RH4 To Narley Port Conversion Tubes

worntorn said:

Pete, I am thinking of fitting and testing the sleeves soon, if I get some time.
Unfortunately my wife has been going thru Chemo ( didnt work) and is going for CAR T treatment next. I've been looking after her, not much time for motorcycles this year.

Glen

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Glen,

Sorry to hear about your wife. I wish the both of you the best of luck. I will keep you guys in my prayers
Pete

worntorn said:

Pete, I am thinking of fitting and testing the sleeves soon, if I get some time.
Unfortunately my wife has been going thru Chemo ( didnt work) and is going for CAR T treatment next. I've been looking after her, not much time for motorcycles this year.

Glen

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I'm very sorry to hear about your wife's health issues. You both have my sympathy. I know how much that sort of thing can change your life. CAR-T therapy is an amazing example of how rapidly medical science is progressing. I hope it works well for your wife.

For once, I agree with Acotrel. Caring for our loved ones always takes precedence.

Ken

Hang in there Glen and Mrs. Life can be a challenge sometimes. Sorry to hear that mate. Hopefully she can get well soon. Sending positive thoughts.
Jerry

Positive vibes going your way Glen. Best wishes for you and yours.
Tom

I got the Intake port sleeves put into my 73 RH4 head finally. I will try them out this weekend at the ONO Norton Rally in Barry's Bay.
I will report back. The bike is almost together. A few more twists of the wrenches.

Hit a pretty big snag today. Looks like Sudco has closed their doors in the US, which means there is no Keihin distributor here, and I am struggling to find a couple 2.5 throttle valves. I like these carbs, I have a good jet and needle assortment, but I hope it is enough if I do find these slides.

maaseyracer said:

Hit a pretty big snag today. Looks like Sudco has closed their doors in the US, which mean there is no Keihin distributor here, and I am struggling to find a couple 2.5 throttle valves. I like these carbs, I have a good jet and needle assortment, but I hope it is enough if I do find these slides.

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WOW, Sudco closing is a BFD...
And it is true.

Very Sad news...

maaseyracer said:

Hit a pretty big snag today. Looks like Sudco has closed their doors in the US, which means there is no Keihin distributor here, and I am struggling to find a couple 2.5 throttle valves. I like these carbs, I have a good jet and needle assortment, but I hope it is enough if I do find these slides.

Click to expand...

That is a big snag.

I wonder if anyone has ever tried Lectron carburettors on a Commando ? They appeared in Australia in the 1970s and were successfully used on two strokes. Mikunis are basically two stroke carbs. Witha two stroke,the fuel adjustments usually need tobe much finer. I suggest that with normal carburettors, the internal diameter of the needle jets and the taper on the needles, have a critical effect on performance, when the carbs are on a Commando motor. From memory, the Lectron carbs gave finer adjustment by turning the needles. But I did not know how that functioned. There might have been a flat on the needles.

acotrel said:

I wonder if anyone has ever tried Lectron carburettors on a Commando ? They appeared in Australia in the 1970s and were successfully used on two strokes. Mikunis are basically two stroke carbs. Witha two stroke,the fuel adjustments usually need tobe much finer. I suggest that with normal carburettors, the internal diameter of the needle jets and the taper on the needles, have a critical effect on performance, when the carbs are on a Commando motor. From memory, the Lectron carbs gave finer adjustment by turning the needles. But I did not know how that functioned. There might have been a flat on the needles.

BILLETRON™ PRO Big-Air (300cc-500cc)

Introducing the BILLETRON™ PRO-SERIES Big-Air: A groundbreaking carburetor that redefines two-stroke performance for 300cc-500cc motors. With innovative design and precise engineering, experience unprecedented torque, horsepower, and rideability gains. The PRO SERIES boasts tailored air flow...

www.lectronfuelsystems.com

Click to expand...

Lectrons run well on a triumph, hard to fit on a commando. same issue as the Mikuni vm. I prefer the VM, there is more tunability and resource for less money and you can make a VM do things a flat slide cannot. The TM is a great carb too if you just have to have a flat slide, though fitment is worse on a Commando.

maaseyracer said:

Hit a pretty big snag today. Looks like Sudco has closed their doors in the US, which means there is no Keihin distributor here, and I am struggling to find a couple 2.5 throttle valves. I like these carbs, I have a good jet and needle assortment, but I hope it is enough if I do find these slides.

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That’s a shock.

I’m sure if you shop around you’ll find other suppliers as these carbs are SO popular.

If not, then try these guys. They were the only supplier I found who supplied the correct o ring for the float valve housing in their kits, all others used ‘standard’ looking o rings which were too fat for the application. So, long way of saying, these are good guys:

I suggest one of the things which limits the Commando are carburettors which cannot be tuned fine enough. Fuel injection systems seem to be better when combined with programmable ignition systems. About the third bike I built was a methanol-fuelled T250 Suzuki racer. My experience with that changed the way I tuned my Seeley 850. With two-strokes, the throttle always needs to be fed on in a controlled fashion - My Seeley 850 is like that. It actually accelerates faster than if the jetting was richer in the midrange, and I whacked the throttle open. Some old cars used to have accelerator pumps in their carburettors. It is a different way of thinking. There is one air/fuel ratio and ignition timing which gives maximum power and we work around it. When we whack the throttle open, we lose vacuum and there is less depression on the needle jets. Leaner needles help if we are not heavy-handed.

acotrel said:

I suggest one of the things which limits the Commando are carburettors which cannot be tuned fine enough. Fuel injection systems seem to be better when combined with programmable ignition systems. About the third bike I built was a methanol-fuelled T250 Suzuki racer. My experience with that changed the way I tuned my Seeley 850. With two-strokes, the throttle always needs to be fed on in a controlled fashion - My Seeley 850 is like that. It actually accelerates faster than if the jetting was richer in the midrange, and I whacked the throttle open. Some old cars used to have accelerator pumps in their carburettors. It is a different way of thinking. There is one air/fuel ratio and ignition timing which gives maximum power and we work around it. When we whack the throttle open, we lose vacuum and there is less depression on the needle jets. Leaner needles help if we are not heavy-handed.

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Accelerator pumps still work. Put FCRs on your 850 and see how it goes. You'd have to ride it though and not just talk about it on the couch reliving glory days.

Schwany said:

Accelerator pumps still work. Put FCRs on your 850 and see how it goes. You'd have to ride it though and not just talk about it on the couch reliving glory days.

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Reading these posts are giving me the urge to race again. I dread going near Winton Raceway. The car idiots really annoy me, but the other option is stupid and dangerous. I still need to get my glasses fixed now that I have full colour vision. Before Mick Ronke died, there was motorcycle practice at Winton every Friday. The car guys own the circuit and they were too piss-weak to front Mick. The bikes used to get a fair go. Now it is a waste of time going there. One of my brother's mates now lives in our town and he has road raced. It is better if the helper also gets to ride the bike. When Allan Greening was alive we both raced the bike. I first met him when I was 18, and I had never seen him so happy.We just worked together and shared the rides - it is a good way to race. Doing it on your own is much more difficult. I have done that, and I would not do it these days.

All the work reported on the forum recently on improving performance of RH4 heads is exciting and makes for some very interesting reading. I applaud all the contributors involved in the various aspects of this undertaking.

Because I have a stock ‘74 CDO with an RH10 head, I have no context for the recited performance improvements, e.g., improved low/mid-range torque, more power through the higher rpm range, better top end, etc, reported after retrofitting an RH4 head with an intake port sleeve variant. I’m not sure but believe that such performance enhancements are intended to make an RH4 headed bike equivalent to an RH10 headed analog, all other things being equal. Or maybe I’ve got it wrong and the goal is to make an RH4 head exceed the performance of an RH10 head. Or maybe it’s just to improve the performance of an RH4 head, but with no specific performance goal in mind.

Regardless, all the insert approaches (machined, printed aluminum, etc) are providing qualitative performance improvements (seat of the pants dyno, need for re-jetting, etc) which makes me all the more curious to know quantitatively (flowbench, dyno) how much performance actually improved (1?, 3?, 5? HP). I personally think it might be quite challenging to decode 1-3 HP changes via seat-of-the-pants experience with 2 good running bikes. As the various approaches continue, they might even exceed the airflow or HP achieved via a stock RH10 head? But how will we know when we’ve hit that milestone?

I think it would be a really cool aspect of the entire undertaking if it could all be tied together with quantitative information, i.e., see and understand all the pieces of the puzzle, where each individual piece is congruent with all other pieces. I suspect in such an undertaking that the probability of being surprised by some aspect of it - surprised good or surprised bad, but nevertheless surprised - would likely occur, which is the rewarding part of iterative experimentation and learning.

It’s easy for me to suggest quantifying the subject information, but it’s a serious, time consuming, and spendy undertaking to generate airflow and dyno results for each variant. But as progress continues here, at some point performance information has to be quantified if improvements are to continue. One much less expensive approach might be to use the “real” road like Worntorn does with dyno hill, but we don’t all live in the mountains. Perhaps some onboard electronic data acquisition device could identify performance differences?

With a motorcycle, everything works together to make a package, which affects performance. In road racing, what suits a amall circuit often does not suit a large circuit, and lap times do not ensure success. In races we race around other competitors, and the lines which give the smallest lap times often cannot be used. A simple thing such as inlet port size can affect versatility. If we could ride, always using high revs and full throttle, large ports might be better. Experience on the IOM might have determined the port size which waa used on the earlier Commandos.
I still have nightmares about racing my 500cc Triton. When it entered a corner, the rider was always fully committed. It always had to be kept revving high. If somebody got in front, and there was no way around them , it was game over.

WZ507 said:

All the work reported on the forum recently on improving performance of RH4 heads is exciting and makes for some very interesting reading. I applaud all the contributors involved in the various aspects of this undertaking.

Because I have a stock ‘74 CDO with an RH10 head, I have no context for the recited performance improvements, e.g., improved low/mid-range torque, more power through the higher rpm range, better top end, etc, reported after retrofitting an RH4 head with an intake port sleeve variant. I’m not sure but believe that such performance enhancements are intended to make an RH4 headed bike equivalent to an RH10 headed analog, all other things being equal. Or maybe I’ve got it wrong and the goal is to make an RH4 head exceed the performance of an RH10 head. Or maybe it’s just to improve the performance of an RH4 head, but with no specific performance goal in mind.

Regardless, all the insert approaches (machined, printed aluminum, etc) are providing qualitative performance improvements (seat of the pants dyno, need for re-jetting, etc) which makes me all the more curious to know quantitatively (flowbench, dyno) how much performance actually improved (1?, 3?, 5? HP). I personally think it might be quite challenging to decode 1-3 HP changes via seat-of-the-pants experience with 2 good running bikes. As the various approaches continue, they might even exceed the airflow or HP achieved via a stock RH10 head? But how will we know when we’ve hit that milestone?

I think it would be a really cool aspect of the entire undertaking if it could all be tied together with quantitative information, i.e., see and understand all the pieces of the puzzle, where each individual piece is congruent with all other pieces. I suspect in such an undertaking that the probability of being surprised by some aspect of it - surprised good or surprised bad, but nevertheless surprised - would likely occur, which is the rewarding part of iterative experimentation and learning.

It’s easy for me to suggest quantifying the subject information, but it’s a serious, time consuming, and spendy undertaking to generate airflow and dyno results for each variant. But as progress continues here, at some point performance information has to be quantified if improvements are to continue. One much less expensive approach might be to use the “real” road like Worntorn does with dyno hill, but we don’t all live in the mountains. Perhaps some onboard electronic data acquisition device could identify performance differences?

Click to expand...

A couple things here. As I understand it the JS sleeves originally were designed to give the RH4 a better powerband similar to the power band of an RH10 (JS may want to weigh in as I do not want to speak for him). I have run my engine with a stock RH4, Rebuilt RH4, and RH4 converted to RH 10 spec, and now these Narley conversion sleeves.

Before I go any further with comparisons to other products I want to state the obvious and say that the Full Auto head is a superior product to anything I have designed or have made, it is a beautiful casting, with a great port shape, and I have come ridiculously close to buying one including putting a deposit down on one. Everything I am doing is based on a stock 70s casting head and the limitations of that head. While I may compare port shapes to the FA or other products, I am not comparing the totally of the product. The shape, area, and usage is not the same and it is not even the same as the JS Narley port. It is the best I can squeeze into the confines of the RH4 head.

I compared the stock, RH4, RH10, FA, and the JS Narley port drawings, and I focused on cross sectional areas across the whole port, but especially in the transitions from and to the intake entrance, 45mm from the valve, 30mm from the valve, and 15mm from the valve. I am not wanting to share my cross sectional numbers just yet as I am still iterating them, but they are larger than the FA port and smaller than the Narley port. Getting to Narley port numbers would require cutting into the cylinder head.

My goal is to tap into the potential of a once written off RH4 head while retaining reliability and street manners all through a simple drop int device. The big issue with the RH4 head is that the port velocity is low from a port that was made too big at the factory and the powerband starts to come on too high in the rev range. The RH10 sleeves brings the powerband much lower and the Narley conversion sleeve does not change that much, but intensifies that power band by increase the port velocity.

I do not have a flow bench or dyno, I would like to flow test these in the future. I have plenty of hills to "dyno" on, but all comparisons are by the seat of the pants. I have a phone data logger, but it is a pain to use on a motorcycle and requires things that I would be guessling like a coefficient of drag. I can tell you the difference was noticeable before I ever got to the hill with the JS sleeves and these sleeves. You feel it right away.

As far as horsepower goes, who knows, it depends on where and over what duration that power comes in you might not be able to feel a 10% gain if it develops over a long period. These sleeves develop torque fairly low and the gains feel like they are carrying on up through the rev range.

acotrel said:

I wonder if anyone has ever tried Lectron carburettors on a Commando ? They appeared in Australia in the 1970s and were successfully used on two strokes. Mikunis are basically two stroke carbs. Witha two stroke,the fuel adjustments usually need tobe much finer. I suggest that with normal carburettors, the internal diameter of the needle jets and the taper on the needles, have a critical effect on performance, when the carbs are on a Commando motor. From memory, the Lectron carbs gave finer adjustment by turning the needles. But I did not know how that functioned. There might have been a flat on the needles.

BILLETRON™ PRO Big-Air (300cc-500cc)

Introducing the BILLETRON™ PRO-SERIES Big-Air: A groundbreaking carburetor that redefines two-stroke performance for 300cc-500cc motors. With innovative design and precise engineering, experience unprecedented torque, horsepower, and rideability gains. The PRO SERIES boasts tailored air flow...

www.lectronfuelsystems.com

Click to expand...

I had a 40mm lectron on mine back in the 80's. It worked great until a rubber part that held the needle failed and I couldn't find one (no internet). Sold it and put the Amals back on. I liked it though.
Jaydee

It is great to see that we as group who own these 50 year old Commandos are at it, working on improvements to the classic design.