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I did a thing... a CB900F thing

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Thread: I did a thing... a CB900F thing

  1. #31
    Ews
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    Geeto, your the man
    Dream as if you live forever, Live as if you die today.~ James Dean

    I feel the need, the need for speed.~ Mavrick (Tom Cruise before he was a big ol' bag of crazy)

  2. #32
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by Ews View Post
    Geeto, your the man
    Shhhhh!!!! you'll ruin my "salty" reputation.
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    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.
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  3. #33
    Senior Member TrialsRider's Avatar
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    Quote Originally Posted by Geeto67 View Post
    Shhhhh!!!! you'll ruin my "salty" reputation.
    Captain?
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  5. #34
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by TrialsRider View Post
    Captain?
    more like Tennille
    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.
    - Samuel Beckett
    A tool is just an opportunity with a handle
    - Kevin Kelly

  6. #35
    Ews
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    Saturday evening I noticed a small random backfire(not sure it could actually be considered a backfire, maybe more of a slight pop). My first thought is that I have a plug fouling out, but I have not had time to pull my plugs and check them, will likely just replace them anyway so I know when the most recent time was. But I got to thinking about it this morning, and I have come to two possible causes.

    1. I filled the tank at a new gas station on Friday, always use premium non-ethanol, just found a station close to my work that has it. So possibly bad gas?

    2. After doing some reading in other CB900 specific groups/forums I found that people run their idle at 1100-1200 rpm. Mine was set at about 800-900 from when I bought it. So I turned the idle up to about 1100 and went on about my business, that was Thursday. Normally I would not even consider this as a possible cause, but this bike has been Jetted with DynoJet. So I wonder if that could be why the idle was turned down? I turned the idle back down when i got to work this morning, so we will see.

    On a side note, I racked my brain all weekend trying to figure out the cause and it was my short ride to work this morning that made those ideas pop into my head. Just proof that a ride makes one think more clearly!
    Dream as if you live forever, Live as if you die today.~ James Dean

    I feel the need, the need for speed.~ Mavrick (Tom Cruise before he was a big ol' bag of crazy)

  7. #36
    Senior Member Geeto67's Avatar
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    The factory manual setting for the 900F idle is 8-900. People turn the idle up on the 900F (and most 1969-1983 large honda aircooled fours) because the bikes are "cold natured" and usually won't idle at all until warmed up if the ambient temp is below 60 degrees F. I have known guys who have installed remote idle adjustments on their bikes so they can turn the idle up on when cold and then turn it down when the bike is warmed up (and not just on hondas - I have one on my ironhead and dad has one on his fatboy).

    Backfiring through the pipe is a sign that you are not getting a complete burn in the cylinder. Usually when you see these on DOHC it's a sign that something electrical in the ignition is about to go. The common fail points are the coils, pulse controllers, Reg/Rect, and stator. Bad wires can also cause this - esp if one has burned through.

    - Coils: those will be easy to detect, just take them off and inspect them, look for cracks. Also warm the bike up and then take the tank off and run the thing in the dark, looking to see if the coil is arc-ing. Resistance at the coils should be around 3k ohms. If it is 5K ohms it's probably no good.

    - Wires and caps. I believe the resistance in the stock plug wire cap should be between 5K ohms and 9K ohms. If they are beyond that then consider them burned out and replace them. Also check the resistance across the wire which is somewhere between 10K and 12K ohms per foot, anything over and replace them.

    - Pulse controllers - eh I think there is a procedure in the manual for checking these.

    - Regulator/Rectifier:

    Don't forget to check your charging at the battery as well. Honestly though, if it was just a one off, wait and see if it happens again.

    final thing about DynoJet kits - they are about 50% marketing, 30% improvement, and 20% bullshit. At one point dynojet put a stock bike on the dyno and re-jetted until they saw gains and then put that package together and sold it. They are not a replacement for actually dyno tuning your bike - It's just a jet kit to fix the emissions lean fuel settings from the factory. Do they work? sometimes, but if you are really after max performance you should just dyno tune the bike...after you install kehin CR's and a bassani pipe.
    Ews likes this.
    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.
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  8. #37
    Senior Member Cyorg's Avatar
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    When you are chasing down popping in the exhaust, don't forget the air cut valves. There to control popping on decel, but still shouldn't be excluded from the troubleshooting tree... could be leaking.
    "Non urinat in ventum"

  9. #38
    Ews
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    Turned idle back down to 800-900. Seems to be ok now but I will keep my ears open for it again.
    Dream as if you live forever, Live as if you die today.~ James Dean

    I feel the need, the need for speed.~ Mavrick (Tom Cruise before he was a big ol' bag of crazy)

  10. #39
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by Ews View Post
    Turned idle back down to 800-900. Seems to be ok now but I will keep my ears open for it again.
    FYI - Idle should always be set hot not cold. don't know if you know that but if you set it 800-900 hot, it may not run cold off choke (or at all). If you set it 800-900 cold, it may idle at 1000-1200 when warmed up.
    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.
    - Samuel Beckett
    A tool is just an opportunity with a handle
    - Kevin Kelly

  11. #40
    Ews
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    Quote Originally Posted by Geeto67 View Post
    FYI - Idle should always be set hot not cold. don't know if you know that but if you set it 800-900 hot, it may not run cold off choke (or at all). If you set it 800-900 cold, it may idle at 1000-1200 when warmed up.
    Yea, I always adjust idle when hot. I haven't had much cold blood issues, beyond what I would expect from a 36 year old bike. But then its over 60 when I wake up every morning.
    Dream as if you live forever, Live as if you die today.~ James Dean

    I feel the need, the need for speed.~ Mavrick (Tom Cruise before he was a big ol' bag of crazy)

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