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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Hi All, I had a pair of twin cam cylinders bored from Ø3.750" to Ø3.875" and when I assembled the pistons are noticeably out of square to the deck, like .020 difference from front to back and both cylinders are the same. The cylinders were the originals off of my '06 FLHTCI so I'm thinking it's an issue with the shop that bored them.
I think to determine that you have in fact cylinders bored out of square you need to measure a top location of the bore and a lower location of the bore. Someone with a mill that has a DRO can measure top and bottom to see if it's straight.
Keep in mind there are some aftermarket pistons that have an offset pin that may give the appearance of an uneven piston height when rocked in the bore.
I use a high quality digital protractor to measure bore angle. Not as precise as a mill, but it does the job.
Ya paid for a cylinder bore job. Sounds like that what ya got. Did ya get charged for cylinder decking???? Assemble with old head gaskets but don't torque em down. WaLa no gap!!! NOW, sit down with a cold beer and relax.
A cylinder can be bored incorrectly, but that doesn't match what you describe. Mabey a few pictures of what you have with cylinder installed will help determine what is happening.
To have 0.020 mismatch at the cylinder bore you'd have to have 0.030 at least on the boring bar.. IMO that would be hard to do..
Pistons are cam and taper ground. Have you simply tried to push the high spot down and checked again? The upper part of the pistons can rock quite a bit, especially without the rings on..
To have 0.020 mismatch at the cylinder bore you'd have to have 0.030 at least on the boring bar.. IMO that would be hard to do..
Pistons are cam and taper ground. Have you simply tried to push the high spot down and checked again? The upper part of the pistons can rock quite a bit, especially without the rings on..
hummmmmm????
were torque plates involved in this issue?
most pistons are not trunk type, aka, same top to bottom, they have taper.
i have a set of cyl, heads and pistons at stock that were a take off with low miles. i have no need for them.
Cylinder bore out of square
