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Author Topic: tore my motor apart and think i found what was making the piston noise  (Read 1506 times)

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panhead1

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tore my motor apart and think i found what was making the piston noise
« on: July 18, 2014, 02:41:07 PM »
Got my rear head off today and found these marks on the rear part of the cylinder.  Guessing this is what is making the knocking sound. The marks are very faint on the front part of the cylinder.  Gonna pull the jug off and see what else i can find and what caused this. 
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panhead1

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #1 on: July 18, 2014, 02:47:57 PM »
a different pic
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Ghost__Rider

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #2 on: July 18, 2014, 03:06:46 PM »
Yes sir, that would be a gaulded piston. Excessive heat usually causes this.
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panhead1

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #3 on: July 18, 2014, 03:47:12 PM »
Thought i would find some bad stuff on the piston.  Whats weird is the wear mark isn't in the center of the piston.  i have a couple pics of the front and back of the piston.
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panhead1

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #4 on: July 18, 2014, 03:47:55 PM »
this is the front of the piston
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GMR-PERFORMANCE

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #5 on: July 19, 2014, 08:34:58 AM »
On the pics of the piston you can see where combustion gases have made their way past both upper rings to the oil control ring pack. Any time that happens , you are seeing that the ring pack was not sealing. When the  swap from the stock pistons for these domes where the cylinders bored and honed to fit the new piston? Or just a light de glaze and then installed? Being that the upper edge of the piston has no marks I do not think its heat that created thisl. Looking the piston I can see where carbon is missing but it has not touched down on the cylinder. Top of the piston coated in oil, gases pack the ring  pack, golden color to cylinder all point to fitment.  Better pictures of the dome might help and chamber of the head. The flash can make things look different then it really is. Now once it started to stick then some heat would have been induced into the piston.  Bummer ...
« Last Edit: July 19, 2014, 08:41:09 AM by GMR-PERFORMANCE »
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panhead1

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #6 on: July 19, 2014, 09:19:34 AM »
Ya i am not sure if it is fitment or my valve guides and seals leaking.  Has only 15k miles on it.  And looks like that.
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GMR-PERFORMANCE

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #7 on: July 19, 2014, 09:40:01 AM »
Where the cylinders bore to fit those pistons?
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panhead1

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #8 on: July 19, 2014, 09:41:30 AM »
Yep
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HD Street Performance

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Re: tore my motor apart and think i found what was making the piston noise
« Reply #9 on: July 19, 2014, 10:21:31 AM »
The remnants of a ridge tells me the cylinders were honed not bored and honed. Put them in plates and verify the fit. I think that is close to the core of the problem. The hone job doesn't look too good either. It is not a good idea to use a fixed hone on a rering job and that said the bore needs to be relatively right to begin with. From there I prefer and have had better luck with a fine ball hone (325) in an AN power feed machine. Virtually no material is removed but a hone pattern is established.
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