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Yamaha Zeal Sudden Throttle cutout

Discussion in 'Technical and Troubleshooting Torque' started by ropesalad, Oct 24, 2015.

  1. Hoping I can find some help with this one... any suggestions greatly appreciated

    Ive had the bike about three weeks and has all been fine so far. had just pulled onto a main road and was in the 8-9k rev range accelerating. changed from 3rd to 4th gear and suddenly the throttle just cut. tried winding the throttle and the spring tension on the throttle was still there but no response at all. coasted to the side of the road cycling through the gears to slow me down.

    I couldn't get the bike up the curb as there was a steep grass bank and nowhere to pull fully off the road. Got passed by a truck a little too close for comfort so i had to wait until the road was clear and push it all the way across to the other side into a carpark of an office building.

    I was a bit shaken up by the whole thing but after regaining my composure i gave the bike a once over and all seemed fine. started it (fine), let it idle for a while, revved the bejeesus out of it to make sure i still had the full rev range without any cutouts and rode around in gear in the carpark. all fine, rode home with no issues.

    A couple of days later in very similar circumstances accelerating in mid range revs the throttle responsiveness totally disappeared again. Shifted down a gear and let the clutch out slow and the throttle response came back.

    i didnt think it sounded like a fuel problem because of the suddenness of the cutout. I sat and had a good think about it and decided i might have pressed the killswitch by accident but when it happened a second time it was the first thing i checked and it wasnt on.

    Any ideas would be greatly appreciated :)
  2. Sounds like an electrical gremlin, Start by checking all wiring and connectors up to and around the coils.
  3. I would check all related wires and connections too. Start from your spark plug and cap and the lead.
  4. Side stand cut out switch, clutch switch or wiring to them ?
  5. Just had a bit of a fart around with all the connectors.... I have my suspicions about the killswitch on the bars so just traced the wire back to the connector under the headlight and reseated it. started the bike to make sure all was OK and the front indicator didnt work anymore :( tested the bulb with the multimeter and that was fine. reseated it and indicator was working again....... :arghh::arghh::arghh: Hopefully reseating the connector might have helped, couldnt see any corrosion. Want to use up the fuel in the tank before I go through all the drama of getting it off to do any more serious investigation. Thanks for all the suggestions so far
    • Like Like x 1
  6. At the risk of starting something like the oil controversy thread, contacts can be protected by the use of non-conducting dielectric grease. This is a grease or gel which is not conductive itself, and does not mix with water and prevents corrosion by preventing coated surfaces from ever coming in contact with water.

    The theory is that clean connectors will displace the grease and make metal to metal contact when seated. It comes a bit unstuck when connectors are already slightly oxidised and the connection is not good ahead of applying grease to the connector. Clean connectors are an essential for this to be of much benefit. In practice, some mechanics just use automotive grease on things like trailer plugs

    Now the disclaimer - dielectric grease is often used in new installations of irrigation fittings like the wiring of solenoid valves where there will likely be some exposure to moisture to the connections. However, in low voltage circuits (e.g. 6 or 12 volt) ANY barrier to electrical conduction is not a good thing and there are those who believe, possibly rightly so, that the only benefit of the grease is to prevent corrosion and it may actually hamper current flow if the connection isn't really tight and very clean to begin with on those low voltage circuits. The fact that many better irrigation part suppliers provide this grease for their connectors says something of its usefulness.

    Now the problem for motorcyclists is that the socket and pin connectors are often not well sealed, often only enclosed in a plastic sleeve or fitting and every time you wash your bike or ride in the rain, there is some exposure to moisture and they are not exactly gold plated, are they, so corrode slightly, decreasing the metal to metal contact in the connection to the point where the connection is lost.

    The hard part is cleaning the connectors. My best success has been with a sheet of very fine emery paper (maybe 1600) to clean up contacts. it can be cut up into pieces and rolled into a tiny tube, to do the female side of pin and socket connectors, or glued to an icy pole stick and used to scrape blade type male connectors - though the socket side (often embedded in a plastic fitting is harder) After scraping oxidised surfaces, they are often more susceptible than ever to the effects of moisture as you've removed some of the protective layer (if they are plated fittings), and the grease is useful there. This has worked for me where I've found the offending connector, usually discoloured from oxidation, whitish on silver coloured metal, or dark or greenish on copper coloured ones.

    For what it's worth. This may or may not be useful.

    IF your problem is one of connectors, this may be of use, but I realise your problem may have a different origin. Good luck with it.
    • Informative Informative x 1