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Latest post Sun, Apr 8 2018 5:30 PM by andy2175m4. 35 replies.
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  • Sun, Jan 21 2018 9:19 AM

    • andy2175m4
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    where is this loud noise in sporster engine ?

    I have 79 sportster XLS, 18,000 miles,  and it's making this noise in the engine, a loud tapping sound like a really loose push rod,

    If this was a car engine, you'd say it soundled like a bad hydraulic lifter, but this engine has solid roller lifters

    with a hose, the sound is coming from the center of the rear cylinder,  a rattling sound

    so far i have check the following with no results,

    removed, inspected, and set clearance on all 4 push rods, all good, but noise still there

    removed front and rear rocker boxes, no wear or slop in any rocker arms, no broken or missing rocker arm endplay springs

    removed all 4 lifters, no wear or problems

    checked 4 cams for lobe wear and end, play all is good

    removed rear head, cylinder, piston, and wrist pin, some corrosion etching of the bore but piston shows almost no, wear fits tight

    valves look good, stem tips show even wear, no broken valve springs, no loose spring keepers, no stuck valves

    no play in wrist pin, rod end play in crankshaft is .010"  well in spec,

    what else can I check ? 

    i cannot figure this out,  everything inside the engine looks great, but that noise is loud.  I have disassembled engines that were much more worn inside and did not make such a loud noise,  its a mystery, 

    TIA for your ideas !

  • Sun, Jan 21 2018 9:58 AM In reply to

    • FX
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    Re: where is this loud noise in sporster engine ?

    I'm suspecting maybe a rod knock. You have to grab the rod with both hands and check it for up, and down movement. Hold it centered, as you'll get some side rocking motion (that's okay), you have to eliminate that rocking feel, and the crank turning...

    FX

    Don't force it, get a bigger hammer.

  • Sun, Jan 21 2018 10:20 AM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

    hi FX thanks for the reply

    I did check the rod,  it has no movement up or down, not a trace,  the end play is .010"  well in spec,   the big rod end is very tight,  like new

     

  • Sun, Jan 21 2018 10:50 AM In reply to

    • Ironhead
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    Re: where is this loud noise in sporster engine ?

    Andy - you mentioned you pulled the rear jug off and checked the valves, piston, rod - did you do the same to the front one?

    any history on the bike that you can share?  is this a new-2-U bike or a friends or something you have had for a while?  has it been ridden regularly and this noise seems to be getting louder or just suddenly started happening or has it been sitting for a while?

    The first tool out of the box should be the "book"  Geeked

  • Sun, Jan 21 2018 11:16 AM In reply to

    • FX
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    Re: where is this loud noise in sporster engine ?

    Andy, since the noise seems at the rear of the engine, that's where the transmission/clutches are. Maybe transmission main shaft rattling, and the sound is radiating through the block...Since it sounds like the engine is still apart, you'll have to get into the primary to check that...If the engine is back together, or did you by any chance check the noise with it running, in gear, brakes on, slipping the clutch. if the noise goes away, or changes, then the problem is in the drive...

    FX

    Don't force it, get a bigger hammer.

  • Sun, Jan 21 2018 12:27 PM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

    The bike is new to me.  It did not run when I got it,  so I re-gasketed the carb, and replaced the ignition system, and now it starts right up.

    I don't really have any history on the bike, other than it sat in some guy's back yard for 15 or 20 years, and the 18,000 miles on the odometer.  A true barn find. 

    The primary and the transmission appear to be fine,  no noise from the primary or the gearbox,  seems to be just in the rear cylinder, 

    Whats odd is that every part I have inspected looks very good,  nothing broken I can find, and no engine wear other than what you would expect for 18,000 miles.

    I did not pull the front cyliner yet but that's next.  There is no noise though coming from the front cylinder.

    Also I was going to remove the rocker arm shaft springs and replace with spacers, per a post I found about racing ironheads, but my lathe is in pieces right now so making parts is a problem.

     

     

  • Sun, Jan 21 2018 12:45 PM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

    2 more details

    1. the clutch basket had separated from its hub,  still worked but was extremely noisey, that was a simple fix, new clutch basket,  when that noise was gone I noticed the tap tap tap, 

    2. also I changed the oil of course, it was somewhat dirty but had no visible flakes of metal or other evidence of internal damage.

     

  • Sun, Jan 21 2018 12:47 PM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

    the noise does not go away, clutch in, or clutch out,  in gear, or in neutral, noise is always there and is the same.  so I dont think it's in the drivetrain.

     

  • Sun, Jan 21 2018 4:06 PM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

     

    this time I waited for the eingine get pretty hot to see what happens

    After it got hot, the idle stabilized to a typical  "potato-potato" rhythm, and the tapping noise got noticeably quieter, 

    I decided to call it cold engine piston slap and just declare victory.  No more tearing it down.

    I am going to change the oil to straight 50 wt  VR1 Valvoline racing oil (apparently an oil thats popular now for HD's) and see if it gets even quieter,

     

  • Sun, Jan 21 2018 4:18 PM In reply to

    Re: where is this loud noise in sporster engine ?

    in my opinion, the switch to racing oil would not be a good idea. valvoline racing oil is formulated to reduce foaming [to maintain oil pressure] and absorbing excess fuel, not neccessarily for good lubrication. i like valvoline oil, but for street applications, the racing formulation might not be the best choice

     

  • Sun, Jan 21 2018 4:38 PM In reply to

    • FX
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    Re: where is this loud noise in sporster engine ?

    Andy, put an oil gauge on it, and see what the pressure is. From sitting for so long outside and with oil contamination, the oil pump may be bad. The engine may not be getting enough oil pressure at rpm. I agree with Sfranta (Steve) on the racing oil. You can run any good 50 wt. motorcycle oil for air cooled engines in it, or even 20/50 if you'll be running in cool/cold weather...Let us know how yer do'n...

    FX

    Don't force it, get a bigger hammer.

  • Sun, Jan 21 2018 5:41 PM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

    The oil pump is fine, the oil flow to the top end is good,  when I lower the rod covers, engine running, to check the rods,  the oil just pours out of the rocker boxes.

    I guess you guys are right about the VR1 50w oil though,  I can go get some regular 50w and save the VR1 for another day,

     

    The real reson I pulled the jug off was since the rear cylinder was making all the noise I wanted to see if it was the wrist pin, or the small end, or the big end of the rod, was bad,  

    one of those would ruin my day, if I had to pull the crank.  But the rod and crank are in great shape,

    Since I was mostly interested in seeing about the rod and crank,  I did not mic the piston or check the cylinder for out of round, I just looked at the rings, piston, and bore, and they all looked fine. 

    So next time I pull the jugs I will mic the pistons and bore, and see WTF and verify its piston slap,

     

     

  • Mon, Jan 22 2018 5:52 AM In reply to

    • FX
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    Re: where is this loud noise in sporster engine ?

    You would have seen noticable gouging on the piston skirt, and cyl. wall if the noise was piston slap...Could the noise be the breather puffing? Where is it venting?

    FX

    Don't force it, get a bigger hammer.

  • Mon, Jan 22 2018 6:30 AM In reply to

    • Ironhead
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    Re: where is this loud noise in sporster engine ?

    andy2175m4:

     

    this time I waited for the eingine get pretty hot to see what happens

    After it got hot, the idle stabilized to a typical  "potato-potato" rhythm, and the tapping noise got noticeably quieter, 

    I decided to call it cold engine piston slap and just declare victory.  No more tearing it down.

    I am going to change the oil to straight 50 wt  VR1 Valvoline racing oil (apparently an oil thats popular now for HD's) and see if it gets even quieter,

     

    Personally, I think it is in the lifter system - solid lifters that have a slight bit of play when cold (how they are to be adjusted) that as it heats up, the metals expand and remove most of the play.

    Perhaps try adding 1 or 2 "nut faces" more tension (concept of a nut having "6 faces")?

    The first tool out of the box should be the "book"  Geeked

  • Mon, Jan 22 2018 9:49 AM In reply to

    • andy2175m4
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    Re: where is this loud noise in sporster engine ?

    More preload in the push rods does not change the noise.

    I used a heater hose to listen to the rocker boxes, rod ends, and lifters, and they all sound normal, just a moderate ticking sound, the same on the front and rear cylinder,  I inspected all the rods, lifters, rocker arms, and valve stem tips and all are good.

    there is some wear on the noisy rear piston, but its not drastic,  just some rubbing on the surface coating,  maybe I am under-estimating the damage on that piston, but I did not take a picture so next time I will.

    there are marks on the block showing the base gasket was scraped and replaced at one time on the rear cylinder so someone else was into that engine once, but no way to tell 'til I mic the bore.

    The sound is coming from the middle of the jug so it must be the one piston,  the jug on the front cylinder has the same sound but much quieter,  so I am pretty sure its the rear cylinder and piston,  I did not mic the rear bore and piston becuase I was in a hurry to just check the rod, and eliminate a lower end problem, which I did.   The piston is easy to fix,  but not the crank.  so the end game will be to pull the rear jug once more and mic the bore and piston.

    there is a you tube video of an evo sportster where the guy accidentally put std bore pistons into the engine with .020-over jugs, and the noise was loud, and sounds the same as the rear cylinder on my ironhead.  When he put in matching pistons and jugs, sound was completely gone.

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