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Discussion Starter · #1 ·
the new bore size is 2.895" done by a shop that has done a number of 450's with these pistons, referred to as 12th overbore on the net, I calculate about 492 cc.
the rings fit nearly perfectly with probably .0005" gap, just enough to get them in. I will use the listed Honda gap but wonder

1/ best way to take material off -dremel tool I think?
2/ lean towards the larger end of the Honda gap tolerance more than the smaller or go in the middle?
3/ I realize it will wear and you can't glue the ground stuff back on... :)

replies appreciated,
brian
 

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I would go for the small end of the Honda spec, myself.
Be really careful using the Dremel for this - rings are softer than you might guess, and you can overshoot easily and remove too much material.

Don't ask how I know this.. :( :oops: :oops:
 

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Brian, for sure follow the recommended end gap spec. Tighter end gaps will lead to ring seizure or cylinder scuffing. To make sure the piston is perfectly square in the bore use the top of the piston to push the ring down about 1" then measure. I always use a file but a Dremel with a sanding disc will work too. Just be careful to remove any sharp edges that could hang up in the ring groove and make sure that you keep the end gap 90 degrees to the ring in both planes so the gap is consistent top to bottom and inside to outside. Good luck.

Edit, Bill it looks like we were typing at the same time and you type faster!! :)
 

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Discussion Starter · #4 ·
Re: best end gap, bore surface finish?

tbpmusic said:
I would go for the small end of the Honda spec, myself.
Be really careful using the Dremel for this - rings are softer than you might guess, and you can overshoot easily and remove too much material.

Don't ask how I know this.. :( :oops: :oops:
time for new fine file I think.......Also, a friend who had his bored by the same machine shop used a lot of oil till it was broken in, i believe it was because they honed the cylinder too fine for the old style cast iron one piece oil rings. What is the opinion on surface roughness for seating them? The finish is finer than any I have ever seen before and I would prefer to see more of a 45 degree slant on them.
Comments?
 

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Re: best end gap, bore surface finish?

beedub said:
time for new fine file I think.......Also, a friend who had his bored by the same machine shop used a lot of oil till it was broken in, i believe it was because they honed the cylinder too fine for the old style cast iron one piece oil rings. What is the opinion on surface roughness for seating them? The finish is finer than any I have ever seen before and I would prefer to see more of a 45 degree slant on them.
Comments?
That may be part of it - or it may be that some sort of assembly oil was used in the cylinders.
This can actually inhibit the seating in process.
Generally it's best to keep the cylinders dry - use just a little assembly oil on the very bottom of the piston skirt.
 

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Discussion Starter · #6 ·
Well i spoke with my favorite mechanic and auto machine shop guy; we all three agree :D the bore looks so fine it looks glazed. A case of beer later, my buddy Robert had a fine 45 degree hatch pattern done with an automatic Sunnen honing machine that can be set for pressure, angle etc. ring clearance slghtly increased but noe it looks they way I think it should be.
 
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