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Can you diagnose the issue based on these spark plugs?

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    Can you diagnose the issue based on these spark plugs?

    I am a rookie at carb tuning. See if any of you guys can steer me in the right direction. I rebuilt the carbs ( among other things ) on a bike that has been out of operation for many years. It is running, but not well. I pulled the plugs and...

    back plugs


    front plugs


    hmmmmm.... something is whacked. Here are some points on what I have done, let me know what you guys think. I appreciate any tips.

    - top end has just been rebuilt too
    - stock everything ( jets, slider springs, airbox, exhaust )
    - I believe I did a fairly good job cleaning the carbs, torn them down did the spray down and soaked in carb cleaner for a day or so. There was a lot of varnished gas in them. I *think* I hit everything.
    - carbs were initially set to the manual spec for an 88 2 1/8 out, but have been run some as "in" as 1 1/2. Mostly around 2 I would say.
    - It has probably run a total of about 15 mins only on center stand. Max rpm maybe 3500, but most running was around 2000.
    - mostly smokes light grey when running
    - at one point I had one of the back plug wires disconnected accidentally and it was arching to the frame.

    #2
    man... those are some clean back plugs... sure there's any spark at all from them? pull a back plug, attach it to the wire, and ground it... see if there's any spark at all. Might have fried something when it was arching out.

    Bill

    Comment


      #3
      I was thinking the same thing. No combustion happening in the rear.
      BIKES: Honda: RC31 Racebike/ NT650 Streetbike, DUCATI: None at the moment.
      Former MSF Rider Coach / Trackday Instructor/ Expert Roadracer #116
      "I'd rather ride a slow bike fast than a fast bike slow."

      Comment


        #4
        Rear coil? Looks like your not getting any thing there double check running backwards from the plugs.
        1\2 Liter Duc Eater

        Comment


          #5
          Thanks guys. Well I went out and tried to test the spark. I got nothing at EITHER cylinder . May not have tested it right. Here is what I did ... pulled the tank and ran it a little on the starter to hopefully clear most of the gas, drained the float bowls too. Started with the front cylinder, pulled the "easy" plug and bungie-ed it to the cylinder. Ran the starter and nothing, checked the kill switch it was ok, nothing. put the plug back in and tried the back grounded on the subframe nothing.

          Let me know if you guys do anything different to test. More info the better .

          Next I am going to try and run though the ignition troubleshooting section of the manual.

          Comment


            #6
            You could try a search on the hawkgt.com archives. Go to hawkgt.com > mailing lists > search archives. The list has been around a long time so maybe someone else has had the same issue.
            '89 Hawk GT

            Comment


              #7
              You did remove a single spark plug from the c-head and then put it back in the plug cap?
              '95 ShaftHawk 650P>
              Front: Bros Mk2 front wheel; Mk1 forks; MetalGear disc; NC30 caliper; cb1 yoke.
              Breathing: Hacked up and shortened ART tri-can on collector and link pipe from DemonTweeks.
              Other: RGV bars; DefT dash; modded subframe; modded rearsets; relocated ignition.

              '91 Bros 650 Mk1>
              Currently off the road.

              Comment


                #8
                Originally Posted by DefTrap
                You did remove a single spark plug from the c-head and then put it back in the plug cap?
                I did, but you are not wrong to double check me

                Comment


                  #9
                  Well you never know ...

                  You must be getting some spark or it wouldn't run at all. Something doesn't add up. It is still running?
                  '95 ShaftHawk 650P>
                  Front: Bros Mk2 front wheel; Mk1 forks; MetalGear disc; NC30 caliper; cb1 yoke.
                  Breathing: Hacked up and shortened ART tri-can on collector and link pipe from DemonTweeks.
                  Other: RGV bars; DefT dash; modded subframe; modded rearsets; relocated ignition.

                  '91 Bros 650 Mk1>
                  Currently off the road.

                  Comment


                    #10
                    Sounds like the plugs aren't getting a good ground during the test... Grab some wire, and wrap it around the metal part of the plug, attach to the - pole on the battery. That way you're sure it's grounded.

                    You've mentioned the kill switch... you're grabbing the clutch too?

                    Bill

                    Comment


                      #11
                      It ran yesterday rough, so it was getting at least some spark then. Yesterday at some point I accidentally had one of the back spark wires disconnected and it was arching to the frame while it was running from the wire ( the plug was in ). So yeah I am little confused too. I will try bill's suggestion. One more thing ... how many amps are running through these pups? How concerned should I be with lighting myself up?

                      Comment


                        #12
                        There's no need to touch the plugs during the test... you only want to see a spark or two...just be careful. I would definitely resist the urge to lick one!

                        Bill

                        Comment


                          #13
                          cool. Wanted to make sure I wasn't being overly cautious.

                          earlier my brother recommended standing in the kiddie pool and holding the plug with my teeth, but I resisted.

                          Comment


                            #14
                            If you get no fire at all as you test it farther check your fuses. You may have a blown one. Just a thought.
                            '88 Hawk GT
                            '89 Harley FXSTC
                            2008 Yamaha V-Star 1300 tourer

                            http://www.hawkgtforum.com/viewtopic.php?t=948

                            "...my performance ain't perfect, but its loud, and its fast..." -Widespread Panic

                            Comment


                              #15
                              ok. So I am an idiot. painted surfaces are not good grounds . I grounded to the frame and both front and back are getting spark. I also ran through the ignition troubleshooting section and the coils, fuel pump relay and CDI ( or at least the wiring to it ) all check out to spec in the manual. On a goose chase I freaked out thinking maybe I had little to no compression in the rear cylinder, but bought a compression tester and all is well. Sweet I did remember to put the rings in.

                              So I am guessing one of two things...

                              #1 the back cylinder is getting no gas. The bowl had gas in it so I it gets that far, but maybe I missed something during cleaning? and the slow jet ( or all jets ) are clogged? or maybe the float is stuck?

                              #2 The front choke plunger (or cable) is sticking open causing the front to burn real rich. Since the motor has only run 10-15 mins in total via 1 to 2 min spurts, could the back plugs be this clean? The front choke plunger does have some discoloration on it and the choke cables definitely need to be replaced.

                              What do you guys think?

                              Comment

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