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  4. I have good spark, compression, fuel and air. But no start :(

I have good spark, compression, fuel and air. But no start :(

Scheduled Pinned Locked Moved DTR
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  • S SpookDog

    @kylescave
    I’ve never tried to run an engine on brake cleaner, don’t know if it will. I’ve just used it to test for air leaks...

    Is the plug getting wet when you try and start it with petrol from the carb? Always try choke no throttle at first, then a blip of throttle if it doesn’t fire second kick...

    I’d check the carb if it was me. If it’s clean in the bowl just remove the jets and blow through all the fuel and airways...

    K Offline
    K Offline
    kylescave
    wrote on last edited by
    #4

    @spookdog The only other thing i can think of is the CDI, this model has a 3RM-30 CDI and i cant really find any information about it. I also have a spare 3RM-20 CDI with all the wires cut. if i could re-wire this CDI. Could that work? or at least cancel out the CDI being a fault? ive never had a bike have compression, spark and a clean carb not run before.

    CalumC 1 Reply Last reply
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    • K kylescave

      @spookdog The only other thing i can think of is the CDI, this model has a 3RM-30 CDI and i cant really find any information about it. I also have a spare 3RM-20 CDI with all the wires cut. if i could re-wire this CDI. Could that work? or at least cancel out the CDI being a fault? ive never had a bike have compression, spark and a clean carb not run before.

      CalumC Online
      CalumC Online
      Calum
      wrote on last edited by
      #5

      @kylescave Don't use brake cleaner lol. It will wash the oil off the bore (bore wash) meaning you'll have no start up protection. It's not a wet lube system.

      Yeah I've seen this before many times. Is it "good intermittent" spark? This is quite common when something like the neutral switch, side stand or kill switch is still pulled down. In other words, it will spark a few times but immediately die.

      Always Originate, Never Pirate!

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      • CalumC Calum

        @kylescave Don't use brake cleaner lol. It will wash the oil off the bore (bore wash) meaning you'll have no start up protection. It's not a wet lube system.

        Yeah I've seen this before many times. Is it "good intermittent" spark? This is quite common when something like the neutral switch, side stand or kill switch is still pulled down. In other words, it will spark a few times but immediately die.

        K Offline
        K Offline
        kylescave
        wrote on last edited by
        #6

        @calum Oh yeah i defo would not recommend using brake cleaner, but I'm very desperate to hear it fire up just so i can carry on the build 😂😂. Okay i will check the neutral bulb when i get home, hopefully it is as easy as that.

        This bike has been rebuilt by every nut and bolt. i cannot wait to finally give it a ride. My other full power dt 125 r gets 94mph which i thought was astonishing.

        Fingers crossed this works.

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        • CalumC Calum

          @kylescave Don't use brake cleaner lol. It will wash the oil off the bore (bore wash) meaning you'll have no start up protection. It's not a wet lube system.

          Yeah I've seen this before many times. Is it "good intermittent" spark? This is quite common when something like the neutral switch, side stand or kill switch is still pulled down. In other words, it will spark a few times but immediately die.

          K Offline
          K Offline
          kylescave
          wrote on last edited by
          #7

          @calum Could this be the neutral bulb? or does it have to be a switch to cause this issue?

          CalumC 1 Reply Last reply
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          • K kylescave

            @calum Could this be the neutral bulb? or does it have to be a switch to cause this issue?

            CalumC Online
            CalumC Online
            Calum
            wrote on last edited by
            #8

            @kylescave Won't be the bulb, but neutral switch/kill switch and side stand.

            Usually it's the stand switch. 90% of the time.

            Always Originate, Never Pirate!

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            • CalumC Calum

              @kylescave Won't be the bulb, but neutral switch/kill switch and side stand.

              Usually it's the stand switch. 90% of the time.

              K Offline
              K Offline
              kylescave
              wrote on last edited by
              #9

              @calum i've looped that with a plug so it cant be that i dont think, unless theres break in the wires somewhere in the loom. but i find that unlikely.

              S 1 Reply Last reply
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              • K kylescave

                @calum i've looped that with a plug so it cant be that i dont think, unless theres break in the wires somewhere in the loom. but i find that unlikely.

                S Offline
                S Offline
                SpookDog
                wrote on last edited by
                #10

                @kylescave

                A good intermittent spark! Yep, sidestand circuit sounds guilty

                Other CDIs won’t work. Yes the neutral switch is part of the sidestand kill circuit. The switch is by the gear change lever. The wire often breaks. I don’t know how the sidestand switch is bypassed, so can’t tell if a looped plug is good or not 🙂
                I’d put it back to standard and see...

                I think that there’s a black/yellow ~striped wire going to/from the CDI. I think This is the wire that earths the CDI. Try disconnecting it and checking your spark...

                CalumC 1 Reply Last reply
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                • S SpookDog

                  @kylescave

                  A good intermittent spark! Yep, sidestand circuit sounds guilty

                  Other CDIs won’t work. Yes the neutral switch is part of the sidestand kill circuit. The switch is by the gear change lever. The wire often breaks. I don’t know how the sidestand switch is bypassed, so can’t tell if a looped plug is good or not 🙂
                  I’d put it back to standard and see...

                  I think that there’s a black/yellow ~striped wire going to/from the CDI. I think This is the wire that earths the CDI. Try disconnecting it and checking your spark...

                  CalumC Online
                  CalumC Online
                  Calum
                  wrote on last edited by
                  #11

                  @spookdog " I don’t know how the sidestand switch is bypassed" <- This

                  IIRC it's something odd like that and looping it wasn't sufficient. Used to happen on an old DTR I had. It was the weirdest thing, it would start if you kicked it over whilst simultaneously switching the ignition from the "Off" position to the "On" position.

                  And never start with the ignition off and never start with ignition on. Always the combination of kicking it whilst it was off and switching the igniton whilst it's turning over. Weird fault.

                  Always Originate, Never Pirate!

                  S 1 Reply Last reply
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                  • CalumC Calum

                    @spookdog " I don’t know how the sidestand switch is bypassed" <- This

                    IIRC it's something odd like that and looping it wasn't sufficient. Used to happen on an old DTR I had. It was the weirdest thing, it would start if you kicked it over whilst simultaneously switching the ignition from the "Off" position to the "On" position.

                    And never start with the ignition off and never start with ignition on. Always the combination of kicking it whilst it was off and switching the igniton whilst it's turning over. Weird fault.

                    S Offline
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                    SpookDog
                    wrote on last edited by
                    #12

                    @calum
                    Sounds like an under seat solenoid dilemma!

                    @kylescave
                    Actually 3rm 20 & 30 might be changeable, I was thinking of the earlier 3nc unit which is ‘standalone’ IIRC
                    What year is your bike? After 1997? I don’t think your problem is the CDI unit though. It does sound like a side stand or other ignition earthing problem ...

                    Check the neutral switch!...

                    K 1 Reply Last reply
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                    • S SpookDog

                      @calum
                      Sounds like an under seat solenoid dilemma!

                      @kylescave
                      Actually 3rm 20 & 30 might be changeable, I was thinking of the earlier 3nc unit which is ‘standalone’ IIRC
                      What year is your bike? After 1997? I don’t think your problem is the CDI unit though. It does sound like a side stand or other ignition earthing problem ...

                      Check the neutral switch!...

                      K Offline
                      K Offline
                      kylescave
                      wrote on last edited by kylescave
                      #13

                      @spookdog @Calum Found it!, i found a break in the kill switch wire in the middle of the loom! Not sure how it was broken but it was obviously breaking the circuit. As soon as i sorted that it fired straight up. Many thanks for all the ideas and help. very useful.

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