Print Page - 103 Compression Height

Title: 103 Compression Height
Post by: Cowtowner on January 19, 2021, 09:08:14 AM

I've searched but can't find an answer - what is the compression height (piston height) of a 103 OEM 3.875 cast piston?

I'm looking at going with a higher compression forged piston (instead of milling my heads and using my cast OEM pistons, which is my current plan) and noticed that CP publishes compression heights, and I'm curious what a couple of their part numbers would do (ballpark) to my current deck height, without having it on my bike and measuring it.

Title: Re: 103 Compression Height
Post by: 04rkryder on January 19, 2021, 03:24:24 PM

Using the following values:
Cylinder length= 4.937
Crank c/l to case deck= 6.000
Connecting Rod Length= 7.658
Stroke=4.375

A piston with a C/H of 1.092 will get a calculated deck height= 0.000

Title: Re: 103 Compression Height
Post by: Cowtowner on January 19, 2021, 04:05:16 PM

Thanks, I appreciate it.

Title: Re: 103 Compression Height
Post by: Don D on January 20, 2021, 06:43:33 AM

Good information but hypothetical. Real world variation forces measurements.

Title: Re: 103 Compression Height
Post by: 04rkryder on January 20, 2021, 06:51:49 AM

That's why I said calculated. :SM: It is just a starting point..

Title: Re: 103 Compression Height
Post by: N-gin on February 27, 2021, 06:03:57 AM

I found the 103 cast piston to be .005 down.
This is purchasing new cast pistons and boring and honing ebay 96 take offs.
KB, Wiesco, I've found to be .010 down.
I don't recall the measurements but I do remember measuring and posting here.
Had to be 6-7 years ago.

Title: Re: 103 Compression Height
Post by: RTMike on February 27, 2021, 08:22:23 AM

Twin Cam standard deck height is 1.092

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Technical Forums => Twin Cam => Topic started by: Cowtowner on January 19, 2021, 09:08:14 AM