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Thread: knocking sound maybe from primary

  1. #1
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    Hey guys, so recently I've noticed a slight knocking sound, not like a hard knock. Anyways I have a friend that works on Buell's when they come into the HD dealer. So i swallowed my pride and walked in, so I tell my buddy what's going on and him an a few other guys said. "It could just be the engine sprocket NUT is a little loose. So today I took off the primary cover, everything looks great ] and the NUT is super tight I event tried to tighten it, wouldn't budge.
    So now I don't know what to do. Before this problem every now an again I was getting a false neutral, shifting up from 2nd to 3rd. Not all the time though
    PLEASE help give me some guidance.. Thanx, DiRT

  2. #2
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    Adjust your primary chain to specs. And that NUT is torqued to 250 lb/ft!! If the knock continues, then let's reassess the problem. It's very common to get a false neutral from 1st to 2nd...not as much 2nd to 3rd, but can happen. Make sure your primary chain is adjusted properly and adjust your clutch.

  3. #3
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    Adjust the chain and clutch. Instructions are in the manual & on YouTube I believe

  4. #4
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    thanx guys I've done both things, but it kept doing it. I'm gonna put it back together and see what happens. If it's still doing it I hvae a feeling it's the crank, or rod bearings. but I'm not getting much metal in my oil or primary.

  5. #5
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    Not much metal!?! Any metal you can see is berry, berry, bad

    You need to lock the crank in place to torque it enough. Jeremy Clarkson would say 250ft-lbs is a lot of torques:D

    A low, loud knock (like rapping your knuckles on a countertop) that gets louder and higher pitched with RPM 1knock/per rev is usually a rod.

    The same sound with more rapid knocks is usually crank (but more rare in my experience with roller bearing cranks)

    Post a vid of it running. i-phone mic's suck, but move it around a bit.

  6. #6
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    love the Jeremy Clarkson quote!! I haven't put it back together yet. Had a trip planned to Bass Pro to get a new Bow. But fingers crossed after primary cover back on, fresh oil in primary an engine an then no more noise. thats my hope, it really isn't a loud or hard sound. I've been around plenty of knocking engines , so i got high hopes!

  7. #7
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    small shards of metal are fairly common in the primary...it's typically from the starter and ring gear engaging. just so you dont freak out...it happens

  8. #8
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    ya the magnet on the plug catched all of that, I'm just glad there weren't any big chunks!

  9. #9
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    I'm having this same issue on my 06 xb12ss. I currently have the primary off and everything out. My nut was torqued to 250 ft lbs, chain was adjusted correctly, and shows no scaring on the cover from the chain rubbing. I have been told that the 05 and 06 models were notorious for the crank pin wearing the plating off and causing further damage. I would tell you to try the same thing I did, turn the motor over at the crank to see if you can feel or hear anything internally. I'm still not finding any issues on my bike if anyone has any other suggestions. If not, my motor will be coming out and rebuilt. If it does come to that the only good thing is I will be using this excuse to put cams, heads, and making it a 1250...

  10. #10
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    I spoke with Dirt several times, through random chain of events he discovered his header had come loose from the pipe after the front exhaust mount bolt had fallen out.

    First thing everyone should check when hearing a noise is the header nuts and studs. It's happened to several people.


    ^ 05 had a string of quality control bearing issues. 06 is not known to have issues to my knowledge.

    Adjust primary, you can hear a bad rod bearing turning motor by hand. It's a loud thud every time you rock motor back and forth without spark plugs in.
    Other possibility is the piston bearing or a bad lifter.



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