Petrol head thread!!!

[Icarus]

I must be the lucky one. You young 60+/- year old whippersnappers are having bouts with arthritis of the hands. My mornings with my hands are the same as you describe but the symptom waited until I was well past 80.  That really pisses me off until I get the fingers loosened up so that they function well enough.

I have not tried the paraffin yet.  Hot water soak works pretty well. In some cases I use epsom salt and hot water. 

[billy rubin]

i never had stiff fingers when i ran bees

i m getting stung again so maybe that will help

[billy rubin]

motor is together



even though te races have been postponed, i want to get this in one piece so i don't lose pieces of it. i'm guessing i'll have time to do new pipes now.

this particular motor is 50 years old (the frame it goes into is five years older), but it still pulls up to 135 mph. i need about four mpore mph to reach my own goals, but i don't think that will cme frm horsepower. i just need to practice getting smaller than i am to stay out of the wind.

this fellow managed to go 136 on this one, but his is a custom frame and the seating position below the wheel isn't legal for my class. still, he's only one mph faster than me, and i would heve beaten him had i not blown my motor up.

[Icarus]

Billy that dude is too big for LSR records.  The pretty lady he is with could go faster than that big brute. He has a cool looking scooter. The lay down handlebars are good for the purpose.  He has rear brakes..... I hope that your scoot has them too.

I am not too sure about the rigid frame layout at speed.

Did you know that round sections, like the fork lowers and uppers have a coefficient of drag of 1.2.  A rectangular section has a Cd of 0.8............Those numbers go against the usual perception of drag factors but true nonetheless.   So alright already you can't have rectangular fork lowers.  or.....could you?

[billy rubin]

he is indeed big. and his new bride is indeed a pretty woman. she has a brain, too, which is more interezting to me. hes not actually that big-- zhe is tiny

his machine runs in the altered class-- ooen-- any changez permissible. i run in modified production, which means i could put a license tag on mine abd run it on the street.

taking that kind of limited machine and beating the high zoot altered bikes is where i like to be.

i do have a back brake. not that i need it. but its there e. i have considered aerfoiled fo.j rk tubes, but there is not a lot acvailable except fir expensive antique vincent stuff. and i run rear suspension. its not really needed for pavement but comes in handy on poir surfaces like dry lakes or the salt.

mosrly i think i can get more bang for the buck by making myzelf aerodynamic. ive hit diminizhing returns on the machine, i think.

losing more weight will let me squeeze down flatter. the more the better.

[Dark Lightning]

Have you considered waxing the leathers (and everything else)? Maybe the run is too short to benefit from the air slipping over more easily over a waxed surface? Then again, maybe look at the surface of a golf ball. It's spinning in flight, though. I remember Kenny Bernstein's TF dragster having some sort of effects, as well. I don't follow drag racing any more, so I don't know if that helped him much. You're at a point where any speed gain is going to be a suite of incremental changes. Having to wait many months between trials is too long a time, and I'm betting you can't afford a wind tunnel. Are you allowed to "fair" the appendages that are out in the wind? Just tossing out ideas...

[billy rubin]

nobody in the real world can afford a wind tunnel, although ive sckured the net for dizcussions and results

the people who do wind tunnel work dont share what they learn.

havent thought about waxing. im not sure the viscosity of air is enough for that to help. certainly i could fair in the front forks with a fender. im allowed that while still stating within the naked class. no other aero devices in front of the rider are allowed.

i could add a stck headlight to sneak in a bit of rounding, but thats it.

the oeople who go very fast tell me that a front fender iz wasted until im going lots faster than 135. but i think ive added substantial slipperynezz by going with cast wheels. thats 80 round wire whirling spokes ive replaced with six aero vanes, and a reduced diameter as well.

disnt have a chance to tezt them much because i blew up on the firzt full power run.

[Icarus]

DL the waxing bit is fine for conventional noodling.  Doesn't work that way.  For example. waxing a sailboat bottom is sure to make it slower. That goes against conventional thinking. 

Boundary layer principle has the air closest to the surface adhering, or is in a stalled state.. Thinking in terms of layers of blankets or say onion skins, the farther away from the surface the faster the air flows and the discreet drag of the layers diminish.  In any case, BLs  "dirty" mess of pipes and motors and wheels and human bodies makes the whole thing problematic and practically undefineable........absent a wind tunnel. Even then the ambient conditions cause variables....Humidity, temperature, atmospheric pressure, and so on.

Early in my long ago college career I aspired to be an aeronautical engineer.  For practical reasons I dropped out of that specialty and into an ordinary mechanical engineering curriculum.  I did learn some stuff about how air and water impede the motion of solid objects during the Aero classes.   

[billy rubin]

the biggest problem with what i do is indeed the messy shape. its not hard to split the air open, but very difficult to smoosh it back together behind me.

the resut is that i carry a wedge of turbulence behind my ass at any real speed, and turbulence means low pressure.

low pressure means the impedence of the frontal area isn't balanced by an equal return at the back, and so the faster i go, the more i carry a negative force sucking me and my machine back into my wake.

the spinniong spoked wheels xert a similar problem, causing a squeezing effect of low pressure along the sides of the machine that th emotor must work against to move forward. i switched to aero three-spoke katana wheels to improve that.

none of this air pressure stuff is signioficant or even noticeable at lower speeds, but above 100 mph its the most important thing.

i could add a kamm tail behind me, and a fairing in front, andprobably go to 140-plus with no motor modifications. but that isn;t what i want to do.

i want to do it the hard way-- all tuning and rider skill-- making the run penetrate the wind by positioning my body at the optimum, and doing it with a 50 year old power unit.

this is like fly fishing. its not catching a ten pound fish that matters. its catching a ten pound fish on a three pound line.

[billy rubin]

and its a red letter day. the motor is back in the frame.



it always tajkes me three tries to do this, because i can't put the motor into the frame if the rocker boxes are on, and i cant pt the head bolts in if the motor mounts are tightedned.

the pattern is that i assemble the motor, try to put it in the frame, remember that i can't do it with the rocker boxes on. so i takeoff the rocker boxes, put it in the frame, tighten all he motor mopunt bolts, then remember tht the head bolts wont go in unless the motor is tipped to the side. so i take the motor mount bolts out, put in the head bolts, and then i put in th emotor mounts and tighten it all up.

i do this every single time, no matter how many times i put a motor together.

ive done it wrong so many times that the wrong sequence is the habit.

go figure.

stupid is as stupid does.

[billy rubin]

pushrods in, valves adjusted, oil in the motor. put the carbs on



this machine had old style amal carburetors on it when it was new. nice old instruments for their day, but limited in terms of tuneability by modern standards. some people prefer them and they can go pretty fast. the man i'm trying to beat uses amal GP carbs, an ancient 1950s design that got him up to 139.226 mph on gasoline.

i don't have any tradition that makes me want to use the old amals, so i run keihin FCRs, a jap[anese flat slide unit with an accelerator pump. excellent throttle response. the slide is on rollers so its friction-free, so i use them with just a pull setup, as opposed to the original push-pull. these things are light years ahead of the old amals in sophistication, but theyre still a 30-year-old design. big on racing two-stroke machines these days, and high-speed four wheelers.

one carb for each cylinder. this gives me maximum airflow, and makes the resonant tuning of the exhaust pipes easier, because there's no interference between cylinders in the return waves through the exhaust gases. stil, these carbs have quite a bit of reversion at aound 3000 rpm because of the open pipes. you can watch a cloud of fuel form around the bellmouth, get blown backwards and then sucked back in, corresponding with the mixture suddenly goinf rich. my solution is to just not ride that slow.

while the carbs are relatively space-age, the ignition is straight out of 1942



this is an old fairbanks-morse magneto, designed to run old stationary welders and industrial motors way back when my faily still ran mules. i think two cylinder john deere tractors ran them too. its mounted in an ARD magneto housing used by flat trackers in the 1960s.

magnetos are completely self-contained. this one is run by an enclosed rubber belt that takes its drive ff the exhaust camshaft.



its fixed advance, no retard function for low speeds, and so it used to be a bear to start. but the faster it turns, the hotter the spark. ive watched videos of people lighting cigars with these spark from these things on test mounts. i've messed with it in a number of ways, including slotting the mounting holes so i can adjust the ignition timing with a rubber hammer and switching to a no-rotor setup with forked spark plug wires that let me fire four plugs at once, two er cylinder.

i have an electronic ignition from new zealand for thismotorcycle, but i've never installed it because this magneto works so well. iits primitive, though,and under a timing light you can see a lot of spark scatter, maybe as much as four or five degrees. not a surprise for an ignition run by a rubber belt. but until i have no other options to go faster, i'll keep running this because its so simple.

[Icarus]

Billy the carb velocity stacks are almost surely too short.   I did a lot of experimentation way back in the dark ages.  Placing a tubular spacer between the carb and the intake port is a matter to be fiddled with.  I once managed to set a world record for 125 cc hydroplanes with this gimmick.

The deal is that when a wave front hits the atmospheric end of a tube, there is a reversion wave that is propagated back toward the origin of the pulse.  With just the right lengths of pipe you can get a positive surge of atmospheric energy that can help fill the inlet port.   You can do it with stacks but the pipes between the carb and the port can cause a very noticeable cooling effect of the induced charge. It is not unusual to see frost on the intermediate tube when the variables have been sorted.

So what is so interesting about a cool charge?  It can contain more O2 that a hot charge.  The more O2 in the combustion chamber the more fuel you can burn in a discreet power cycle.

Finally the Jap bikes have perfected the calm air box.  On the dyno I have seen considerable improvements in output with the calm air box as opposed to the stack bells being exposed to atmosphere directly.  You have to have a lot of turbulence going on right behind that head. That is not good for an ideal induction system. Consider doing something that can furnish calmer air to the intake bells. 

[billy rubin]

icarus, your observations on the intake are well taken. i've experimented a little with intake extensions





but i haven't explored it yet. all my time has been occupied farther forward. im a bveliever, though. my exhaust pipes are 34 inches long, and i lose 4 mph if i depart from that length two inches in either direction.  an air box would be useful, too, bot i havent tried to fabricate one yet. the carbs are splayed from the head and thereisnt much to attach a box to, so its not a simple job. one advantage of an airbox would be that i could clean up the confusion between the motor and the rear tire, covering the oil tank and keeping grit out of the carbs.

i dont yet even know whether i'll get to race this year. all the effort might not be worth it. if maine is shut down, i'll go to arkansas. thats less than 700 miles, as opposed to 1100, so thats a plus.

[billy rubin]

bang.

[Tank]

bang.

Excellent!