Wannabriden's D Port Re-Port

Ok guys....
Wife had eye surgery last Wednesday.
She has had some complications and as I am her caretaker my shop time has been limited.
She is on the road to recovery but she will be seeing the doctor on a daily basis for the near future.
She is becoming a bit more self sufficient so I should be able to get back to some very much needed shop time.
Update...

First of all I would like to thank gggGary for sending me a junk head to explore limits with.
I will be sharing all the information gathered with the community once I am at that point.

I still have to assemble my incline manometer. I have it all and since my wife's doctor appt is early tomorrow I am certain I can complete it.
Then the bench calibration/tuning can begin. Then at last the testing of the head.
In the meantime I have managed to sneak parts of my shop into the kitchen to accomplish a few things after the wife was put to bed.
This is ALL about information gathering at this point.
I cc'd the combustion chambers on Garrett's head. His cumbustion chambers appear untouched.
I measured them both at 58.8cc
Looking into the manuals I could find nothing that matched that measurement.
I did find 3 different cc values:
78 650E - 44.18cc
80 650G - 42.5cc
83 650SE - 43.6cc
Obviously these values are vastly different than what I measured.
The junk head that gggGary sent me was loaded and had one cylinder that sealed so I tested it as well.
Also 58.8cc. I reached out to a couple of members (gggGary was one) to try and better understand the discrepancy.
The picture gggGary posted are those I sent him
He reached out to Dennis (@kopcicle ) to join the thread. Dennis was kind enough to message me and we had very good very long conversation about many many different things. VERY Knowledgeable, very informative, and gracious enough to share some of that knowledge.
Reminded me greatly of my conversations with Michael "Mercury" Morse. Truthfully 2 of the most interesting conversations I have had the pleasure of having regarding the xs650. Many many illuminating points to contemplate. Dennis explained that Yamaha included the piston dome in the calculation instead of specifying the actual chamber (flat plate) measurement. Our conversation went waaaay beyond that I want to thank Dennis for taking the time to share some of his knowledge while helping to expand mine on a variety of subjects.

I think perhaps that anyone doing a build where they are changing out the pistons and have a desire or need to calculate their CR should be using the 58.8cc volume in place of the printed specification.

Of course it was the intake ports that I was really interested in.
I measured the one STOCK intake port that I had available with valves that sealed.
(This will be confirmed with my other stock head once the valves have been reinstalled)
The STOCK head intake port measured 79.6cc
Garrett's D Port measured:
Left - 77.2cc
Right - 82.8cc
That's about a 7% difference.
The ports should be balanced to 1%
Soooo.... Issues beyond the delamination.
Interestingly the stock head's value is nearly centered between the two.
I am curious to see what differences the flowbench will reveal as well.
Stay tuned. It is coming VERY soon. Regardless of what life throws at me.
 
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A lot going on here so hoping it isn't confusing.
Earlier I pulled molds on Garrett's D Port and just pulled the molds from my Stock head.
I am going to show some comparisons...
I have found that quite often they can be used as a visual aid to get a better understanding.
In all the pics the STOCK head is on the left or on top. The stock head's port mold hasn't been cleaned up yet.. but it's not a beauty pageant.

Notice the bulge just after the valve stem on the stock compared to the straighter lined port from the D Port head.
 

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In the attached pics notice how much of the valve guide boss has been removed what we are seeing as a depression on the stock port is in reality a mountain inside the port. They smoothed this pretty good looking at it here.
 

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In the attached pics I am just pointing to where the same starting spot is on these. Stock is again on the left. Easy reference as the stock mold hasn't been cleaned
 

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Notice the short turn. How D Port head has a smoother transition compared to the more abrupt sharper turn on the stock mold

Oddly the two different shapes are within 3.2cc
Widening the floor adds CCs.
Raising the floor takes away CCs.
 

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might answer a question you have. Dennis knew immediately....
https://www.wikihow.com/Calculate-Compression-Ratio
Excellent link gggGary.
That is exactly how I do the calculations.
I wanted to point out the difference between the actual measured combustion chamber CCs and the book specifications. Because Yamaha chose to subtract the piston dome from the actual chamber CCs in writing the spec (per Dennis); for someone changing the pistons, that spec becomes erroneous. Your link Step 6:

----------
6
Determine the combustion chamber volume in cubic centimeters. Use the specs from the manufacturer to find this measurement.

*** USE THE SPECS FROM THE MANUFACTURER TO FIND THIS MEASUREMENT ***
-----------

The Yamaha spec appears to be incorrect unless one is using a piston with the same dome volume that was used by Yamaha to create that specification. Anyone doing a piston change and using the book specifications will no doubt result in an actual CR lower than expected.
44cc spec compared to 58cc actual is over 30%.
That is a huge variation.
 
Disclaimer; I know diddly squat about hotrodding motors.

Getting to the actual compression ratio is more involved for sure.
The net head volume @ TDC is required.
No way to do that without measuring piston "dome" volume to subtract it from gross head volume.
But comparing head volumes is useful without that step.
Comparing volume left to right is not something I've seen done hereabouts. :umm:
Is it an issue on XS heads "as built"? if so, how to correct it?
Yamaha's "speed manual" mentions smoothing the combusion chamber ridge at the valve pocket but to keep material removal at a minimum.
 
Yes indeed the piston dome has to be subtracted from gross head volume. Personally I measure all the values. But that's just me. There is no real reason to measure and compare the left and right chamber provided they haven't been modified. But it doesn't take but a couple of minutes once you are setup to measure the first one. So I just do it.
Yes I have that speed manual and can post it here if someone is interested. I think it is probably already available someplace on the site.
 
I always check both.
So far 3 different chambers , 2 different heads.
Same exact measurement.
I have 5 other chambers to test here once the valves are lapped and the chambers are sealed. Have a better idea if it's an issue once I have tested them.
 
Latest update..
Was testing the bench, preparing to make a video simply demonstrating the process I will be using on my flowbench. Unfortunately had a component fail gloriously.
I had intended to use an inline anemometer calibrated for CFM. It was working quite well until I went Tim "Tool Time" Taylor on it.
Anyways, the resulting fiasco is attached.
The vacuum sucked the fan blades right off.
Left one little nub.
I have ordered a differential pressure meter which I had intended to add later anyway.
I also ordered a hot wire anemometer to make it easier with calibration as well as taking measurements. They should both arrive between Wednesday and Friday of next week. I have a few mods to the bench (for the Diff Pressure) to accomplish before they do. Plenty to stay busy with in the meantime. Finish cleaning/lapping valves to seal the stock head and get it ready to test. Make a locating tool for taking measurements within the port and opening up the junk head to see those limitations.
I am hoping to still make a video showing the process hopefully tomorrow although there will be no ability to measure the flow. It should give a better understanding for those still trying to picture the process.
 

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No video since I can't actually calibrate the bench anyway without the meters which won't be here until the end of the week. Did get everything connected and operational. Took a few pics.
The vacuum side of the inclined manometer is connected through the spark hole just for ease for this test. The vacuum will be pulled in different locations once actual testing is done.
also included a pic of a flowball. They will be used to map the intake ports for turbulence/dead zones. Much more about that once we get started. Hope everyone enjoyed the weekend.
 

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I do like the clear tube so that you an visualise swirl if you use smoke. How are you going to generate the smoke?
 
Hey signal.
I am planning to use incense or punk sticks.
I'll see what works best.
The tube isn't nearly as clear as I thought it would be when I ordered it. I'll be able to use my boroscope to see inside the chamber as well.
 
Some valves cleaned...
Just cleaned not polished yet.
Loading up the stock head for testing.
Will lap them in tomorrow, clean the head, install the valves and and test the seal.
Then CC everything so it will be ready to test alongside Garrett's D Port
once the meters arrive the end of this week and the bench is finally calibrated.

Also drilled a valve to measure velocity from the port side of the valve.
I will have the ability to clock it to different positions.
Still needs the tube cut and epoxied in but you get the idea.

Included some pics but there's nothing to see here yet.
 

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