Changing Intake ports to a D shape for better flow.

I count 17/ 34 teeth... Stock euro is 17/33
What's US stock?

17/34 was stock US on '83. Not sure about other years. I'm currently running a 16/32 but want to go to a 17/32 and give it a try. I'm running #520 chain and the last time I replaced sprockets no one had 17s in 520 available so I went with the 16 instead. The 16/32 is great on our Interstates but it just doesn't work well when I put my 220 pound butt plus gear and take off to the Blue Ridge mountains for a few days.
 
Hello,
today I finally had the opportunity to compete against another xs. This one has a port and polish head, tm34 carburetor like mine and an original exhaust. No chance against mine, not to compare. Starting point was both side by side, 3rd gear, about 70km/h, then full throttle. Mine is blown off, I saw the other one getting smaller and smaller in the rear view mirror.
Yes, the comparison is not quite fair, because I have 100cc more and a shell #1, but the difference is already very big, so I think that I have a very well tuned combination of head, camshaft, carburetor and exhaust and the head plays a big role. I hope to be able to make a comparison with a 750cc bike this year... And to have saved money for a dyno run sometime.

I also have the feeling that the engine wants to breathe more in the upper revs and I should get even bigger air filters.

We swapped bikes and do the test again. My bike will rev in the 4th gear till death. The other bike felt a bit sleepy in 4th gear upper regions and a lot sleepier in the 5th gear. Big difference, like a different bike.
 
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That head is a combination of high CFM volume beginning at mid lift for more power down low to max RPM and higher port velocity for improved efficiency and not knowing how this increased efficiency will impact fuel atomization,there's a good chance that a reduction in main jetting maybe required,just guessing here. You need to make a few WOT runs then immediately shut it down to pull the plugs and check the plug coloration.
This will get you pointed in the right direction for reading plus.
https://www.hotrod.com/articles/spark-plug-reading-101-dont-leave-hp-table/
 
First off a kind hello to the Xs community from Italy

@spungle

Nice bike you have there, but if you don't mind me saying the info about no return valves on the crankcase, d-shaped ports in combination with the recommendation of the use of of a higher lift reasonably short duration Megacycle or web cam profile has been for years on the German forum.

@Jack
Compliments to your nice d ports, don't mind the critics of some people that might not fully comprehend the theory about such (btw very nice looking) d-ports.
I have been using D-ports, where needed, for decades now and with proven track success on Sr/Xt engines (did not find the time for my Xs engines within the last year's due to work) among several other brands (honda, Ktm, Norton, triumph, and among other mod's even DBD34 Goldie's) and makes.
The only thing that remains crucial in doing such work is that the cam should be chosen accordingly to the port properties or better said the port should be shaped according to chosen cam profile spec's (mean flow, maximum increment flow which is not maximum flow and maximum flow lift etc etc).
Kind regards

Christian

Ps: sorry just read it now, spungle, if you don't mind me asking, who welded and how the crank I assume in Germany? Given the fact that the crank and iniin particular the pin is of a higher alloyed
steel it is important to weld it in a certain temperature releasing / inducing mode in order to not brittle out the HAZ.
 
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Hey Christian, thanks:)
My crank was rebuild by an reputated member of the German forum. He rebuilded many xs650 cranks for over a decade, if not many more years. He weld cranks for racing (sidecar) xs650, some of them with over 1000ccm. If there were problems with his welding I would know it. The forum whispers such things normaly. I have no technical background. My way is to read, read and read, try to understand, recheck, and look at the expertise from members. Other than that i have to trust them:) And till now it works like a charme:D

Btw., Last 2 months little time to wrench and final tune my little rocket. Last week I worked the "ported" spigots. The next time I will final tune the carbs. Till know not shure with the mainjet. One size or two size down, I have to figure out now.
 
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Further to Jacks Posts #49 and #50.

For those intending to use high lift cams and reuse existing valve guides.

Megacycle state in their catalogue that if using a cam with a greater lift than their 250-20 cam valve guide modification is needed.

The give a figure of .080” needs to be removed for the higher lift cams.

I was looking at some valve guides today wondering if it would be difficult to do and if there was enough meat in the necked down area of the stock guide.

Removing 2mm from the top leaves very little of the top land left for the valve seal to clip onto. Removing 2mm is problematic for seal fitment.

Fortunately, I had a head with modified valve guides on the bench and was able to take measurements. These guides are 5mm shorter than the stock guides. By removing 5mm from the top of the stock guide enough of the angled section remained to give a nice chamfer on the top edge. I then used a 3mm parting off tool to cut the groove for the seal to grip on.

This was just a trial run on an old guide to see how hard it was to do. The photo shows a modified guide next to a stock guide.
shortned vakve guide.jpg
 
@Signal

Thanks for the info.
I have by now the rude lift cam (planning to do the rocker hardfacing myself) already laying in the shop, but am still waiting on the big valves. As soon as my job and family permits me i will let you guys know how much distance is really needed.

All the best and kind regards

Christian
 
I have the d-port that @Jack mentioned dropping off to Hugh. I found what looks like delamination on the floor and in various other spots in the epoxy...

Anyone have any ideas on what I should do??
 

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I have the d-port that @Jack mentioned dropping off to Hugh. I found what looks like delamination on the floor and in various other spots in the epoxy...

Anyone have any ideas on what I should do??
Saw that you PMd me but somehow I lost those messages just the other day and want to assure you that I had no dealings with applying JB epoxy in those ports. That D port was half-assed and should have never been sold till that port was prepped correctly and epoxy applied professionally to prevent lifting. Did you get the problem resolved? There wasn't enough epoxy applied to the floor ( you want 3 to 4 mm on floor with a roof height of 30 to 31mm) to build up the short turn to form and adjust the radius turn. Also what are you using for manifolds?
 
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Hello Jack.
I actually have Garrett's head.
I reached out to him as I am about to do a D Port to my own following your epic thread. I offered to do the repair as I was eager to see "your work" up close, but alas Garrett discovered that it wasn't done by you at all. The plan is to test the head as is and then prepare the surfaces correctly before reshaping it as necessary. I just finished completing the vacuum box and settling box for my flow bench. The sealant needs to cure for about a week before it pulls suction. Only have the manometer board to make, as well as pick up a few connectors to complete the wiring and I will be testing the bench next weekend. I plan to to simultaneously test one of my stock heads for that baseline as well.
Could be interesting. I am amazed by your ability to get such great results with having the aid of a flow bench during the process. That is a testament to your knowledge of these heads and your abilities. I was planning on posting about this after testing next weekend. Your post made for the perfect opportunity. I will be creating the thread for those interested in following in about 10 days or so. I've been looking forward to doing this for a very long time. I would like to thank Garrett for the giving me the impetus to start the process sooner than later.
It is good to see you back. I am sure I may have some questions.
PS.
I also have his manifolds which I will be port matching as well.
 
I'll be watching this thread, just follow what's written in the D thread as closely as you can or post or Pm me a question. This port when done right
will pull hard down low to the cams max RPM range. It's the ideal street port for the xs small stroke and limited small cam lifts. On the manifolds,
aluminum braze then for best results. Good Luck

What cam is being used will depend on how the short turn radius is profiled. One more thing when those intake ports were milled out the angle
at the spigot was off. Just take a standard head and measure with calibers and use those measurements as a cross-reference before installing
port floor epoxy anchor studs, then adjust their height accordingly
 
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He and I both have a Shell 1
I appreciate the tips and the offer.
I will unquestionably be asking for feedback
 
NP Jack...
I'm at least 10 days out before the port work starts. I will be videoing the flow bench testing as well as flow balls, strings, smoke etc. step by step as I go. I will also be making molds.
Tests are expected to be done at 28" of water.
The Vacuum chamber has 7 high cfm motors and should reach that easily. I have some automotive heads to do as well so it is built beyond the needs of these xs650 heads.
 
Further to Jacks post #35 and #292.
The stock head I am experimenting with had a 6 degree angle on the port floor. With the tools I had the easiest way to rough out the floor was to clamp the head square and tilt the quill.

The smallest diameter cutter I had that was long enough was 18mm and the bottom corner radius is 9mm which looks too big. I think a 10mm cutter 5mm radius would be better.
 
Interesting Signal...
I need to measure the radius on Garrett's D Port; but whatever it is, I am thinking it is too tight.
Finding a lot of dead area in those corners using the smaller flowballs. That is an indication that material should be added.
I will be making those cuts and modeling the port with clay next week looking for the optimum. I have a flowball manual if you would like a copy.
They are cheap and easy to make if you don't have any. They will tell you a great deal about how the air is moving.
One of the advantages of having the bench as you mold the port.
 
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