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  • #91
    25dc trouble shooting

    Thanks John for the info.

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    • #92
      25 DC Running Problems

      Hi Folks,
      well my 25 Dc Sporstwin is now re-assembled, but like many other 25 DB/DC projects before mine, I can't get it to run smoothly on both cylinders. It starts ok and ticks over but as soon as I pull away and get up to 15 mph plus, it starts missing on the RHS cylinder. I've replaced the condensers (both) and fitted a new plug on RHS, but problem persists.

      I am now looking to replace, initially, the ignition coil for the RH cylinder. I see that Villiers Services are offering coils for 4T bikes. These seem to look very similar to 6 volt coils for certain early Honda small capacity machines that I've seen on the internet, at a lower price!. Can any one out there suggest a suitable replacement 6 volt coil for my Sporstwin, please? The Villiers specialist at VMCC recommends either a Jap coil or a Bosch.

      Graham of Greasby
      Attached Files

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      • #93
        The small jap ones are ok, loads on eBay, just pick one at the lowest price, cheaper than VS & other 'classic' suppliers.
        I notice you do not have an air filter fitted in the pics, this might be part of the problem, ie its running weak.
        Last edited by John Wakefield; 16/12/2012, 06:36 PM. Reason: Air filter ref added

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        • #94
          25 DC Running problems

          Hi John,

          Re; the missing air filter in the pic. I don't think it is the problem (weak mixture). I actually took it off to check that the slide in the carb. was seating all the way down after replacing the throttle cable and new twist grip. Had to do some fine finishing on the twist grip internals to ensure the carb. slide was bottoming. (BTW,I found that the paint finish on the 'new' air cleaner canister was not petrol resistant!)
          The Villiers coils have two connections for the low tension wires but some of the coils advertised on the internet seem only to have one L.T. connection. Where does the other L.T wire connect to on the replacement coil, to the body of the coil? Also, how do you test the polarity of the L.T. connections on the harness; on my loom, the L.T. wires are the same colour - blue for front(RH) coil, green for rear (LH) coil ?
          Thanks! G of G. Merry Christmas all you 2T and Roadster riders!

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          • #95
            25dc trouble shooting

            Hope you are soon out of the woods Graham,meanwhile look what I picked up for my Xmas pressie this year !
            Attached Files

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            • #96
              Originally posted by Graham of Greasby View Post
              Hi John,

              Re; the missing air filter in the pic. I don't think it is the problem (weak mixture). I actually took it off to check that the slide in the carb. was seating all the way down after replacing the throttle cable and new twist grip. Had to do some fine finishing on the twist grip internals to ensure the carb. slide was bottoming. (BTW,I found that the paint finish on the 'new' air cleaner canister was not petrol resistant!)
              The Villiers coils have two connections for the low tension wires but some of the coils advertised on the internet seem only to have one L.T. connection. Where does the other L.T wire connect to on the replacement coil, to the body of the coil? Also, how do you test the polarity of the L.T. connections on the harness; on my loom, the L.T. wires are the same colour - blue for front(RH) coil, green for rear (LH) coil ?
              Thanks! G of G. Merry Christmas all you 2T and Roadster riders!
              One terminal on each Villiers coil goes to earth, the positives are as you say blue & green wires from loom. The single contact coils will be internally earthed so will not need seperate earth connections. Just connect the blue & green wires to the single connections on new coils.

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              • #97
                25 Dc Running Problems

                Hi John, Bryan and any body else watching!

                Thanks for clarifyling the 'terminal/polarity' query, JW! I don't need to experiment with an AVO meter now!

                Bryan, what was the 'pressie', the Sporstwin or the passenger?

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                • #98
                  25dc trouble shooting

                  I'll give you just one guess Graham [a] Greevsie or [b] Kylie !!!!!

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                  • #99
                    25 DC Running Problems

                    Happy New Year to all the GRA readers, linkers, moderators etc.!
                    I've now fitted a modern (Taiwanese?) 6 volt coil which are described as replacements for the coils on Honda C90 Zs. The maker's name is Wat Yong. I paid 19 locally from a m/cycle sales and repair shop. On the 25 DC, you will just need to make up a fairly simple bracket to suspend the new coil from the coil holder/hanger under the top tube. This new coils seems to have resolved the ignition and running problems, I'm pleased to report! As this coil appears to generate a bigger, brighter spark than the original Villiers coil that's still firing the LHS cylinder/plug, I've ordered another C90 Z coil. So another bracket is required!
                    Another idea for what it's worth; I picked up a lawn mower petrol tank plus tap from a local mower repairers to use as a temporary petrol tank whilst I've been trying to deal with my recent running problems. I don't know about other Greeves bikes but it's a real p.i.t.a. removing/refitting the tank every time you need to get at the coils and wiring connections. It's off an Atco mower, is plastic and holds about 2.25 litres or 1/2 gallon. Just use a couple of cable ties and some pipe insulating foam round the top tube to keep it secure.
                    Thanks J.W. for the pointers and advice!

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                    • 25 DC Trouble Shooting

                      Hi Folks,
                      I recently discovered that the two crankcase drain plugs were only finger tight and after draining any surplus petroil from the engine, tightened them up properly.
                      Amazing the difference this made to running; making the clutch slip now!
                      Wished I'd checked them a lot earlier! We live and learn, I suppose!
                      Thought it might be worth mentioning for the benefit of others rebuilding a bike with a 'working engine'.

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