Max sustainable RPM?

If I had a standard Commando, I would love it for what it is. The only thing I might do is trick the gearbox. If the gearbox is different inside, the bike would be much faster and the reason would not be obvious. Most of the hot-up stuff is a lot of garbage. What you gain on the hurdy-gurdy, you lose on the merry-go-round.
I would never paint a moustache on the Mona Lisa.
My own bike was built in my own head before I started creating it. It is not genuine in any shape or form, it just happens to resemble a Gus Kuhn Commando racer. It is however 'fit for purpose'. It is good enough to be competitive, and if you are near them, you can win. I do not need a million horsepower. As you get older, you become competent.
 
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Judging from what works with my bike, if you spent $750 to buy three gears and bought a few jets and needles, a standard Commando should be quick enough for anybody. The top three gears need to be close and high. Where first is does not really matter. When you go to pass somebody, if you only change down half a gear, the bike accelerates much faster. The standasrd box is hopeless.
 
ludwig said:
It is not the temperature in the oil tank that matters, but at the hottest point in the engine.
If the oil that is flowing from the head to the camshaft is at 150 °C, an oil cooler is not going to save it.
Putting burnt toast in the freezer won't make it edible.
There are a few things that can be done to make the cyl. head run cooler.

This is an old article from Alan Goldwater, but it is still relevant :

Another reason why a std 850 cannot be ridden fast over long distances is the exhaust.
It will inevitably crack, rattle loose, or fall off all together.
During the 80-ties, I used to visit the Bol d'Or 24h at the Paul Ricard race track, France
and ride back on Monday to my place in Belgium:
1100 km in around 10 h riding time. I always came home with cracks in the exhaust pipes, till I bolted the mufflers rigid to the engine cradle, and did away with the rose nuts.
5500 rpm "all day long" .. Really?
In my experience, a reliable max cruising speed is more like 4500 rpm.
And even then, don't think too much about all those parts rattling inside your engine, or you will automatically slow down..
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The motor in a Commando moves around much more than the motor in other bikes. With a race bike, everything must be rubber mounted, even with a rigidly mounted motor. My exhaust system fits to the head with slip joints and springs.
 
Ludwig,

I think I was on that ride to Sacramento with Alan. I’ve been using Redline synthetic ever since. The popular oil everyone was using was Castrol GT 20w50. One or two members put Castrol R in the gas, but mostly for the smell ;)
 
ILLF8ED said:
Ludwig,

I think I was on that ride to Sacramento with Alan. I’ve been using Redline synthetic ever since. The popular oil everyone was using was Castrol GT 20w50. One or two members put Castrol R in the gas, but mostly for the smell
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Which Redline Synthetic oil are you using?
 
concours said:
I'd like to read more about that!
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I'll see if I can find some reading material on that. The whole story of the Picador engine development was published in a series of articles in the VOC monthly magazine "MPH" many years ago. It has largely been forgotten now and Vincents are back to their "Forth Bridge" mythology.

From time to time I remind fellow Vincenteers that their original Vincents aren't really the strongest candidates from which to build a high revving , fire breathing monster. That information isn't always appreciated, in fact some owners get right pissed off at me. I'm just trying to help them avoid destroying a perfectly good but ancient engine and perhaps the ancient rider as well.

Sounds familiar? :)

Glen
 
worntorn said:
I'll see if I can find some reading material on that. The whole story of the Picador engine development was published in a series of articles in the VOC monthly magazine "MPH" many years ago. It has largely been forgotten now and Vincents are back to their "Forth Bridge" mythology.

From time to time I remind fellow Vincenteers that their original Vincents aren't really the strongest candidates from which to build a high revving , fire breathing monster. That information isn't always appreciated, in fact some owners get right pissed off at me. I'm just trying to help them avoid destroying a perfectly good but ancient engine and perhaps the ancient rider as well.

Sounds familiar? :)

Glen
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Sounds VERY familiar. Thank you
 
The max on my venerable ole 850 is 5000 and lower. She may get a sustained 4000 if we both feel frisky that day.... We're both getting too old for taking risks, and the sustained is always less than 5miles.
 
The rev range I use with my Seeley 850 is between 5,500 RPM and 7,000 RPM. It runs perfectly at that. By why would you want to do that on public roads ?
It is possible to change the crank balance factor on a road bike, but it would be horrible in slow traffic - and that is probably the most common condition, in which most road bikes are used.
With a four cylinddr motorcycle, you can have good performance at both high and low speeds.
I think Norton Commandos are lovely bikes, but they are what they are. You ride them for the happy experience.
My Seeley 850 is a pig at low revs, but when it comes on song, i get a superb adrenalin rush. It can really carve-up most four cylinder motorcycles in it's race class. It gives a really beautiful ride.
If I want to really have a go, it is there at every instant. It races in a pre-1972 class, but it is faster than a Z900 Kawasaki, and is a much easier ride.
 
Many years ago, I was racing at Mount Gambier in South Australia, and met a guy who was racing a 650SS. He told me he has a Seeley Commando similar to my own, which he does not race. When he races the 650SS, he has to work harder, so he has more fun.
 
AL really my 850 motor is balanced at 72% and hard mounted in the Featherbed and its quite smooth at low RPM I can ride around town/suburbs in top gear at 40mph without any problems at all any lower I got to drop it into 3rd and on the open roads it cruises pretty smooth between 70 to 90 all day if I want, it does get a few vibs at curtin revs but just going through those areas it smooths out again, my days of high speeds are over and knowing my Norton will go well over the ton I am happy the way it's built and nothing falls off and the best thing I get to take it out when ever I want, how long has it been for you.
Sometimes AL you talk about things you have no idea at all, my motor will rev freely from low RPMs to high revs but do in need to do 8000 RPMs and when I do stick it into it through the gears it surprises a lot of modern bike riders, I have nothing to prove but I have a lot of fun on this old bike of mine.
Same as my 1200 Thruxton nothing to prove but I just love the torque of that smooth running bike love both bikes for what they are, for my enjoyment and nothing else.
No use having a bike sitting in the shed and dreaming about how good it was in your eyes only, maybe it's time to pass it onto someone who will ride it, put a stock gearbox in it and some lights and ride it when you feel like it instead of talking about it, you don't need high speeds to enjoy your bike or riding around circles on track.
 
worntorn said:
Which Redline Synthetic oil are you using?
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This one.
Max sustainable RPM?
 
Then you might want to look at Jim's testing results. One version of Redline synthetic that he tested came out rather poorly. See " Redline 20/60 Synthetic" below.

On the other hand, the Red line straight 60 weight in the " Racing Oil" variety did very well. I don't think we want to run 60 weight in normal running though.

Screenshot_20230416_170901_Chrome.jpg
Screenshot_20230416_170839_Chrome.jpg
 
acotrel said:
The rev range I use with my Seeley 850 is between 5,500 RPM and 7,000 RPM. It runs perfectly at that. By why would you want to do that on public roads ?
It is possible to change the crank balance factor on a road bike, but it would be horrible in slow traffic - and that is probably the most common condition, in which most road bikes are used.
With a four cylinddr motorcycle, you can have good performance at both high and low speeds.
I think Norton Commandos are lovely bikes, but they are what they are. You ride them for the happy experience.
My Seeley 850 is a pig at low revs, but when it comes on song, i get a superb adrenalin rush. It can really carve-up most four cylinder motorcycles in it's race class. It gives a really beautiful ride.
If I want to really have a go, it is there at every instant. It races in a pre-1972 class, but it is faster than a Z900 Kawasaki, and is a much easier ride.
Click to expand...
The post is about maximum sustainable revs
Not about racing!
 
baz said:
The post is about maximum sustainable revs
Not about racing!
Click to expand...

No matter what its all about AL only talks about racing as he is to scared to ride on the road and its been so long since he has ridden a motorcycle so he only has memory, any old bike will struggle to maintain maximum speed or flat out, but our old Norton's will sustain 5000 to 5500 RPMs for a lot of miles and do it easily between 70 to 90 MPH on any long trips if your in a hurry but can the body withstand 90 MPH on any long distants in a sit up or lay down position.
 
ashman said:
No matter what its all about AL only talks about racing as he is to scared to ride on the road and its been so long since he has ridden a motorcycle so he only has memory, any old bike will struggle to maintain maximum speed or flat out, but our old Norton's will sustain 5000 to 5500 RPMs for a lot of miles and do it easily between 70 to 90 MPH on any long trips if your in a hurry but can the body withstand 90 MPH on any long distants in a sit up or lay down position.
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This is why I fitted a flyscreen
 
ashman said:
Hey Baz, man up a fly screen on a Norton, be real lol.
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If I didn't have a disc out of alignment in my neck I wouldn't have a flyscreen believe me
But it does take it off you when you are sitting at 90mph
 
baz said:
If I didn't have a disc out of alignment in my neck I wouldn't have a flyscreen believe me
But it does take it off you when you are sitting at 90mph
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I'm glad you got one ...as it will save me fitting one..🤣
Practical solution👍and when ya hit a swam of bees etc ...then im jealous
 
  • Haha
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