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Old 05-06-2009, 12:32 PM   #1 (permalink)
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Question Piston direction

I am doing a 95" upgrade to my TC88 99 FLHT. Since this is all new to me and I have never done anything like this before I sent my cylinders out and had them bored and fitted with SE 10.25 to 1 pistions.
They set the rings and installed the pistons in the cylinders so that all I had to do was push the piston down far enough to get the wrist pin in the connecting rod and install the circlip. What I noticed is after I already mounted the cylinders the arrows on the top of the pistons are pointing in the wrong direction according to the Harley service manual. I can't see any differance in the piston top so I was wondering what is the reason for the arrows. I am using the stock heads that have been ported. Should I take it all apart and rotate the pistons 180 degrees? Thanks.
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Old 05-06-2009, 01:21 PM   #2 (permalink)
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I would say that at minimum, you should turn the pistons around so the ring gap is in the correct location.

However, a more experienced builder may say it's ok to leave as is....
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Old 05-06-2009, 01:38 PM   #3 (permalink)
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the pistons have a offset wrist hole to help quiet piston slap...turn them around....
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Old 05-06-2009, 03:40 PM   #4 (permalink)
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the fly cuts go up... no jus playin.. like they said turn them around.
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Old 05-06-2009, 04:58 PM   #5 (permalink)
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First of all, what did the manual show and which way are they pointing now? Never assume the manual is 100% correct.
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Old 05-06-2009, 05:03 PM   #6 (permalink)
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The manual says the arrows should point toward the front of the motor and they are pointing toward the back.
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Old 05-06-2009, 05:27 PM   #7 (permalink)
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They need to point toward the front.
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Old 05-06-2009, 05:34 PM   #8 (permalink)
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Yup, the manual is correct, now go give the guy that put them in backwards a swift kick in the groin.
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Old 05-06-2009, 05:41 PM   #9 (permalink)
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I'm no mechanic, but I think they go up and down.
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Old 05-06-2009, 06:43 PM   #10 (permalink)
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Quote:
Originally Posted by Lance03 View Post
I'm no mechanic, but I think they go up and down.
Hahahaha, you musta stayed at a holiday in!
I was gunna say that it would be easier to just spin the cylinder around but I didnt want to sound like you did.

Like everyone said, point the arrows forward ...................
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Old 05-06-2009, 06:52 PM   #11 (permalink)
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Thanks guys for all your input. I would love to give him a swift kick in the ass if he wasn't so far away. Next time I am going to find someone local. Looks like I will be removing cylinders and rotating pistons. Thanks again!
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Old 05-07-2009, 04:36 AM   #12 (permalink)
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I just installed KB forged pistons with offset pins...if my memory serves me (???) the instructions showed the arrows on the pistons pointing rearward? Visit the piston manufactures web site or call their tech before you take a leap of faith...
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Old 05-07-2009, 05:08 AM   #13 (permalink)
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midnight sporty mentioned fly cut. Some pistons do have a larger cut where the intake valve is. Intake is larger than exhaust. Make sure larger relief is under the intake. The cylinder fins are relieved on one side for the push rod tubes. Make sure they're not turned 180. Don't mean to question you're ability, but sometimes it's the little things that get by.
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Old 05-07-2009, 05:56 AM   #14 (permalink)
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what he said
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Old 05-07-2009, 11:51 AM   #15 (permalink)
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I confirmed with Harley the SE pistons point forward just like the stock pistons. Thanks
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