No you don't get it... The manufacturer is basing their cr@.000" deck. They have to have a common number...

 

The problem is you must ASSUME some of the dimensions when doing a design and HD sucks when it comes to repeating from engine to engine. It is not uncommon to take a TC or M8 apart and bolt the cylinder on and find the piston at TDC down the cylinder 0.012" - 0.016". Then the cylinder head volumes are all over the place. Back when we worked with the factory, we got them to build three engines for a test we were to do for them. No one knew except the engine builder which was which but they were all built from the same parts. So one engine was built for high compression so he checked heads and got the smallest volume chambers. longest rods and longest crank stroke. Then assembled the engine and used the shortest cylinders. ALL parts were within Factory specifications for each part. The second engine was the low compression build which was the same as the high compression but with all the dimensions the other way. The third engine was built like any HD dealer builds, meaning, grab the parts wash everything up and cleanly assemble it. All engines once complete were shipped to us for testing. We used three identical bikes to install the engines and run all testing. Anyone want to guess at the results?

After we finished up the work the factory flew in to ride the bikes. Three engineers rode three bikes and loved them. Then I pulled the ECM's out and told them to install them in a different bike and go ride them again. The first test ride they were gone for a few hours, each ride after no more than 10 minutes and they were back in the shop swapping ECM's around again. Took them several tries to find which one, when in which bike, as i would not tell them. After that go around, new specifications were adopted as to how testing was to be done as they could not believe the results.

 

Very interesting Steve. Was that before or after they started doing closed loop?

 

Most any assembly line engines are not blueprinted and have so pretty large variations
No doubt the manufacturer of pistons picked a baseline to work from and that what we have to understand.
The Evo can have over 0.50 shave off a virgin head no problem and all the better for it.
Next as in my case , aftermarket cylinders and pistons is another caveat.
I have had to remove some material from the cylinder bases to get things correct.
So back to what caused me to write this thread as I chase my squish and other things ..Dont be too sure what you have without measuring

 

Throw me a bone here, what were the results? I'm not understanding the ECM swapping business.

 

Getting sidetracked here,,,,

 

Not surprised.......

 

I disagree. Steve's comment was based on the variability of construction tolerances of the HD engine, which is within the scope of your opening comment. I only asked him to expand on what he said.

Besides, isn't stimulating conversation, so long as it's within the subject matter origin, something that makes these public forums great?

Edit: Threads like this are far and few between. Way more stimulating to me than the same ol' BS like, "which oil should I use" or "which air dryer should I buy for my $40,000 CVO trailer queen?"

 

In the Essense of all things, engine theory tried and failed, ( I have had a few)
i have backed off from posting the crazy things i try and have tried on this engine. (and others)
The pix of the squish interested you and a couple others and that was it!
And thanx for that!
It woud be great if more hotrodders contributed ..But for most here on this forum, engine work is transparently
as boring as cold oatmealas there is not ever much of a response to what I and others post on that venue.
For most of these so-called bikers (bucket kickers) they have been ardently configured and trained to buy
the BS stage kits and installed at HD dealer.
In fact, when the post starts to stray to performance some will jump right on here start saying "if i wanted a performance bike" I would have ____________ whatever one!"
YET, there are hundreds of performance parts available to buy and dabble with ,. From tires, suspension and all kinds of engine up grades, transmissions, etc etc etc!
However, most of these guys gather around and talk about their favorite wax and retirement checks.
So YES it would be great if others would post their mistakes and success, what worked, what did not.
I would very much enjoy it too!

 

Speaking for me only, but it doesn't have much to do with the subject matter as I find that very interesting but has more to do with how you conduct yourself on this forum