143MPH 850 MK1 Commando?

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Hobot is correct, both in his explanation of energy transfer loss factors, & his view re theory, -stick with it until proven otherwise, if any sound data emerges to dis-prove so be it...
 
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From Classic Bike, Feb `06, P.28, Re `74 J.P.N. Racers;
"Sometimes raced with short-stroke & 850cc engines."
 

SteveA

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SteveA said:
Rohan said:
Interesting post Steve.
Got a pic of your Rickman, or in action ?
http://www.facebook.com/photo.php?fbid= ... =3&theater

2 pictures here of original incarnation and 2 of the '79 version, all track pictures Cadwell Park, Lincolnshire.

Currently the original frame is back from repair and with the tank maker for a second new tank!, because after getting one made similar to the original I need a shorter and lower one to accomodate me today :roll:
Sorry if you can't get to these pictures, of course they are scanned '70s picture quality, if you want to friend Steve Adlem on FB (and I accept :lol: ) you will get to see them. I tried to join Photobucket yesterday but it said both my emails were already in use (unlikely) so no joy there, sorry. Will try again some other time.

Steve
 
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J.A.W. said:
Hobot is correct, both in his explanation of energy transfer loss factors, & his view re theory, -stick with it until proven otherwise, if any sound data emerges to dis-prove so be it...
hobot said:
Of course the *percentage* of drive train loss varies greatly with the input power
yet
hobot said:
Don't know how we could determine the drive train lost but its a constant that don't increase as power on it increasesso
and
hobot said:
If same drive train is used, then same hp drag to turn it to some rpm, regardless of the power plant turning it to same speeds.
so
hobot said:
so I think Nortons only loses about 10 %
I think there are enough words quoted above that if you rearrange a few of them you get the facts. I see your point :roll:
And if someone represents something as accurate or as fact or tries to build credibility by stating:
hobot said:
I've looked it up.
and someone calls them on it...........

My other point is that through all the diatribe I think hobot came around to an understanding; it just took several posts and iterations.
 

SteveA

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Trying to look at other ways of letting you access pics....

I put some in drop box and here is a link to that.....

https://www.dropbox.com/sh/4j1f35xdrts5txj/n0WJQYt40B

If you get in you see the red/white first build and a race at Cadwell Park in that trim, early '76.

2 pics of it as it was when I last raced it and as I sold it in '80.

1 pic of #33 which was as I found at Snetterton in 2007, with a different motor and box and fork legs and tank, well not much of it and the last pic is what I bought back in 2009 to start the project!

I Identified it by my RAF service number that I had stamped on the frame, yokes and engine plates (and pleny of other bits that were not there), and the manufacture date and pitting in the nickel plate that was always there, and marks I knew I made in the plate way back then.


Steve
 
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Confusing to discuss the cheese and chalk of this post, top speed vs power, so suggest we carry it on the post Jim Schmidt started on crank horse power. I have posted some of my references there, if you've desire enough to strain learning the terms and principles being confused -while accusing me of miss-understanding. I'm competitive as hell so a good looser so lets have it out there rationally for future references on reality checks.

crank-shaft-t14241.html

Just to worry ya ahead of time when picking on hobot in public -to put up or shut up-, I just spoke with a Calif. dyno shop to verify that if same dyno or drive train used, then its a constant power drag factor to add or subtract from all the engines tested on it... percentage will vary but not the total mechanical inertial drag resistance.
 
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hobot said:
Confusing to discuss the cheese and chalk of this post, top speed vs power, so suggest we carry it on the post Jim Schmidt started on crank horse power. I have posted some of my references there, if you've desire enough to strain learning the terms and principles being confused -while accusing me of miss-understanding. I'm competitive as hell so a good looser so lets have it out there rationally for future references on reality checks.

crank-shaft-t14241.html

Just to worry ya ahead of time when picking on hobot in public -to put up or shut up-, I just spoke with a Calif. dyno shop to verify that if same dyno or drive train used, then its a constant power drag factor to add or subtract from all the engines tested on it... percentage will vary but not the total mechanical inertial drag resistance.
This is like "whack the mole" game at the arcade; never know where it's going to pop up next. Ah yes, the un named inertial dyno guy in California, because the water brake dyno guy in Arkansas does not carry the credibility of California. Does this go with the unretreivable references you use. Your calling around like this suggests to me that you are uncertain and obsessed with your multitude of stances. There may have been an accusation that you misunderstood but I have a hunch you have some sort of grasp.

So just to confuse you more, for a given engine rpm of say 7,500, what are you saying if you double the load on a drive train because this is in the realm of a Norton (45hp versus 85hp). Before you answer keep in mind that you are dealing with a mixture of dry friction, lubricated friction, fluid friction and a less than ideal world.

I will stand by for your response or until I smell hickory smoke.
 
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DwS, WHERE is YOUR thesis to clearly demonstrate the irrefutable logic of your position?
 
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J.A.W. said:
DwS, WHERE is YOUR thesis to clearly demonstrate the irrefutable logic of your position?
Do you even know my position :lol: Besides, it's a dissertation.

It's the facts, nothing but the facts.

It's pretty consistent throughout.
 
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J.A.W. said:
DwS, WHERE is YOUR thesis to clearly demonstrate the irrefutable logic of your position?

+1. Seems a tad personal. At least Hobot is open to dialogue and admitting he might be wrong occasionally, not making accusations. I've noticed a lot of attitude towards Hobot and can't for the life of me understand it. Give respect to get it!
 
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DwS, I am not asking to see a copy of your PHD, a simple cogent post of your position setting out where you are demonstrably correct in your assertions - that`ll do...
 
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J.A.W. said:
DwS, I am not asking to see a copy of your PHD, a simple cogent post of your position setting out where you are demonstrably correct in your assertions - that`ll do...
Fair enough.

Though off the topic of the original thread, here we go:

The system is comprised of the primary chain, gear box, rear chain and tire.

Chains are listed as anywhere from 93% to 98% efficient so let's have a stab at it:
(for reference, another gentleman provided a similar analysis somewhere on this site)

Primary 93% to 98%
Gear Box 93% to 98% Should be closer to 98%, especially in fourth gear lock up
Rear Chain 93% to 98%
Tire to road 93% to 98% I have no idea what this number actually is
Product 75% to 92% System efficiency
Inferred loss 25% to 8%

So for a wild azz guess the system loss is likely between 25% and 8%.

I have heard a number bantered around over the years and 10 hp sticks; this is with a stock Commando configuration. As a weak arguement we have all heard Norton advertisements of 60hp for the 750cc engines yet rear wheel dyno is more like 45-50hp which supports the 10hp loss estimate if we assume Norton was advertising crankshaft Horse Power. Using the bounding analysis above of 25% and 8% renders 15hp and 4.8hp loss respectively.

Now to the point of whether loss is a constant for a system or varies based on power. Since power is a product of force times distance divided by time; a given rpm with two different power inputs means two different loads (forces). So in a frictionless system you can load it and load it and there will be no change but our poor Commandos are less than perfect so an increase in power (load) will result in an increase in loss, but not by a lot. How much of an increase in loss will there be if you go from 45hp to 80hp; I don't know but I do know that the loss is more sensitive to rpm. Most of the power increases on modified Nortons is around +20% to +30% over stock. If we accept the +20% to +30% as increased force or load and also understand that the friction loss is not linear (only a fraction of the increase in load) then you should see that a small fraction of +30% does not amount to a whole lot.

So what does this have to do with anything. Consider the chain drives and the vast variety of conditions the rear chain may be in; from rusted to slithery oily greasy. Sprocket conditions and dirt and chain stretch and chain tension all come into play. It is a real crap shoot as to exactly what your losses are at any given bike condition.

Bottom line is if you want to know, go with the rear wheel dyno and then compare it to a crankshaft dyno. By subtraction you will see the system loss for that motor and drive train. Do it again with a significantly more powerfull motor and I would expect you to see a greater net loss; probably not a lot more but noticeably more. In the mean time, 10hp loss at peak rpm is as good an estimate and more or less works as long as used across the board.
 
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Hehe Dances, this mole head is happy to see you throwing with in hobot's view on this. We both now agree that same drive train subtracts essentially the same amount of power no matter the amount of power fed in per rpm. We even both come up with similar ballpark figure, 4-6 hp from me, and your ~5 hp with more detailed data and calculations, i savored.

I've got to put together Peel's gear box this year and there's an old fart electric motor man not far away, so maybe I can get him to rig up 5 hp motor instead of crank shaft plus amp and volt guages on it and temp in the gb oil or shell and get a rpm drag graph to end the endless power pecking order conundrum. Then go WOT till no more and graph the dyno rwhp to top seed per gearing relationships with and w/o streamlining of various sorts. Also the sprints to distance or speed per above data points. Could take me til I'm 70 to get to it all.
 
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Classic Bike, July`12, P.16; Race meeting feature, Cadwell Park.
Has a yellow Norvil racer - Ian Gibson, owner/racer reckons "its always been a racer...may have been a works motor"- being an 850 with [unusually] a 270 degree crank, twin discs..
I.G. is quoted, "Its fantastic...very fast & the crank makes it smooth, with loads of low down grunt".
 

SteveA

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J.A.W. said:
Classic Bike, July`12, P.16; Race meeting feature, Cadwell Park.
Has a yellow Norvil racer - Ian Gibson, owner/racer reckons "its always been a racer...may have been a works motor"- being an 850 with [unusually] a 270 degree crank, twin discs..
I.G. is quoted, "Its fantastic...very fast & the crank makes it smooth, with loads of low down grunt".
Works motor claim seems unlikely. And 270 does not sound likely as a '70s fit.

Thruxton Motorcycles experimented with cranks, I saw some lined up on a shelf in a workshop on an Oxfordshire farm in about '77, belonging to Tony Smith who rode for them.

Apparently they went back to the original crank again and again, he said the 180 worked but revved enough to need expensive treatments and the valve gear was not up to it anyway....sounds familiar to me....

They included lighweight 360 cranks and the 180 cranks, I never heard of anyone doing 270s in the period, anybody else?
 
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[quote="SteveA"
Apparently they went back to the original crank again and again, he said the 180 worked but revved enough to need expensive treatments and the valve gear was not up to it anyway....sounds familiar to me.... quote]

Re; "and the valve gear was not up to it anyway...."


And would the light weight valve gear today be up to it; i.e. titanium valves, Triumph cam follows that are available :?:
 
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Peel tested 2S cam with K/W 6 mm stem valves of standard size and slightly lightened Norton lifter slugs and race springs to over 10,000 horrific rpm on stuck throttle no load till topped out, yet no evidence of loss of valve control even though it wore a cam lobe down in a few seconds. Schimdt has even lighter BSA radius lifter kit which should allow bigger valves to stay control even higher. Peel's head is being used again w/o any servicing needed but wider squish bands to accept 920 pistons. I found out early on - a stock CHO will float and clash valves some where in the mid red zone, which is also horrific to 1st discover on passing a semi with on coming gap closing fast. Horrific engine noise and mis firing with terrible lost of acceleration but lucked out didn't damage anything to stop the show once back below red zone and upshift.

One crank trick I've not heard of but in Peel so far is reducing the flywheel OD.
 
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Bernhard said:
[quote="SteveA"
Apparently they went back to the original crank again and again, he said the 180 worked but revved enough to need expensive treatments and the valve gear was not up to it anyway....sounds familiar to me.... quote]

Re; "and the valve gear was not up to it anyway...."


And would the light weight valve gear today be up to it; i.e. titanium valves, Triumph cam follows that are available :?:
[/quote][/quote][/quote]

It depends on revs, crank angle, inertial mass of valve train and valve seat load. I believe this is the predicament we put ourselves in with the 500cc Norton ultra short stroke and 180 degree crankshaft. In our case the cam is simultaneously opening two valves more or less at the same time; this puts enormous loads on the cam drive train and I suspect there's some additional snatch. Herb Becker converted the bike to a gear drive cam after breaking the drive chain. Our last upset resulted in a sheared crank pinion key, broken pinion gear and loose cam gear. In my opinion this configuration (revs, crank angle, inertial mass of valve train and valve seat load) has really put the cam drive train at its limit. Look at the key used for the cam of crank pinion, it is dainty. The crank pinion is really dainty. Wish we could use a slightly larger Triumph pinion as it has a little more meat on it but that is only part of the problem.

I honestly think you need to look at the whole package when making changes like crank angle.
 
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