Norton intake ports compared to Harley XR 750 (2013)

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It might be impractical to extract the whole port model in one piece if the guide is not removable. I use a dummy guide with a sliding fit into the head with a valve. Lightly lubricate all surfaces, place the Blu-Sil and let set. I then remove the dummy guide and valve and then slowly and firmly push the Blu-Sil out through the valve throat.

An alternative is to skip the valve and use only the dummy guide. Fill the valve port as well as the combustion chamber. Once the Blu-Sil is set, peel from the combustion chamber surfaces and then push the remainder out from the port through the valve throat.

You will find the model enlightening
 
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Check this out

https://www.fordmuscle.com/archives/200 ... kingMolds/

I went this route and it worked great.

Lube the port with silicone spray before making the mold. You can leave the guide in but make a cut with an exacto knife from the combustion chamber to the guide. This way you can get the mold out without tearing it up when pulling it out toward the manifold end where it doesn't want to go. Then you just plain have to fight the mold out best as you can. Pushing and pulling and using some French adjectives seems to help.
 

WZ507

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Another silicone option for port casting is Dow Corning Silastic S or the equivalent product Xiameter RTV-4250-S. This is a very tough high elongating Pt catalyzed silicone RTV. In the picture below, the entire head casting was extracted via the combustion chamber, and the single port was pulled back up the port. Extracting up the port, i.e., going "against the grain" of the guide as it were, exerts a tremendous force on the silicone, yet as you can see there is just one small tear at the guide where a thin section of the casting material tore to get free of the guide.

I concur with jseng1, that you really have to have your tough-guy persona and some longshoreman vernacular ready when it comes time to extract the casting, as you literally have to yank your guts out to get the casting out. An extra pair of hands can be invaluable, and a long stub extending far out of the port allows you to get a better grip on the situation.

 
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This particular head had oversize guides, an old std guide slides in and out nicely. I can imagine it may not look the way I think it does.

I've raised the port roof either side the guide by 6mm, if I welded in the valve spring seat area I could probably get it another 4-5mm but that would then need machining and it may not be necessary to get what I want.
 
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mark parker said:
This particular head had oversize guides, an old std guide slides in and out nicely. I can imagine it may not look the way I think it does.

I've raised the port roof either side the guide by 6mm, if I welded in the valve spring seat area I could probably get it another 4-5mm but that would then need machining and it may not be necessary to get what I want.
Mark
Some performance description follow up would be appreciated when the time is right.

The "Narley" head currently being ported (close) to XR 750 specs is at 42x28mm at the guide. Thats a little narrower than the HD port but should do the job. Better to stay small than regret going too big at first. The Narley head was bored to accept thick walled intake tubes so porting could be done over with enough material to start with. Loads of work (need help from Ken at Full Auto)

See Triumph "Harumph" head being hogged out for the XR 750 ports below. Turned out to be a very fast racer - cleaned up in its class and beat some modern bikes as well.

 
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A thought. The wideness at the guide must be there to make it flow more air, it's just a matter of why. I doubt it is just to compensate for the obstruction of the guide and stem.

It may be to turn the air stream into the valve. The design limitation with the A65 head, I have read, is that the air isn't turned and brought down to make full use of the valve diameter, air goes straight through the top half of the valve without making much use of the lower side. What if the flow being directed in the wide sections is actually forcing the air down to use the full diameter.

If this were the case it might be better to close the port down somewhere else (like raising the floor) to get extra air speed if needed.

I think I'll try getting the extra width and when I get a flow rig built see what the difference actually is, easy to fill and check the difference.
 
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Have the width out to 45mm and patching some holes where it went through. The BSA valve angle seems to be 55degree, anyone know what the XR is?
 
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mark parker said:
A thought. The wideness at the guide must be there to make it flow more air, it's just a matter of why. I doubt it is just to compensate for the obstruction of the guide and stem.

It may be to turn the air stream into the valve. The design limitation with the A65 head, I have read, is that the air isn't turned and brought down to make full use of the valve diameter, air goes straight through the top half of the valve without making much use of the lower side. What if the flow being directed in the wide sections is actually forcing the air down to use the full diameter.

If this were the case it might be better to close the port down somewhere else (like raising the floor) to get extra air speed if needed.

I think I'll try getting the extra width and when I get a flow rig built see what the difference actually is, easy to fill and check the difference.
When you get the "Narley Port" CD I sent you you will see that the port floor is elevated a lot compared to a Norton port. The port stays shallow from top to bottom and is raised on the sides of the guide to broaden the port radius so the air velocity stays high without being slowed down by turbulence at the curve (avoiding the problem you mention above with the BSA port). The port does have to be wider at the guide to get around it. Just looking at the image below of a Nascar port shows whats going on. As you say above "the flow being directed in the wide sections is actually forcing the air down to use the full diameter [of the valve]. The floor is raised to the max and a gradual curve brings the fuel/air charge straight down on to the complete circumference of the valve head/seat area when it opens.

I wouldn't go any bigger till you try them out. You can always go bigger but going smaller is a problem.

 

Nater_Potater

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To paraphrase:
mark parker said:
A thought. The wideness at the guide must be there to make it flow more air, it's just a matter of why. I doubt it is just to compensate for the obstruction of the guide and stem. It may be to turn the air stream into the valve.
You hit it on the head with your last statement. Air (and pretty much all fluids) doesn't like to deviate from a straight line. Just ask Newton. This is what limited the early centrifugal compressor jet engines, in the fact that the air had to make a ninety-degree bend from the compressor's outlet to the burn cans. They went as far as putting "cascade vanes" in the elbow in attempts to help the air around the corner.

It was this limitation that really drove development of the axial compressor.

As you envision a port from the side, the difference in length between the floor vs. the roof is what upsets the smooth flow. Air along the floor wants to continue straight, creating turbulence in the bowl above the valve. So, essentially, what we attempt to do is "squash" the port in the middle of the bend, thus keeping its cross-section close to what we started with at the inlet manifold, while bringing the port floor and roof closer to the same length. In doing so, the flow can more easily go around this bend. 'Sure beats trying to glue cascade vanes into the ports... :wink:

Nathan
 
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Nater Potater - thanks for your words about "squashing" the port at the bend to bring the floor and roof closer together to make them closer to being the same length.

Mark - Don't just go for wide ports or larger ports. Raising the floor is of paramount importance and that consideration should come first. The measurements I show in the first post in the thread were not intended to be used as a porting guide. There are too many photos and drawings to post or email so all the details along with the all important side view drawings of 3 levels of performance, photos etc must go on a CD (as is being sent to you). I don't recommend anyone attempt any porting until you have the full "Narley port" CD and all the necessary info so you can pick and choose. There are notes of suggested levels of performance with the 3rd level intended only for the most radically tunes race engines (or large displacement motors).
 
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My motor is 883cc. 79.5 X 89 at the moment it gives 80HP on the data logger at 6,370rpm, if it maxed out around 7,000 or 7,300 it would be good. I'll try keeping the port volume the same as now, then if it flows more it has to have more gas speed and maybe the bottom end and midrange will still be good.



I put silicon rubber in the port but insufficient catalyst, so only got a cast of the bowl area from when I added extra catalyst. It's really cool how it shows the shape, and Ive adjusted that so will try another cast tomorrow.

This head I'm messing with is just to see what fits. I'm finding out where it needs metal added which so far is probably easy enough to weld most places.

If BSA had not cut the valve spring seats so deep the casting would have had an extra 4mm which would save some welding.

CD will probably get here next week so looking forward to that.
 
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A cast:




Bowl area is probably a bit big. But I'll try making something that measures flow before I adjust it any more.
 

Fast Eddie

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mark parker said:
My motor is 883cc. 79.5 X 89 at the moment it gives 80HP on the data logger at 6,370rpm, if it maxed out around 7,000 or 7,300 it would be good. I'll try keeping the port volume the same as now, then if it flows more it has to have more gas speed and maybe the bottom end and midrange will still be good.



I put silicon rubber in the port but insufficient catalyst, so only got a cast of the bowl area from when I added extra catalyst. It's really cool how it shows the shape, and Ive adjusted that so will try another cast tomorrow.

This head I'm messing with is just to see what fits. I'm finding out where it needs metal added which so far is probably easy enough to weld most places.

If BSA had not cut the valve spring seats so deep the casting would have had an extra 4mm which would save some welding.

CD will probably get here next week so looking forward to that.
Interesting looking BSA there Mark. I'm not a BSA expert per se, but I think I see a few non standard parts there...

Please post more pics and tell us more about it, if you have to do this in the BSA section to keep all (ok, most of) the whiners happy then please at least tell us you've done so on this thread.
 
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On the BSA section Eddie. It does have a Norton crank. New port volume is exactly the same as the open round port, so I imagine the midrange power should be still good if I use the new port shape on the bike.
 
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mark parker said:
A cast:




Bowl area is probably a bit big. But I'll try making something that measures flow before I adjust it any more.
Move the widest area of the port forward where it goes around the guide. The bowl will be out of round - wider at the sides and narrower front to back. Then blend to round just before the valve seat. You'll see it in the cross section drawings I sent with the "Narley port" CD. Wait till you get the CD before reshaping any more.
 
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Set up a sort of flow rig, I have an old cyl bolted to my bench so the cyls go through. A vacuum cleaner is set up on the bore I'm testing. I have an air flow meter set in a big plastic box that sits over the cyl and head, it all seals well and reads speed and volume off a spinning prop that air going into the box must pass. It gives a stable read out and responds to valve lift and also to no valve lift where no air enters the box at all.

The new port shape gets a higher flow reading to a port I know flows 158CFM, but not by much, it would work out at 164CFM if the vacuum in the cyl was the same. The thing is I've not yet set up apparatus to read and regulate that vacuum. It may be that unless they are at the same vacuum exactly the readings may be skewed, because a worse flowing port could raise the vacuum in the cyl the same way as less valve lift, making the readings closer than reality. I may also set up two vacuum cleaners to get the air going through at higher speed.

Hopefully when I get it setup better it will work well enough to get readings that can match those of the port I have flow figures on, and use that as a calibration.
 
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Make yourself a simple manometer out of clear plastic tube.

http://www.komar.org/faq/manometer/manometer.jpg

Do a google image search for "home made manometer" to get some ideas.

You may want to figure out some way of throttling or waste gating the vacuum so you can maintain a constant vacuum for the various lifts. This should render data that will be more easily compared to other port flow data. I have used a shop vacuum as it has a bit more power.

Good stuff!
 

WZ507

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There are tomes of information on building DIY flow benches, operating them, calibrating them, interfacing with PCs etc, so have a peak at the links below. These benches may range from inexpensive devices driven by shop vacs to those employing much more powerful and sophisticated depression sources.

https://www.google.com/search?sourceid= ... 4Sbom2MRao

http://www.musclecardiy.com/cylinder-he ... ds-part-3/

http://www.diyporting.com/flowbench.html

http://performancetrends.com/ez_flow_system.htm

http://www.dtec.net.au/Tech%20Articles/ ... Design.pdf

As an aside, if a person undertakes construction of a flow bench, the cost can go up pretty quickly even for a simple bench, which leads me to recall that a friend has a new-in-the-box Superflow 110 Flow bench that he is interested in parting with at a very reasonable price. This is a small bench but is more than is needed for any small displacement engines like we discuss here.
 
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