Engine Troubles

Discussion in 'Mechanics Garage' started by Expvet, Jul 18, 2018.

  1. Expvet

    Expvet New Member

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    I have a 2006 VFR with 8,800 miles on it. Today while riding home stopped at a light the engine began to run rough and the idle dropped below 1000 rpm. It stayed on but was low on power. I rode it home and could rev up to 4000 rpm but it felt like it was misfiring. There was no backfire. When I got home and put the bike on the side stand the idle suddenly smoothed out and I could rev it without issues but once I got on and straightened it out off the stand in a few seconds the bad idle from earlier began. This repeats consistently. I noticed that from one exhaust muffler (I have Leo Vince) the exhaust is cooler than the other but cannot say if this is different than usual since I have never compared the two before. Last year near the end of the summer the bike suddenly would not turn over. This was remedied with new plugs but it has only been about 1,000 miles or less that I have put on these plugs. Any ideas?
     
  2. Diving Pete

    Diving Pete Insider

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    With a cold engine - start it.
    Quickly spray the down pipes on each cylinder with a hand pump container - DO NOT USE YOUR HAND !
    This will then become obvious which cylinder is misfiring - the others will burn the water off as steam rapidly.
    Check that plug / lead.
     
  3. Expvet

    Expvet New Member

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    Spray with water, starter fluid or gasoline?
     
  4. Allyance

    Allyance Insider

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    Water!!!!
     
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  5. squirrelman

    squirrelman Member

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    engine must idle for at least a minute to evaporate the water you spray.

    no FI codes ?????????
     
  6. RllwJoe

    RllwJoe Member

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    You have a 12 year old bike, no? 8800 miles? That is just over 730 miles per year! 4 tanks of gas per year.

    Have you taken a look inside your gas tank? It may have rust plugging up the fuel system.
     
  7. Diving Pete

    Diving Pete Insider

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    Having reread my post it's not that obvious that I did say water. It is in there....
    The reason to use water is it will not catch the bike alight when the down pipes get hot.
    Water will just boil off as steam. The Down pipes get really hot very quickly and are linked to each cylinder. This helps tell us which cylinder isn't firing correctly as it will take longer to get hot.
     
  8. pandes

    pandes New Member

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    That’s interesting![​IMG]
     
  9. Expvet

    Expvet New Member

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    It has been a while but this Northeast summer was one of the rainiest bad riding ones I can remember. As stated earlier the misfiring was something that would mysteriously disappear when I would put the bike on the sidestand and resume when upright. I was going to disengage the sidestand and test the fuel regulator but while doing some on and off the sidestand observation I began to notice that what was affecting the the good idle/misfiring was really when my weight (185 lbs.) was on and off the seat. When I started to look at it from that angle I observed that my Power Commander, which is in a small slot right behind the rear brake fluid reservoir, was directly under a tab on the underside of my Sargent seat. I noticed a slight depression on the Commander's case right where the tab sat. I relocated the PC in the slot so the tab totally clears it and that seems to have resolved the issue. It seems as if the slow building of the depression eventually must have resulted in pressure on a circuit board component that either cut or interfered with a signal that messed with the mix. The bike even runs a bit smoother in the lower revs. It possibly may have been showing some gradual performance degradation signs as the depression was building that were too subtle to notice at first but eventually led to the misfiring issue. It has been flawless the last three days of commuting ,so I think this may have solved the problem. What a nightmare, had I not found this and went through the sidestand and pressure regulator checks without results it would have gone to a shop, which may or may not have found the real cause of the problem but definitely would have been a couple of hundred bucks. Thanks to all for pointing me through the process of elimination, it helped isolate the cause. Now to enjoy some fall riding before the weather turns into winter storage time.
     
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  10. Diving Pete

    Diving Pete Insider

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    At least it's now figured out... well done.
     
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