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misfire on a V75

Discussion in 'Small Block' started by redwitch, Aug 18, 2018.

  1. redwitch

    redwitch Tuned and Synch'ed

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    Hi everybody.

    My V75 is on the road after 2 years of rebuild. A nice bike, very torquey and fun. The engine runs well, but keeps giving a few misfirings on the left cylinder. when reving low, and accelarating again, it bangs a couple of times. sometimes also going downhill. plugs and HT wires are new, i suspect a faulty coil. anybody with an idea? thank you and good rides to all. HG
     
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    You may be correct. Swap coils side to side and if the fault appears on the right cylinder you have your fault isolated.
     
    Trout likes this.
  3. redwitch

    redwitch Tuned and Synch'ed

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    hi, good advice, , I'm going to try it and have a go. thanks a lot. any way of measuring the coil to see what is wrong? i do not have many infos on the electrics of this bike. ( not very electric specialist either…) I guess there is a resistance level that shows if the coil is OK, but I don't have the data. would you suspect the " black box " of the electronic ignition on that type of problem? regards. Hervé.
     
  4. V700Steve

    V700Steve High Miler GT di Razza Pura

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    What year V75?
     
  5. redwitch

    redwitch Tuned and Synch'ed

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    Hi. it is a 1987 italian made, of course, but sold in France, with the 2 valve heads. it used to be dressed with a big road fairing, as used by the police. All is gone now, i made it a pure roadster, 16 pounds lighter. all is OK, except these backfires… H
     
  6. V700Steve

    V700Steve High Miler GT di Razza Pura

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    The ignition could be at fault also, in the States here we were getting points in the smallblocks.
    Found a manual, looks like you have a Motoplat or Digiplex. Wouldn't hurt to shine a timing light in the hole on RH side to flywheel.
     
    Last edited: Aug 18, 2018
  7. redwitch

    redwitch Tuned and Synch'ed

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    I steve. I see that you sent the message at 4.22AM. Did you have an inspiration , coming back from a disco? anyway, thanks for it.
    my bike has an electronic ignition. I checked it and tried some very slight moves to see if it would make difference. nothing evident, it is back to normal setting. I wonder if it is possible to detect a fault in the HT coils with a resistance meter ( I dunno the exact name in english) but, first I am going to swap the coils to see if it makes a difference.
    have a good sunday. riding?
     
  8. V700Steve

    V700Steve High Miler GT di Razza Pura

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    Yes, inspired! Worked on the stuff w/it was new. We didn't get V75's much only V65's then V75 w/FI in around 05.
    Hey, I hate disco!!! I was more of an Acid Rock listener. Do a search on checking coils, it's basic but you need a meter.
    Yea, it's around 8hrs difference to EU I guess.
     
  9. redwitch

    redwitch Tuned and Synch'ed

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    hi again. we did not get manyV 75 either in europe. the V6( was the most common. They made the bigger to try to cope with the new japanese of the time, but it was a bit useless, the kawasaki ninja was 70 mph faster for nearly the same price… But the V75 prepared the V7's of today, , very similar engine. regards. Hervé.
     

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