Clacking noise

Discussion in 'Sportster Models' started by nhk750, May 17, 2010.

  1. nhk750

    nhk750 Active Member

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    Well, I had a wierd noise in my engine.

    It was a 70 deg F. day here in WA and I was idling a bit going through the park, so the bike was pretty warm. My fuel level was on the low side, but the light was not on yet. Bike has 5,000 miles on it and a fresh oil change with Synthetic oil and oil level is perfect with no leaks (except normal little seepage around valve cover like normaly does). I checked the plugs and they are looking good. Stage 1 mods, FUELPAK, V&H Straighshots, Screaming Eagle Heavy Breather intake, and everything tunned, running perfectly.

    OK, so there is the condition and build...

    When I left the park and accerated heavily, the top end of the engine (at least it sounded like the top end) made a clattering noise (kinda like a preignition knock) I have never heard this noise before and it concerned me. My bike is pretty noisey, so I had to accelerate hard a few times to confirm noise, but it sounds like a knocking noise you get on a car when you have cheap gas in it. My thoughts are I have possibly bad gas and since I am at the lower levels of the tank, maybe that is the cause.

    I havnt had a chance to fill it up with fresh gas yet, the last time I filled up was a month ago. I have never heard a bike make valve clatter noise before.
    Is this common with Harleys and bad gas or do I need to worry about something else more intense?

    I do push the bike hard sometimes, I like to accelerate hard and blow the cagers off the road, especially when they have thier windows down and are driving really slow...hehehehe....
     
  2. Hoople

    Hoople Account Removed

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    Sure sounds like a case of bad/ low octane gas to me. Before I started to worry or jumped into checking internals, I would dump the fuel and do a refill with the best fuel I could find. I bet the 10% alky flashed off and you were left with a very low octane blend of trash.
     
  3. BUBBIE

    BUBBIE Well-Known Member

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    If you take the bike up to speed But NOT twisting throttle Fast all the way but RPM's ending in same place, Does it make the noise? I'd say no.

    I would think the Full Twist on the throttle is what you did and it made the knock sensor work and retard' the spark (chip chip chip noise)....(my wording here) HD say in my Old book that the Rattle noise is normal when twisting throttle on hard and not spark-nock..

    Does the noise ONLY come on when full hard increase of throttle is demanded?

    agree with *Hoople... to refill tank with a good gas / 92 octane / brand name station!

    signed....BUBBIE
     
  4. nhk750

    nhk750 Active Member

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    Slow twist of throttle, no noise.

    Noise only comes on when full quick twist of throttle and under high torque.

    I am going to ride this tank out for another 40 miles then refill with fresh fuel and then see what happens. Hopefully it will stop raining here this weekend...
     
  5. Hoople

    Hoople Account Removed

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    That supports the poor fuel theory even more. When the throttle is twisted fast, there is not enough time for the Map sensor to react and tell the ECM what the spark timing should be under that given map pressure so it knocks..
    Even though it is a computer, that process does take time.

    Your going to be blending fuels for awhile if you refill going by the reserve light.
     
  6. BUBBIE

    BUBBIE Well-Known Member

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    HAHAhahahahahahahahahha........

    signed....BUBBIE:newsmile075:
     
  7. nhk750

    nhk750 Active Member

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    You must be in AZ right now. Our stupid never ending winter up here....
     
  8. RiffRaff

    RiffRaff Member

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    First, I'll stay in the thread by agreeing with the others that some fresh gas will probably clear things up for you.
    Next, I have to say Wow! A month on a tank! I know it rains a lot in Seattle but I'm happy when I don't have to fill up twice in an afternoon.
     
  9. cdn-bigfoot

    cdn-bigfoot Junior Member

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    Higher octane fuels are needed the lower in elevation you get. Seattle=Sea Level. Don't use anything less than a 92 octane EVER. And stay clear of Ethanol blended gas.
     
  10. pike1612

    pike1612 Member

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    Just a thought- i had the same thing happen to me and my rear cylinder exhaust vibrated loose from the manifold.(hence the nut backed off the stud)It would make a clattering sound at high rpm's.Probably not the case with you but it wont hurt to check:)