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HT Lead failure: two questions

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by mattb, Dec 13, 2010.

  1. G’day All.

    I’m trying to trouble-shoot whether possibly one of the HT leas or coils is at fault on the Hornet. I have two questions:

    1. If there’s a short from my HT Lead to the engine, will wrapping the lead in electrical tape be enough to temporarily right it? (So as to reveal whether that’s the problem)

    2. Could such a fault be something that occurs only when the engine is hot?

    (Background: when bike heats up the idle starts to waver, then gets so bad that the bike stalls when I stop at the lights. This is at low rpm – it usually runs fine higher rpm, though sometimes (rarely) drops to three cylinders. Given that spark plug number three has needed replacing twice this year due to the cylinder not running, I’m suspecting HT Lead short to the engine, or more likely that the coil is failing when it heats up. It’s cheaper to start with the lead. Now, I don’t know if it’s related, but the bike manifests exactly the same symptoms when it gets soaked with heavy rain. I recently sprayed some WD-40 in at the leads and it came right for moment in response. Maybe both a lead and coil are at fault...)

  2. yes and yes
  3. +1 yes and yest..run the bike in the dark,cover the head and tail light if you need to. Get down close and look for a little lightning storm along where the lead rests.
    Even if you cant see a split there may be a weak spot in the insulation that will allow amps to leak out. If you cant see sparkage try the electrical tape and see if it makes a difference anyway. I dont know if sticking your tongue on the bike would pick up any stray current..but licking your bike is an acceptable way of showing affection.
  4. Try the leccy tape, should work.

    New leads (I'd do all of them) are a good thing to do if the tape doesn't work.

    If all that fails I'd use it as an excuse to get an aftermarket high-output coil pack.

    Cheers - boingk
  5. Does it run two coils?

    The manual should tell you how to test the coil and leads. also, if it runs caps, they can cause symptoms like this.

    Spraying some water around whilst the motor is running may show up a cracked lead.

    These symptoms also come about with old vacuum hoses to the fuel tap. Just replace it.
  6. Another possibility is the hall effect ignition pickups. They can be fine when cold but start playing up when hot.

    If it is the pickups and Honda try to shaft you for replacements, don't despair. Generic hall sensors are about 10% the price of identical factory ones. They were for my K100 anyway. With any luck, Honda would also use something you can find a substitute for by trawling the Internet electronics catalogues, as I did.
  7. Change all the leads if they're more than 5 yrs old, then start trouble shooting from there. My gf's car started running on three recently, changed leads, all fixed. 15 yr old car.
    +1 on having a look at the leads in the dark if youy really can't afford to change them on spec.
  8. Can you seperate the leads from the coils? If so, swap with a known good one. You should be able to work out where the fault is.
    Are you sure it's not fueling? Is your bike using any oil?? If the valve seal is perished it will cause similar behaviour.
  9. Bike was doing it's usual bad running the other night. I pulled over in a dark street, had a look, and sure enough: a nice little electrical storm was to be seen! So first thing's first, replacement leads!
  10. It's nice when a problem makes itself so visually obvious :D.
  11. If you can get your tongue in close enough you could confirm the diagnosis before blowing money on leads....................
  12. My old man used to tell of how, in wet weather, the magneto and HT lead on his ancient BSA 250 used to leak so much that his party trick was inducing a six inch spark between the side of the tank and his right knee :LOL:.
  13. Your Dad had a a British magneto that produced a spark? Unheard of!
  14. They're not that feeble. I've had a few good belts when playing with them on autojumble stalls. Much to the amusement of the stallholders, who were a bit sick of pokers and fiddlers, I might add :D.

    Trouble is, they're precision bits of kit that don't take kindly to being left out in the weather for 30 years, then "rebuilt" by a monkey with a hammer and a pair of pliers.