Overbore; Ensuring the right stuff

cbx6ss · Post by **cbx6ss** » Wed Sep 10, 2008 7:56 pm

So I'm somewhere in the middle of an overbore, and valve job. I am preparing to farm out the overbore and hone. I just received a set of brand new 1st over (.025?) pistons from Honda. The original pistons measured as follows:

ORIGINALS
2.5383
2.5384
2.5383
2.5385
2.5385
2.5385

When I measured the new ones I got:

NEW ("25")
2.5480 (all)

Increase of .010 diameter from original

I expected 2.538 + .025 = 2.563

What gives?

Is this right? Am I missing something?

/r
Brad

EMS · Post by **EMS** » Wed Sep 10, 2008 8:59 pm

I am a little confused by all these numbers, especially as you mix metric and standard measurements. The Honda CBX is a metric bike. The piston oversizes were usually identified by mm oversize 0.25mm, 0.5mm,0.75mm and 1mm. I don't know where you have the 0.025 (inch?) oversize dimension from.
Your old pistons measure 2.535 inches = 64.46mm
The new ones are 2.548 inches = 64.72mm
Difference = +0.26mm = 1st over

cbx6ss · Post by **cbx6ss** » Wed Sep 10, 2008 9:13 pm

Got it! I went back to the parts web site to check and sure enough they offer:
.25
.50
.75
1.00

Maybe if the U.S. had gone metric (in the 70's?) like we were supposed to, that would be one less thing confusing me today. Instead we have both measures on everything today.
Thank you all!
Regards,
Brad

-----Original Message-----
From: The Becks [mailto:T_CBECK@Charleston.net]
Sent: Wednesday, September 10, 2008 8:38 PM
To: Brad Eyre
Subject: Re: Overbore continued...

0.25mm, or about .01 inches.

Tony Beck
-----Original Message-----
From: owner-cbx@ucdavis.edu [mailto:owner-cbx@ucdavis.edu] On Behalf Of XCBMW@aol.com
Sent: Wednesday, September 10, 2008 8:20 PM
To: eyrepb@comcast.net; cbx@ucdavis.edu
Subject: Re: Overbore continued...

In a message dated 9/10/08 7:54:55 PM Eastern Daylight Time, eyrepb@comcast.net writes:

<<I>>

Sounds like the 2.538 is inches and the overbore is .25mm

Paul
NJ

Don #6141 · Post by **Don #6141** » Thu Sep 11, 2008 11:05 am

I remember once long ago reading a review on a new phono cartridge. It had a tracking force measured in grams, an antiskating force measured in dynes per centimeter squared and mounting holes 1/2 inch apart. I think the reviewer said it best - "Only in America!"

Don

EMS · Post by **EMS** » Thu Sep 11, 2008 11:31 am

Don #6141 wrote:I remember once long ago reading a review on a new phono cartridge. It had a tracking force measured in grams, an antiskating force measured in dynes per centimeter squared and mounting holes 1/2 inch apart. I think the reviewer said it best - "Only in America!"

Don

A Shure?

Rick Pope · Post by **Rick Pope** » Thu Sep 11, 2008 7:01 pm

Sheesh. Got 'em on both of my Dual turntables.. We really are old.

alimey4u2 · Post by **alimey4u2** » Thu Sep 11, 2008 7:28 pm

"Dual" deck & "Precept" cartridge here, just purchased two styli for a kings randsom which should last me in my dotage. Not being selfish, I left one ( the last) for someone else to buy....