and if its the 1st time you are trying to start it). im pretty sure its a misfire in the ign system. I did repl points and set the gaps to .014", new plugs, same issues. the condensers were replaced last july. It seems to be only firing or attempting to fire on 2 cyls on intial start up, but if i do get her running, she runs perfect all day long. Im thinking of repl a coil ( i have spares already from a donor bike) ( im pretty sure its no 1 and 4 acting up) or repl condensers again ( ileft it out several days during winter with out the cover, maybe mositure got to them already??) Its def arcing (sparking) across the number 1 and 4 points when they are open, and i dont think thats a good sign for the condenser being perfect. any one think of anything else im overlooking before i do the condensers and coil replacement??

    Thanks for the help.
    Vinny

    #2
    I would fix the arcing problem at the point before you replace the coil, it sounds like you already know your problem. Once you get the condensor and point sorted out, hook up a timing light to #1 or #4 and check out how the spark is. Repeat this procedure after the bike is really hot and idleing (max heat build up in the coil).

    ~Adam

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      #3
      Are you sure the correct spark plug wires are on the right plug? Happened to me once. Set the gap carefully and then check the timing. If you move the plate to set the timing, check the gap again. points are a pain in the ass as you already know. I would move to electronic if the budget allows
      1981 GS650G , all the bike you need
      1980 GS1000G Power corrupts, and absolute power corrupts absolutely

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        #4
        I found that my bike ran better with the plug gaps set to minimum. My points were a constant source of frustration, and my timing was constantly ending up to far advanced. I'm upgrading to a Dyna S and some Katana coils to bring my bike into 80's technology.

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          #5
          i was wrong, fixed the arcing on the pts with new condensers, swapped out both coils from my donor bike and gives the same starting issues. actually brought home some good spark testers from my shop and i have plenty of spark at all 4 cyls, but it only was attempting to fire on #2 (exh pipe was warm while the rest of the cyls were ice cold.) Compression is good on all cyls (155#), timing is fine, intake boots/o-rings were new last april (stil in good shape), getting fuel to carbs (petcock is fine) it looks like its back in the carbs again, which will be about the fourth time in them, and they always look clean, etc. The wierdest thing is i cant tell if im lean or rich. plugs are never wet looking like they are flooding, but yet if i spray starting fluid into the carbs it doesnt start either. IM starting to get mad at this thing and my fiancee is even noticing my anger, hahaha.

          any ideas or suggestions if i am overlooking something in the carbs, i went thru them thourougly. cleaned all jets, passages, needles and seats are a year old and still look new ( i only rode bike 150 miles last year), cleaned choke passages, plungers, etc. floats look fine and set at 1.0" about 25.4-26mm per haynes manual. i have emgo pods on it and have the 95 mains, stk pilots, pilot needle at 2 turns out and air screws at 2 turns out, needles are raised 2 washers. she ran fine with this set up last year.

          thanks for any advice, im kinda lost at this point and the weather is getting nice, ive get the urge to ride and i want this thing right.

          Vinny

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            #6
            Your jetting sounds right. What are the fuel pilot screws and air screws set to?

            To rule out that you fouled the spark plugs (you said you had spark with a plug tester?) I would put new spark plugs in and see what happens.

            ~Adam

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              #7
              Well it running 100% now, finally, thank the lord. :-)

              Im a small engine technician/service manager and I do carbs all day long, even race mikuni carbs on my racing karts and made a stupid oversight. I cleaned the choke pick up tubes on the carb bodies, but forgot to clean the little hole in the bottom of the bowl for there chambers. They were all plugged solid with sediment,etc except the one cylinder that was firing. cleaned the chambers out put the carbs back on last night, just doubled checked my point gap, new plugs an she kicked off so easy, better than it ever did since i got it last march. It actually runs rich on full choke now, were i ahve to take it down to half choke pretty quickly, cyls heated up with in minutes. Im so thrilled with the way she starts now.

              I checked my ign timing, 1,4 seem to be hitting dead on the f1-4 mark at idle and are advancing properly. but i am getting some spit back from the carb throats when i go to accel them. not bad, bikes runs great but you can see it, were you cant see any spit back from carbs 2 and 3. all the carbs are tuned the same, there not flooding, so i think its ign timing related. when i checked 2and 3 they are actually hitting just a little after passing the f2-3 mark (like maybe a 1/8"-3/16" after). That would mean that 2/3 are firing a little more advanced right? I know thats better for top end rpms, but is it helping get more air/fuel charge into 2/3 at 1200-2500 before ign, and 1/4 are firing a little sooner and spitting out what it cant handle before ign. should I mess with the 1/4 timing, or is this little spit back normal???? I also though it could be int valve timing/lash, but to be on 1/4, i kinda leaned away from that idea, as they are tied together by the ign system.

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