Fast Eddie
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Hmmmm... then how were you able to ascertain that the text is uninformative without reading it...?
Dyno run (2017)
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baz
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if you don't like it don't read it mate! why be so negative?
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A negative comment with a misspelled word ? The word is DRIVEL not 'dribble'. The young are so interesting when they start to criticise. I haven't seen anything on these pages I would describe as 'dribble'. If you don't quantify your improvements, how do you know you have improved ? The only reason I don't use a dyno, is I have not got one and I don't trust other idiots to use scientists' black boxes correctly.
This started out as a topic of interest, a mildly changed bike, RIDEN a lot, not just polished and trailered down to the dyno shop, with the owner trying to get optimum reliable performance out of it, and probably of interest to most of the people who use mikuni carbs. Most realize he's not going to get max horse power out of it, yet the usual group of DYNO THEORY EXPERTS have gone off on a theoretical explanation on how to get max horse power, without offering any real sound advice to the original task
Acotrel, when the crap starts running out of your mouth uncontrollably that's called dribble.
I will say no more because there is now a whole page of offended experts
Acotrel, when the crap starts running out of your mouth uncontrollably that's called dribble.
I will say no more because there is now a whole page of offended experts
The original post was a dyno graph of hp and torque for a motor with a Fullauto head (approx. $3000) and a PW3 cam (not mild in my opinion). The OP mentioned an unexpected dip in dyno graph.
Seems to me that this motor is expensively tuned and the original post invites comments on the anomalous dyno results.
I'm no expert and it seems that you are the only "expert" who is offended.
Ed
I'm not offended. I'm quite enjoying the rambling style of the replies.
Why do you think my motor is "expensively" tuned? All it has, apart from internal coatings and polishing, is the head and the cam. One could hardly call a VM 34 Mikuni a performance modification. However, while some may look at the graph and turn their noses up, this motor is an absolute delight to use. As I have said right from the start, six or seven years ago, the Commando's crowning glory is not its outright performance, but the beautiful creamy, grunty low end and midrange go. If you want fiery top end performance, look elsewhere. There is an absolute plethora of motorcycles ready and willing to provide that performance at your fingertips. Whilst the specifications of the PW3 seem to brand it as a top end race cam, in this application, it is an absolutely astonishingly tractable motor from right off idle, which, I think, comes down to the superior port velocities provided by the Jim Comstock port designs. I shake my head when I consider that this was the factory F750 cam in its day. Speaking to other users of this cam locally, they agree that it provides a lift in poke across the board, even with a standard head.
Dyno readings aside, on the road, where it counts, this motor is an absolute delight, with no lack of get up and go just about anywhere, with no beginning to the powerband. You twist it and the response is just strong from the getgo. This motor shines, not in the rev department, but the fact that you can hustle along maintaining a really good pace, but using somewhat less revs than you would with a standard spec bike.
A little update. I still don't have the O2 sensor hooked up yet. I only just got my pipe back with the bung welded on. I have gone a bit smaller on the air jet (#1.9), upped the pilot jet from a 40 to a 45 and gone down to a 230 main jet from a 240. Now much easier to start, runs beautifully but still a bit lean around idle. My TM 34 is ready to go, but I want to get the VM perfectly set up before I make the change, so that I'm comparing apples with apples.
Hi Ken,
I say expensively tuned because your Fullauto head is quite different from a standard Norton head and costs approx. $3000 US. Please understand I am not criticizing your product. On the contrary, I purchased two of them and I think they are wonderful works of engineering. I have one 750 ([HASHTAG]#193[/HASHTAG]) and one 850 ([HASHTAG]#201[/HASHTAG]) head and I am using them in two builds yet to be completed. I also have a PW3 cam that will be going into one of them.
And yes, I consider the PW3 to be more than mild. I don't say that it is race only.
My point is that someone interested in your original post, as I am, would be interested in any suggestions concerning improving what appears to be a performance dip on your dyno graph.
Ed
Fast Eddie
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Sure it’s strange Ken, but you’re being objective about it and you’ll sort it. And that’s why this thread is so interesting, for people to share the ‘cause and effect’ of what they saw, and did, and saw next, on the dyno.
I would never have realised my FCRs were weak on the needle without the dyno, and it’s disproved ‘seat of the pants analysis’ on many occasions for me.
Looking forward to your next instalment sir...
I would never have realised my FCRs were weak on the needle without the dyno, and it’s disproved ‘seat of the pants analysis’ on many occasions for me.
Looking forward to your next instalment sir...
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I would have thought that if your carburation was lean on the needle when you were using petrol, it would stand out like dog's balls when you were accelerating out of corners. There is probably a lot to be gained by trying several different taper needles. It is a direction I have not gone in with my motor. I use 6D Mikuni Needles in my Mk2 Amals running methanol. If it is slightly rich, the bit of extra sluggishness is almost imperceptible, so I have not bothered trying different tapers. If I lower the needles one notch, I get the miss when changing up and down through the gears. As you have said, I would not know if it was that bit too lean when it is running well.
Ken,
I will be using a pair of 932 Amal Premiers on at least one of the builds since I already have them. I'm leaning toward using Amals on both bikes but that will depend on what you find in your experiments and what others have achieved with similar set-ups.
Ed
Fast Eddie
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With ‘normal’ carbs, I’d agree with you fully. However, it has FCR carbs, which have accelerator pumps, this really masks the needle setting massively. The only time it shows up is when cruising on a steady state partial throttle opening. The kind of roads I use the bike on don’t really lend themselves to very much of that very often, often enough for me to suspect it wasn’t right, but not often enough to nail it. But on the dyno, it was crystal clear.
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Splatt, you are quite right to query the dyno figures so frequently tossed around on this forum. Rolling road dyno's are notorious for their inconsistencies across makes, and all are unable to replicate on road conditions when testing.
If Fullauto is happy with the performance of his machine, that is all that matters. Why should a dip in a dyno curve be a worry ? In all probability the dip is a result of the dyno test, and does not occur when riding on the road.
Fullauto
If it were not for the dip in the dyno curve, would you have ever thought there was anything amiss?
Absolutely not! It's a beautiful motor. Not as much top end as most people want, but,as I say, if you are chasing top end performance in a Commando, you own the wrong bike.
Fast Eddie
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That’s a tad opinionated Ken. And could be argued exactly the opposite way: if you’re chasing bottom end grunt you’re on the wrong bike... buy a Harley!
It’s all down to the personal preferences of the owner, there is no right or wrong.
It’s all down to the personal preferences of the owner, there is no right or wrong.
Didn't say there was Nigel. But if being opinionated means that I am expressing my opinion, then I'm opinionated. As for Harleys, I own an X1 Buell and the Norton motor is so much more tractable it's not funny. Maybe in the old days, Harleys were tractable, but they've extracted so much power from them over the years trying to keep up with somebody's idea of Nirvana, that they are somewhat less happy at lower revs than in previous incarnations. My Buell will not sit at 50mph in top gear. Before I got it sorted, you had to be doing 70mph before you could engage top and have smooth non jerky acceleration. That is not a tractable motor I'm afraid. But, it does have almost exactly double the horsepower of the Norton. Does that make it a more pleasant ride? Er, no. Now that you've mentioned Harleys, I'll give you my opinion, shall I?
I feel sorry for the true Harley aficionado, who has lived and breathed them over the years and knows exactly what he or she has got, instead of the total wankers who only know it's "a 2016 model", and is only ridden as some sort of make believe status symbol, reveling in their monthly polishing session, followed by a short ride down to the pub to show off to their mates and anybody who will look, dressed as they are in what I call, "the uniform of the individual".
My Norton is not a fad, or a fashion accessory, or something to pose on, and as soon as some unknowing individual remarks that my Norton is "cool", they have lost me in the conversation. The whole concept of "cool" to me is abhorrent, with the thought of somebody buying something so that they may appear "cool", is laughable to me in the extreme. I had a Norton in the 70s which I've always regretted selling, and throughout my life have yearned for another, which I purchased eleven years ago, never having regretted the sale of any other motorcycle which I have owned. My bike is clean, usually polished weekly and I receive a lot of comments on it, mostly positive. To me, I have put my soul into it, and a bucketload of money which I would never get back if I sold it. I jump on it at every opportunity, with the odo just about to click over 20,000 miles in twenty months. I ride it to work, to the shops or anywhere else I need or want to go.
Now, to my (opinionated) point. I rarely use the top end. I trundle around town or the open road, using the low end and fat midrange that Nortons are known for, with somewhat more in my case because of the changes made. When on the road, you use the low end and midrange ALL THE TIME, not occasionally like the top end. If you flog your Norton using high revs, I would surmise that you have no mechanical sympathy and that you are, indeed on the wrong bike! Not to mention the limited lifespan of the motor given such use.
The Norton is truly a motorcycle with which you can enjoy thoroughly the mundane tasks of everyday use. I literally would not swap my Norton for any motorcycle in the world, knowing that it would take at least two years to build another one, and at 62, I am not prepared to lose two years of riding to do it.
Anybody else feeling opinionated?
I feel sorry for the true Harley aficionado, who has lived and breathed them over the years and knows exactly what he or she has got, instead of the total wankers who only know it's "a 2016 model", and is only ridden as some sort of make believe status symbol, reveling in their monthly polishing session, followed by a short ride down to the pub to show off to their mates and anybody who will look, dressed as they are in what I call, "the uniform of the individual".
My Norton is not a fad, or a fashion accessory, or something to pose on, and as soon as some unknowing individual remarks that my Norton is "cool", they have lost me in the conversation. The whole concept of "cool" to me is abhorrent, with the thought of somebody buying something so that they may appear "cool", is laughable to me in the extreme. I had a Norton in the 70s which I've always regretted selling, and throughout my life have yearned for another, which I purchased eleven years ago, never having regretted the sale of any other motorcycle which I have owned. My bike is clean, usually polished weekly and I receive a lot of comments on it, mostly positive. To me, I have put my soul into it, and a bucketload of money which I would never get back if I sold it. I jump on it at every opportunity, with the odo just about to click over 20,000 miles in twenty months. I ride it to work, to the shops or anywhere else I need or want to go.
Now, to my (opinionated) point. I rarely use the top end. I trundle around town or the open road, using the low end and fat midrange that Nortons are known for, with somewhat more in my case because of the changes made. When on the road, you use the low end and midrange ALL THE TIME, not occasionally like the top end. If you flog your Norton using high revs, I would surmise that you have no mechanical sympathy and that you are, indeed on the wrong bike! Not to mention the limited lifespan of the motor given such use.
The Norton is truly a motorcycle with which you can enjoy thoroughly the mundane tasks of everyday use. I literally would not swap my Norton for any motorcycle in the world, knowing that it would take at least two years to build another one, and at 62, I am not prepared to lose two years of riding to do it.
Anybody else feeling opinionated?
Fast Eddie
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Well actually Ken, you did. You said that anyone chasing top end performance is on the wrong bike...
So, yes, in that case, I also feel opinionated...
You argue that if you want to go fast, there are other bikes out there that are better. I agree. But I also argue that if you want to ride around more slowly, focusing on smoothness and fuel economy, well guess what, there are plenty of modern bikes that will do that better than an old Commando too.
My point is, that doesn’t make your choice wrong, just like it doesn’t make alternative choices wrong.
I don’t ride my Norton like you at all. I don’t want to. It’s not why a built it like it is, and it’s not what I enjoy doing with it. I love it when it comes on cam at around 4K ish. Whilst it will comfortably rev to way in excess of 7k, for me, the sweet spot is between 4 and 6 and there is simply little to no advantage in revving higher than that. Keeping it between 4 and 6 is quite easy, even with the stock gearbox. Using the box in this way, and keeping the motor on song along a nice sweeping English A or B Road is simply a delight, an addiction that I can’t get enough of! And, given that the Commando was sold as the ultimate super bike of its day, I would also argue that it is exactly THIS type of riding for which it was initially designed and intended.
I’m changing my cam soon though, the new cam won’t come ‘on cam’ until probably 4.5k. Moving that sweet spot up the rev range by 500rpm, where it will be even stronger than it is now.
One thing to bear in mind for those who may not know, even though a motor like mine doesn’t come ‘on cam’ until 4K, it is still perfectly smooth and drivable below that. It has to be for me, as I live in a city and have to ride in traffic first whenever I want to get out on the nice roads.
As for mechanical sympathy, well, again that depends on your perspective. One type of sympathy is to treat the old metal gently, another is to strengthen it and / or replace it. In my case this means stronger cases, stronger crank and rods, forged pistons and a Maney outrigger.
But maybe you’re right, maybe I should just recognise that I have the wrong bike. Shame really, because I love it...!
So, yes, in that case, I also feel opinionated...
You argue that if you want to go fast, there are other bikes out there that are better. I agree. But I also argue that if you want to ride around more slowly, focusing on smoothness and fuel economy, well guess what, there are plenty of modern bikes that will do that better than an old Commando too.
My point is, that doesn’t make your choice wrong, just like it doesn’t make alternative choices wrong.
I don’t ride my Norton like you at all. I don’t want to. It’s not why a built it like it is, and it’s not what I enjoy doing with it. I love it when it comes on cam at around 4K ish. Whilst it will comfortably rev to way in excess of 7k, for me, the sweet spot is between 4 and 6 and there is simply little to no advantage in revving higher than that. Keeping it between 4 and 6 is quite easy, even with the stock gearbox. Using the box in this way, and keeping the motor on song along a nice sweeping English A or B Road is simply a delight, an addiction that I can’t get enough of! And, given that the Commando was sold as the ultimate super bike of its day, I would also argue that it is exactly THIS type of riding for which it was initially designed and intended.
I’m changing my cam soon though, the new cam won’t come ‘on cam’ until probably 4.5k. Moving that sweet spot up the rev range by 500rpm, where it will be even stronger than it is now.
One thing to bear in mind for those who may not know, even though a motor like mine doesn’t come ‘on cam’ until 4K, it is still perfectly smooth and drivable below that. It has to be for me, as I live in a city and have to ride in traffic first whenever I want to get out on the nice roads.
As for mechanical sympathy, well, again that depends on your perspective. One type of sympathy is to treat the old metal gently, another is to strengthen it and / or replace it. In my case this means stronger cases, stronger crank and rods, forged pistons and a Maney outrigger.
But maybe you’re right, maybe I should just recognise that I have the wrong bike. Shame really, because I love it...!
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