Petrol head thread!!!

[Dark Lightning]

Cool beans, Billy! My racing days are way past.

[billy rubin]

lol

i discovered myself on youtube

i have no idea who took this

[billy rubin]

Cool beans, Billy! My racing days are way past.

i am 67 years old and start slow because it takes me a while to get my feet up on the pegs and i dont fold easily

but once im up with my feet in positiion, all i have to do is open the throttle and hang on.

youre only old if you cooperate

and it helps to lie to yourself

[Dark Lightning]

lol

i discovered myself on youtube

i have no idea who took this

Makes me think of "Vanishing Point", but you got to come back! 

[Tank]

Loving your updates!!!

[MarcusA]

Dreams of Mad Max!

[Icarus]

Billy, I/we are pleased that you survived the event in Maine. You are a plenty smart dude and doing that LSR stuff aint so smart. That said I do appreciate your reporting and the descriptions of your work on the bike.  In fact I get some vicarious thrills from your descriptions. Thank you for that.

Something tells me that you are going to continue your quest.  I have been thinking about possible ways to get that last little bit from the Triumph. Here is the deal. That rig is aerodynamically extremely dirty. I would guess that it has a drag coefficient of 0.75 or thereabouts. Terrible! 

Lets examine the force needed to go from your previous 134 to the sought after 140
The drag equation ....D = (rho x Area x Cd x Velocity squared)/2.... With air density rho, area, and Cd fixed, then velocity becomes the major item of influence.  If we do the arithmetic it will be discovered that we need eight and a half percent more force to get from 134 to the 140 mark. 8.5% is a lot to ask from that engine because you have already approached the limit of what can realistically be expected from all your modifications. There  may be a little bit more in there if you trash that damned mag.  8 or 10 percent is a lot to ask at this stage of the game. and make damned sure the fork caps are not broken.

Here is a vid that discusses aero drag for bikes. https://airshaper.com/videos/motorcycle-aerodynamics/qrH_QBOrqbw

Your Cd can be improved in several ways. I suspect that the stock fuel tank might improve the Cd a little bit....for starters. All those wheel spokes make a mish mosh of the airflow. I have even had pipe dreams about a drag coefficient measurement method that could be put together out there in the woods, without great cost. It would be crude and inconclusive but maybe fun to play with. 

Imagine that you have a big fan that could move a large volume of air. Suspend the fan by two ropes or cables such that the base of the fan is very close to the floor. We are going to measure the force that the fan has to exert rather than have the bike on some sort of measuring platform, like a real wind tunnel does. Isaac done tole us about equal and opposite force. The fan will swing rearward some amount when exposed to resistance. Tape a little laser pointer to the fan and aim the beam at the floor. A tape measure or yardstick under the laser beam........Measure the movement of the fan when you are on the bike in whatever positions you assume. Flow straighteners could be made from sheets of plywood. I am just spitballing here so forgive me for dreaming up Rube Goldberg stuff.

When I was messing with the KZ750 the engine output was boosted a plenty. Hmmmm, the damned clutch was slipping when at speed. I had to put some hellacious springs in the clutch to fix the problem.   What if your clutch was behaving like that? The Triumph clutch was barely adequate in its original stock form. Are you old enough to remember when Armstrong began  producing clutch plates for bikes? They were far better than anything the Brits had furnished. Yep, Armstrong is the outfit that was more famous for producing linoleum flooring.  Scuse me, I became distracted by that bit of nostalgia.

Then there is tire traction to be reckoned with. If all else is delivering and there is some drive tire slippage........... you get the idea. Fat rear tire, maybe even a slick might be appropriate. At 100 plus MPH the chain is working pretty hard and it is transmitting a huge lot of force. If the chain stretches even a little bit, it will, then the rollers and the sprocket may not fit perfectly and ...............well there are too damned many things to think of and work on.

[billy rubin]

youve brought up some useful points. i have a 40mm bob newby 6-spring clutch in there that i have cranked down pretty hard. its designed for more powerful machines than ui have, so i dobnt thnk the problem is slippage. theres never been any rpm change under load.



id like to install the katana wheels too, becaause i know that th e40-spoke triumph wheels generate a turbulent zone to each side that the sipstream squeezes. i have these to put back on after i solve the bearing issue



but ike you said, the biggest issue is really aerodynamics. on an open machine like this where the rules dont permit a fairing, the biggest source of drag is me, and my riding position. heres the guy im tryiong beat- 139.266



he gets lower than this, but not lower than me. the old road racers used to say that if you got your back intothe perfect position, the slipstream would not detach from your back and it would suddenly go cold. ive felt that one time.

so right now im concentrating on getting everything in the motor going right and seeing if i can twist my body better

i do have a major fan in th ewarehouse, and old rooftop blower with an 18 squirrel cage and a 3/4 hp motor. it will blow a solid stream of air strong enough to do what you suggest. i will think about that.

another thing i have done is gotten on the machine with my kids taking photos from a distance so i can look at the image and see what sticks out. other people use a bright light to cast a shadow on the wall, then measure the surface are.

lots to do still. the electronic ignition is first. i was going to look at it tomorrow but i have to work

[Icarus]

The contest is between available force and resistance to that force. There is a progression where the engine provides a  varying force that is limited to whatever maximum force it is capable of developing. On the other end of the see saw, is the resistance part.That one is variable but not limited. Somewhere on the graph curves of force vs resistance, the lines cross. At that point you cannot go any faster.

You are flogging the engine pretty hard, maybe near or at its' practical limit. If that is so, then the only alternative is to attack the resistance curve and its causes. Aero is the major part of the calculations but there are numerous other tiny little details that can be addressed. Chains, sprockets, tires, axle bearings, and a whole list of other things to attend to with great detail.

Aero: your carcass is likely to be one of the main producers of drag. Not necessarily the largest of the drag producing objects. Fixing some smaller and less obvious drag producers are worth attention.  An example is the way you have routed the control cables...throttle, clutch, etc. The location and shape of the fuel lines, plug wires,foot pegs, and more. Are you aware that wires or cables generate a drag number that is far larger than would be presumed? 

I know a little bit about drag on cables because of my research concerning sailboats and how to coax them to go faster. Most sailboats have wires called shrouds and stays. When the wind blows they vibrate and sometimes make a screaming sound. If they vibrate they must have some force that causes that motion. We are using energy to drive the boat but wasting some of it because of something as apparently innocent as wires.

OK so wires, or cables, are not a big deal. They are a little deal but the sum of a lot of little deals adds up to a larger deal. The best part of the research and remedies that you might do, is that the fixes are inexpensive.  Did you know that rectangular fork legs create less drag than round ones, within the velocity ranges in which you operate?  That is counter intuitive but verifiable none the less. Not to suggest that you change the fork legs. That damned magneto up in front of the cylinder base will generate a mess of turbulence. Find places or things that can be eliminated or re-positioned in such a way as to minimize turbulence. It takes energy to generate turbulence...nuff said.

When I was in university, my intent was to gain an aeronautical engineer degree. I changed my major for several reasons. One of them was the that the dean of the school was a retired navy jet pilot. He wanted to find ways to make planes faster. I wanted to find ways to reduce aero drag of 18 wheeler rigs. We clashed. In any case I became hung up on drag stuff. I might mention that, at that time, I was also looking for ways to let my NSU Supermax race bike go faster down the straights. The professor was not sympathetic about such worthless,to him, stuff like that.

You have a whole year to brainstorm about the many little things that you can do to lessen the total resistance of the air and the mechanical parts. If I survive, I will be one  your cheerleaders.  I will probably continue to annoy you about tiny details.

[MarcusA]

billy rubin, have you watched The World's Fastest Indian with Anthony Hopkins? It could be good for you to watch another maniac on a motorcycle.

[billy rubin]

yes. how could i miss that? hes famous and his record still stands.

in the real world it took him more than one try to get to 200 mph though

beseides, hopkins is a superb actor

[billy rubin]

The contest is between available force and resistance to that force. There is a progression where the engine provides a  varying force that is limited to whatever maximum force it is capable of developing. On the other end of the see saw, is the resistance part.That one is variable but not limited. Somewhere on the graph curves of force vs resistance, the lines cross. At that point you cannot go any faster.

You are flogging the engine pretty hard, maybe near or at its' practical limit. If that is so, then the only alternative is to attack the resistance curve and its causes. Aero is the major part of the calculations but there are numerous other tiny little details that can be addressed. Chains, sprockets, tires, axle bearings, and a whole list of other things to attend to with great detail.

Aero: your carcass is likely to be one of the main producers of drag. Not necessarily the largest of the drag producing objects. Fixing some smaller and less obvious drag producers are worth attention.  An example is the way you have routed the control cables...throttle, clutch, etc. The location and shape of the fuel lines, plug wires,foot pegs, and more. Are you aware that wires or cables generate a drag number that is far larger than would be presumed? 

I know a little bit about drag on cables because of my research concerning sailboats and how to coax them to go faster. Most sailboats have wires called shrouds and stays. When the wind blows they vibrate and sometimes make a screaming sound. If they vibrate they must have some force that causes that motion. We are using energy to drive the boat but wasting some of it because of something as apparently innocent as wires.

OK so wires, or cables, are not a big deal. They are a little deal but the sum of a lot of little deals adds up to a larger deal. The best part of the research and remedies that you might do, is that the fixes are inexpensive.  Did you know that rectangular fork legs create less drag than round ones, within the velocity ranges in which you operate?  That is counter intuitive but verifiable none the less. Not to suggest that you change the fork legs. That damned magneto up in front of the cylinder base will generate a mess of turbulence. Find places or things that can be eliminated or re-positioned in such a way as to minimize turbulence. It takes energy to generate turbulence...nuff said.

When I was in university, my intent was to gain an aeronautical engineer degree. I changed my major for several reasons. One of them was the that the dean of the school was a retired navy jet pilot. He wanted to find ways to make planes faster. I wanted to find ways to reduce aero drag of 18 wheeler rigs. We clashed. In any case I became hung up on drag stuff. I might mention that, at that time, I was also looking for ways to let my NSU Supermax race bike go faster down the straights. The professor was not sympathetic about such worthless,to him, stuff like that.

You have a whole year to brainstorm about the many little things that you can do to lessen the total resistance of the air and the mechanical parts. If I survive, I will be one  your cheerleaders.  I will probably continue to annoy you about tiny details.

lots here

i will get back

[billy rubin]

for the moment, found a place for a battery in front of the breather catch bottle and below the oil tank



its not easy finding places for stuff on this thing. its mostly just two wheels, a motor, and a seat.



then i could nt find a place for the transistor box, bso i bolted it to the seat pan where it will  ne accessible but out of the wind under my belly

[Icarus]

Good going Billy. Keep thinking.

[Icarus]

The number plate encloses the top of the rear wheel.......Maybe lowering the rear end of the plate to allow air pressure to escape the top of the wheel...Just brainstorming here...

Your pipes are really short. That is typical of high rev engines. A bunch of hot air comes out of the pipes.. Is there any way to utilize that tiny bit of thrust? or maybe deflecting the flow away from the rear wheel.....just grasping at straws in the wind....

That blunt ended, both ends, fuel tank annoys me. Sure, it is adequate for fuel enclosure but that is not the sum of its usefulness or its harm.

Could some sort of configured pad on the top of the top frame bar, be configured to clean up the air on some of the other bits and pieces nearby.... the ones below the pad. Or on or near your belly. Surely a pad could be within the rules.

The problem with cleaning up small airflow parts,is that improving one thing may cause an increase of drag on an adjacent thing. All that on a naked bike will surely need a lot of head scratching.

Keep thinking. Apologies; I will probably continue to interfere with your thought processes. Maybe DL will weigh in here. He is a physics guy who knows a lot of stuff, including aerodynamics.