knocking

Discussion in 'Softail Models' started by saintNH, Apr 21, 2011.

  1. saintNH

    saintNH Member

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    I just took my 01 fatboy out for the first time this year. I rode it twice this week and I am noticing a knock on acceleration ONLY which sounds like its coming from the front of the motor. it only happens if I roll onto the throttle anything more than gently. Over the winter I did repaint the bike, so I took the tank and fenders off, but I lock-tited every bolt when I put it back together, so I dont think its got anything to do with that. I am more likely to believe that it would have something to do with the fact that I put on an ultra cycles 2 into 1 pipe that I bought this winter. It does have a baffle in it and I used new exhaust gaskets. It has the stock air setup. When I tightened the flanges back down, the nuts bottomed out against the exhaust ports, which makes me think that it did not make a tight seal and it could possibly be that there is a leak. Also I read a lot about fuel knock being a problem. I put in just under a gallon of the fuel I took out of the tank before I painted, just to get me to the gas station, so it was old gas, but then I filled up with 93. The bike is running great with the new pipe, no backfiring or popping on decel, and it is not sluggish. It is just this knock that concerns me. Any help?
     
  2. R.Bingham

    R.Bingham Active Member

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    Another possibility is a loose compensating sprocket nut. It will make an intermittent rattle or knocking also.
     
  3. saintNH

    saintNH Member

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    When I bought the bike last year it had the stock headers with slip ons, and it ran great. So when I put the 2 into 1 on I wanted to see if I could get away just swapping the pipe without changing anything else, but I will try the octane booster to see if that helps and if it does I will change the air cleaner. I am running the stock ECU, but Im not sure if it has had the stage 1 flash done or not. Is there a way to tell? And does this pre-detonation knock do any damage?
     
  4. Jack Klarich

    Jack Klarich Expert Member

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    Ping And Detonation - Harley Davidson Community have a read here
     
  5. Hoople

    Hoople Account Removed

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    If it is actual detonation and it is left unattended, it sure will. Detonation is bad stuff.
     
  6. glider

    glider Veteran Member

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    It can do anything from eating your spark plugs to holing your pistons.

    [​IMG]
     
  7. wilks3

    wilks3 Junior Member

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    Isn't spark knock caused by not enough octane for engine compression? I wouldn't think engine would spark knock because stock air cleaner/ECU is still being used. I would lean toward bad fuel still causing knock. Just my thoughts....
    wilks3
     
  8. wilks3

    wilks3 Junior Member

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    Stage 1 retards timing? I thought Dobeck was fuel mixture only.
    Last summer I got 2 bad loads of "93" fuel. I asked truck driver at gas station how much premium 93 he drops off each time he comes. About every 4th or 5th time, and only around 1000 gallons! So the premium in gas tanks can be anywhere from 90 to 120 days old! And it ain't that fresh.
    I would run some more fresh gas though and see what happens.
    wilks3
     
  9. wilks3

    wilks3 Junior Member

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    Thats true, too lean will cause detonation by cylinder running too hot.
    saintNH said he put about a gallon of old gas in and the rest 93, if 93 was not fresh he would have problem as described. He already has approximately 20% bad fuel in it, which is not good. New pipe has baffle still in it and with stock AC I just didn't think A/F mixture would be that way off, maybe is though. Another tank or two just to be sure.
    wilks3
     
  10. saintNH

    saintNH Member

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    We are having pretty lousy weather here for the next few days so it might take a few to test the octane booster. I will let you know as soon as I can.

    I talked to my local mechanic today(not the dealership) and he recommended that i do the stage 1 intake and get the flash done and he thinks that may take care of it. I am pretty sure that I should do this at some point anyway so why not now and see if it does take care of it. I was looking up the stage 1 air intake kit and I thought it was going to have a new housing for the air cleaner with more holes in it. All I saw was the filter and a plate and some mounting hardware. Are there more parts I will need to do this?
    [​IMG]
     
    Last edited by a moderator: May 3, 2011