RH4 To Narley Port Conversion Tubes

Fast Eddie · Jun 28, 2024

maaseyracer said:
When I started this post, I pointed this out explicitly, anything I make is ~~half~~ quarter assed compared to a modern design and casting . I am merely trying to maximize value and trying redeem aspects of the RH4 head (not sure anyone can do about the guides).

While I know for a fact that the intake ports maximize value, the exhaust port seatings are getting closer...

I am not doing anything new, what I am doing has been done for decades on the 351cleveland, they call them, "351 port plates" do a google image search you will see what I mean. I worked for a shop years ago that had a dyno and built historics engines and the owner had a reputation for building 351c engines. we did a lot of experimentation with these especially on street builds or where there was need to keep the engine looking stock, but still make good power. Like all things engine variables matter, and tuning matters even more.

PS These came in the mail today, I should know shortly more about these:

Whether or not these things yield results is, of course, still to be ascertained.

But you don’t know unless you try!

That fact you are pursuing these ideas in this way is fantastic, and to be applauded.

Sell me a pair to try and you shall be applauded even more !!

acotrel · Jun 28, 2024

I have found that with every change I have made, other things must be adjusted to realise any value from the change. If you improve torque somewhere in the usuable rev range, a change of gearing is often needed to use the improvement effectively. With my 850 motor, I simply built it from experience from other bikes I'd had - then adjusted the gearing, jetting and handling. If I had not known anything, I would have just started with an unmodified motor and developed it. But I would have made the mistake of enlarging the inlet ports , and I would probably have put the power band in the wrong place.

acotrel · Jun 28, 2024

One thing which is very deceptive is gearing. If you have a wide ratio gearbox,it is easy to believe the bike is going as fast as it can. When I tried to race using a normal 4 speed Norton box, the bike was useless everywhere. The problem is, to get the gearing correct, you need to know the race circuit on which you use the bike, very well. A beginner does not usually know where they are, anywhere on a race circuit. For a road bike, any gearbox is usually OK.

Schwany · Jun 28, 2024

maaseyracer said:
When I started this post, I pointed this out explicitly, anything I make is ~~half~~ quarter assed compared to a modern design and casting . I am merely trying to maximize value and trying redeem aspects of the RH4 head (not sure anyone can do about the guides).

While I know for a fact that the intake ports maximize value, the exhaust port seatings are getting closer...

I am not doing anything new, what I am doing has been done for decades on the 351cleveland, they call them, "351 port plates" do a google image search you will see what I mean. I worked for a shop years ago that had a dyno and built historics engines and the owner had a reputation for building 351c engines. we did a lot of experimentation with these especially on street builds or where there was need to keep the engine looking stock, but still make good power. Like all things engine variables matter, and tuning matters even more.

PS These came in the mail today, I should know shortly more about these:

Didn't mean any disrespect. I think what you are doing is better than a half assed project.

My only point was if I were to install something like the inserts, I know I would put more work into smoothing the transitions on all the edges of the inserts inside the ports to get the most out of the modification. Others would probably do little else than glue them in and expect improvement.

My 350 Gen 1 Cheby engine has aftermarket heads on it with D-port exhaust ports, roller cam, and other things. It sounds awesome, but a Prius is probably faster.

jseng1 · Jun 28, 2024

Here's a pic of the 351 port plate.

Getting the tip near the seat to press down on the Norton port to avoid a gap for a smooth transition is the challange. Massyracer has his work cut out for him but its not impossible.

acotrel · Jun 28, 2024

Schwany said:
Didn't mean any disrespect. I think what you are doing is better than a half assed project.

My only point was if I were to install something like the inserts, I know I would put more work into smoothing the transitions on all the edges of the inserts inside the ports to get the most out of the modification. Others would probably do little else than glue them in and expect improvement.

My 350 Gen 1 Cheby engine has aftermarket heads on it with D-port exhaust ports, roller cam, and other things. It sounds awesome, but a Prius is probably faster.

I think similarly. What happens when both valves are open around TDC is probably not low velocity flow, across the top of the piston and into the exhaust. At high velocity, it might be easier for imperfect transitions to create bumps in the flow which could slow the rate of mass transfer. Because of the valves, the flow is probably more towards the top of the ports. The inserts might reduce any stalling effect due to resonance - better direction of the pulse ?

maaseyracer · Jun 28, 2024

Schwany said:
Didn't mean any disrespect. I think what you are doing is better than a half assed project.

My only point was if I were to install something like the inserts, I know I would put more work into smoothing the transitions on all the edges of the inserts inside the ports to get the most out of the modification. Others would probably do little else than glue them in and expect improvement.

My 350 Gen 1 Cheby engine has aftermarket heads on it with D-port exhaust ports, roller cam, and other things. It sounds awesome, but a Prius is probably faster.

No disrespect taken, and I am doing this purely for the sake of having fun and learning something new.

I had a lightbulb moment last night and I used my phone to 3D scan the head and the exhaust port. I did a quick scan using an year or two old iPhone, I am sure there are better LiDAR scanners in phone now, and I have seen some very cool work in this area on cars. If I had taken a bit more time I think I could have gotten a more visually appealing scan. However, I was able to verify the sizing to be surprisingly accurate. This helped me get tighter in the port and fix my floor transition issue. I sent a new design out to be printed this morning, and I am excited to see how close I get.

I installed the MK3 style exhausting seating at lunch time and took the bike out, and promptly broke my cheesy nylon throttle tube. Limped home through town using the throttle wheel on the side of the carbs. I had a space 305 honda throttle lying around, and after a few minutes of lining it up I was able to get back out there. First thing I noticed was on both outings today is that the bike is back to running lean again. Especially just off idle, it is very noticable and you can hear it, 0 to 1/8 throttle is probably the most noticeable. The lean issue is completely resolved by quarter throttle. Above quarter is good, and above half seems lean to me. Deceleration is popping much more than usual as well. I did two 2nd gear pulls and somewhere above 5000 or 6000 rpm there is a noticeable gain, hard to know where the veglia tach is bouncing a lot over 5000 rpm. The gain is nowhere near as dramatic as the intake tubes where you feel it everywhere. Honestly I am surprised I felt anything at all.

I'll do a more involved testing tomorrow, but I am very happy how this is progressing.

Schwany · Jun 28, 2024

maaseyracer said:
No disrespect taken, and I am doing this purely for the sake of having fun and learning something new.

I had a lightbulb moment last night and I used my phone to 3D scan the head and the exhaust port. I did a quick scan using an year or two old iPhone, I am sure there are better LiDAR scanners in phone now, and I have seen some very cool work in this area on cars. If I had taken a bit more time I think I could have gotten a more visually appealing scan. However, I was able to verify the sizing to be surprisingly accurate. This helped me get tighter in the port and fix my floor transition issue. I sent a new design out to be printed this morning, and I am excited to see how close I get.

I installed the MK3 style exhausting seating at lunch time and took the bike out, and promptly broke my cheesy nylon throttle tube. Limped home through town using the throttle wheel on the side of the carbs. I had a space 305 honda throttle lying around, and after a few minutes of lining it up I was able to get back out there. First thing I noticed was on both outings today is that the bike is back to running lean again. Especially just off idle, it is very noticable and you can hear it, 0 to 1/8 throttle is probably the most noticeable. The lean issue is completely resolved by quarter throttle. Above quarter is good, and above half seems lean to me. Deceleration is popping much more than usual as well. I did two 2nd gear pulls and somewhere above 5000 or 6000 rpm there is a noticeable gain, hard to know where the veglia tach is bouncing a lot over 5000 rpm. The gain is nowhere near as dramatic as the intake tubes where you feel it everywhere. Honestly I am surprised I felt anything at all.

I'll do a more involved testing tomorrow, but I am very happy how this is progressing.

Next iteration looks way better than I imagined. Nice.

So both the intake port sleeves and exhaust port whatever they are going to be called were in there for this test session?

maaseyracer · Jun 28, 2024

Schwany said:
Next iteration looks way better than I imagined. Nice.

So both the intake port sleeves and exhaust port whatever they are going to be called were in there for this test session?

Correct.

Jetting is off with the addition of the exhaust seating (calling it what the parts manual calls it for a MK3), confirmed just with my AFR gauge. What is interesting, is while this produces top end power, jetting from idle on up is effected.

worntorn · Jun 28, 2024

Schwany said:
Your results are about what I would expect using imagineered anti reversion slugs for your torque torture test. Only thing that would help with acceleration is using a lower gear at the base of that climb. lol

I suppose I could have spent some time making them pretty but I don't think it would change the result. They actually fit the pipe very well. I guess the main effect is from the little vertical wall.

What might change things is moving from the header pipe, where I installed the tapered slugs, into the exhaust port as these do.

Schwany · Jun 29, 2024

maaseyracer said:
Correct.

Jetting is off with the addition of the exhaust seating (calling it what the parts manual calls it for a MK3), confirmed just with my AFR gauge. What is interesting, is while this produces top end power, jetting from idle on up is effected.

You know what to do, right?

If you actually end up selling them, you might have to provide a mini-tuning manual.

Schwany · Jun 29, 2024

worntorn said:
I suppose I could have spent some time making them pretty but I don't think it would change the result. They actually fit the pipe very well. I guess the main effect is from the little vertical wall.

What might change things is moving from the header pipe, where I installed the tapered slugs, into the exhaust port as these do.

The little wall doesn't seem to work as witnessed by both you and Nigel. There is nothing in this for my use, but If I wanted to chase my tail some playing around with the exhaust mod, I'd let maaseyracer do all the heavy lifting first then see if I could duplicate it somehow.

maaseyracer · Jul 5, 2024

I made two more versions based on the 3D scan. This one does not extend back as far and uses the Norton port cuving coming off the valve seat. The fit on it, is good, going to take a few days before I can test this iteration waiting on a new clutch cable and some jets.

maaseyracer · Aug 27, 2024

A quick update:

I am going to keep drawing and developing these as best as I can to further find more in these old bikes. It is a great hobby for me. However, I really need to keep this a hobby. I have a more than full time job, a young family, and really do not have the time to fulfill orders. I have passed that on Jim Schmidt, who inadvertently started me down this path. I think the products are better with his eye for detail on them, than mine. I take no license or commision on these, I want to make sure that everyone has access to these parts at the best price they can be produced for, and I want to keep this a hobby to make sure I have fun with it. I may in the future make something I take royalty on, but for now I need to put priority elsewhere.

3D printed Exhaust washers are up on Jim's site: https://jsmotorsport.com/product/raised-exhaust-port-floor-shoes/

I am going to be testing the latest version MK3 exhaust fittings in the next day or two, the fit is good so I suspect they will be good and up shortly.

Intake tubes for 32mm ports are hopefulling going up soon the shape on these is incredibly important for them to work right, 3D printing is nowhere near as precise as CNC, but the shape of these floors makes CNC cost prohibitive. 3D print may be the best option and it may require some hand filing, dremel work, or die grinder shaping to fit, but I am looking into if that can be avoided.

I personally think these Narley sleeves are the best performance upgrade for the buck you can buy for a 32mm port Norton and have made my already strong 850 Mk3 even stronger

I have a design for 29/30mm ports coming as well, however they will require 32mm intake manifolds or the manifolds Jim sells. I should have some drawings up on these in the coming days.

maaseyracer · Aug 28, 2024

Forgot to post these last night. Here is a screen shot of the 29/30mm Port sleeve. The exit corners will get cleaned up once I see how they fit in the head. Initial test show 510 loctie does a great job holding them in place and the ring helps locate the manifolds and secures them from going anywhere we dont want them to go.

The MK3 Exhaust fitting is sorted and I have a printed pair in stainless that I installed today. Was interesting to look over the ones I took out. I have not been easy on the bike the last several rides as I have been dialing in a tune, and starting to take the bike out further and harder with the tune. These exhaust fittings held up nicely.

worntorn · Aug 28, 2024

Nice!

Glen

Schwany · Aug 28, 2024

Here are some useless old guy with a dremel thoughts I have regarding the 29/30 portsleeve:

If'n it were me I'd start with thicker 30mm intake manifolds, cut a ring in the head end of the manifolds for your port sleeve ring, and blend the carburetor end of the manifolds to match whatever carburetor bore is being used. It would be like a smooth venturi intake if using 32mm or larger carburetors. Anyway, there wouldn't be a step at the head end of the intake manifold caused by the port sleeve ring. Granted it would be some tedious blending work, but it could pay off, if going fast was the object. If making some more torque for a street bike by using smaller ports with a raised floor, it might not be worth the blending effort.

I could be misunderstanding how the design actually works though. It would not be the first time.

maaseyracer · Aug 28, 2024

Schwany said:
Here are some useless old guy with a dremel thoughts I have regarding the 29/30 portsleeve:

If'n it were me I'd start with thicker 30mm intake manifolds, cut a ring in the head end of the manifolds for your port sleeve ring, and blend the carburetor end of the manifolds to match whatever carburetor bore is being used. It would be like a smooth venturi intake if using 32mm or larger carburetors. Anyway, there wouldn't be a step at the head end of the intake manifold caused by the port sleeve ring. Granted it would be some tedious blending work, but it could pay off, if going fast was the object. If making some more torque for a street bike by using smaller ports with a raised floor, it might not be worth the blending effort.

I could be misunderstanding how the design actually works though. It would not be the first time.

You probably do not want to bore into a manifold to accommodate these. The ring tapered on the entrance and fits/blends better than 32mm manifolds fit and blend into a 32mm port. Opening the manifold bolt holes a 1/32 to 1/16 will get the manifolds to center on the ring to the port and it makes for a nice transition. With straight manifold I could probably make a longer ring for a smoother taper. I only have curved manifolds to test on which I know is not ideal for everyone, and limits my testing ability. Most importantly for my piece of mind is that the ring keeps the aluminum piece locked from going through the valve.

Also here is a better rendered shot of the exhaust side.

acotrel · Aug 28, 2024

maaseyracer said:
After a ton of research, trial, error, failure, frustration, and figuring it out I have finally got to the functional prototyping stage of a conversion tube that helps an RH4 head get close to the Narley Ports documented by Jim Schmidt.

I have spent a good amount of time reading and modeling Jim's XR750 to Norton port documentation and communicating with Jim to get this to where it is. The idea is continuation on the idea from Jim Schmidts work on the RH10 Conversion tubes. I elected to get first round of prototypes 3D printed in aluminum and these are now in their second revision and are being run presently in my MK3 Norton. The goal is to increase the velocity into the port, develop a bit more torque down low and carry on up high as well.

With a third revision underway, I am feeling much better about sharing what I have been up to.

Sending files out via email then receiving these in the mail a week later was a trip:

Removal of the old RH10 conversion tubes was simple. A bit of heat from a torch and a tig welding glove had them out in no time. I cleaned the port with acetone, let it dry used Loctite 510 on the new sleeve and installed.

This is all new territory for me and I am still shocked that this actually fit let alone worked as well as it does. Crazy to think how much time and thought goes into something like this. There is a lot to unpack about how it runs after install, idle is quieter and I was able to reduce my idle running a JS2 cam (which like a high idle) down to around 1100 to 1200 rpm from 1400-ish. Starting is easier and time to settle into a running idle is faster. However, when you get on the throttle is when you start to notice things. I immediately noticed a good chunk of low end and midrange and when the cam comes on it is properly fast, it pulls beautifully to 7500 rpm (probably beyond as well). Tons of torque, tons of pull, finding

I am still refining these and plan another revision to get these things to be a closer fit there is still some playing I am doing. A lot of attention has been paid to the cross sectional area and I am working on a slightly more refined fit and dealing with 3D printing specific issues in the next round of prototyping. Curious to hear feedback, this has been a ton of fun to work on and I have already started a couple more Norton projects as well.

That looks like the ports in my 850 head which taper from 34mm to 30mm in the first 12mm.. The port shape changes the requirement for the taper on the needles. The port's diameter can change the revs at which the port is most effective. So it needs to suit the gearing for the circuit. If you have quick taper needles and use more throttle too quickly, you can end up with less torque.

Schwany · Aug 29, 2024

maaseyracer said:
You probably do not want to bore into a manifold to accommodate these. The ring tapered on the entrance and fits/blends better than 32mm manifolds fit and blend into a 32mm port. Opening the manifold bolt holes a 1/32 to 1/16 will get the manifolds to center on the ring to the port and it makes for a nice transition. With straight manifold I could probably make a longer ring for a smoother taper. I only have curved manifolds to test on which I know is not ideal for everyone, and limits my testing ability. Most importantly for my piece of mind is that the ring keeps the aluminum piece locked from going through the valve.

I forgot about how close those bolts were to the sides of the intake manifolds. Doh! What was I thinking?

Tapering the ring would solve all the BS I was talking about. I knew I must have misunderstood the design. You know what you are doing. I'll go back to the corner of the room now.

RH4 To Narley Port Conversion Tubes

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