Hawk Talk - Page 17

pete · 12-02-2016, 08:29 PM

[QUOTE=Ghenghis;2372

Some people dimpled their entire intake like the surface of a golf ball. Dimples on a golf ball are there to reduce it's wake as it moves through the air so they fly straight, a large wake causes irregular turbulence causing a sphere to change direction. Jury is out on that method, unsure if you'd see any difference over roughing up the intake surface, intake air isn't exactly moving around a sphere. I suppose you could dimple your choke plate...

Keeping the heat in your exhaust flow results in a higher velocity which has a scavenging effect on the next exhaust cycle. Wrap those exhaust pipes and smooth out those burrs!

I'm tired now.[/QUOTE]

It's called the "Magnus effect"... only comes into play when the sphere is spinning..
is why a tennis soccer player or baseball pitcher can turn the ball in flight...
it produces a low & high pressure area on opisite sides of the sphere .. high pressure side pushes the sphere into the low pressure side turning the sphere in flight.. also why muskets & canons had unrifled
barrels to stop the musket ball spinning 'turning in flight"
they used this force to power a ship... if intrerested google "flettener rotor"

nature knows best..... sharks have a rough skin for this very reason
it traps a thin layer of water that makes the shark very smooth & slipery..

exhuast wrap... hotter the exhuast gasses the thiner they are so they can travel
faster...

....

Ariel Red Hunter · 12-03-2016, 09:38 AM

Quote:

Originally Posted by pete

It's called the "Magnus effect"... only comes into play when the sphere is spinning..
is why a tennis soccer player or baseball pitcher can turn the ball in flight...
it produces a low & high pressure area on opisite sides of the sphere .. high pressure side pushes the sphere into the low pressure side turning the sphere in flight.. also why muskets & canons had unrifled
barrels to stop the musket ball spinning 'turning in flight"
they used this force to power a ship... if intrerested google "flettener rotor"

nature knows best..... sharks have a rough skin for this very reason
it traps a thin layer of water that makes the shark very smooth & slipery..

exhuast wrap... hotter the exhuast gasses the thiner they are so they can travel
faster...

....

Yeah, Pete, mentioning sharkskin explains the issue perfectly. That's why polishing the inlet tract in the head is a poor idea. Polishing inlet tracts was a big deal in the 1920's and 30's. They got better performance because the inlet tracts in those days were rough castings, so any smoothing of ports made a big difference. A pressure die cast alloy head is not the same thing as a sand cast iron head. Because, for cost reasons, and production numbers, they took great care in designing the die cast molds. When they ran these engines on the dynos, and then polished the ports, the polished port engines were always a little lower in output. Took a while to figure out why. This little engine has a really great die cast head. Actually all of the castings are a tribute to the foundryman's craft.

Jmcgee · 12-03-2016, 01:30 PM

http://www.eastwood.com/images/email...ting_Guide.pdf

Ariel, you are correct, I was reading this, it states you want about an 80 grit finish on the intake, and a polished exhaust.

Ariel Red Hunter · 12-03-2016, 02:45 PM

Quote:

Originally Posted by Jmcgee

http://www.eastwood.com/images/email...ting_Guide.pdf

Ariel, you are correct, I was reading this, it states you want about an 80 grit finish on the intake, and a polished exhaust.

Yes, and polish the combustion chamber too. Just don't over do it. Leave the old valves in the head in order to protect the valve seat while you are polishing.

timcosby · 12-04-2016, 07:16 PM

on a less serious note i was watching z nation the other night and the girl was riding what looked to be an older type hawk and if you watch real close the brake caliper switches sides of the wheel a couple times! to make the bike look like it was going in the right direction the editor had mirrored the scene which is like looking in a mirror. you could see the exhaust changed sides too.

Ariel Red Hunter · 12-06-2016, 05:56 PM

I mentioned before sweet running, tireless engines. For may years, motorcycles were compared to horses, which is probably where that phrase comes from. A sweet motor cycle is one where the parts all seem to work in harmony. You don't have to think about what to do, it virtually seems to read your mind, and responds to your every thought. Maybe the modern phrase for this is fly-by-wire. Now I, and many others who grew up in the west, were born to the saddle. At least of my generation. I'd probably ridden four or five different horses before I rode one where I had that eureka moment of understanding how wonderful that experience could be. And once you have experienced it, you look for horses that you can develop that feeling of oneness with. Makes it easy to ride. And you can maintain higher average speeds with such a mount. Suprisingley, motor cycles are much the same. I'd ridden other motorcycles that I had never had that feeling of oneness with until I got my Red Hunter. I never had that feeling on a Harley-Davidson, but now that I'm thinking about this, that may explain the mystique of the Indian, it was that kind of bike. Japanese bikes I have owned were marvelous mechically, but never had that kind of soul. If you had ridden a Speed Twin, you were never all that impressed with to 450cc Honda twin. There was nothing really wrong with the 450, it was just not as sweet as the Triumph. As wonderful as the Yamaha 650 twin was, it was never in the class of a Triumph Thunderbird, or a BSA Super Rocket. They just lacked that fly-by-wire feel. The Hawk is a bike that approaches that hallowed ground. You have to manipulate a few things, but you can get there, if you want. So don't just drive it, ride it.

BlackBike · 12-06-2016, 09:46 PM

good one arh.

Ariel Red Hunter · 12-06-2016, 10:53 PM

Quote:

Originally Posted by BlackBike

good one arh.

Tnx!

hertz9753 · 12-07-2016, 12:52 AM

I thought you would enjoy that.

Ariel Red Hunter · 12-07-2016, 11:38 AM

Quote:

Originally Posted by hertz9753

I thought you would enjoy that.

Well, I enjoyed it, that's for sure!

edit: listening to mr obvious and the snowblower the second time through was even funnier!

Ariel Red Hunter · 12-10-2016, 01:15 PM

Yeah, but there is not a ton of them. I'll start with what is probably the most controversial: A K-model Harley Davidson. WHAT? Yeah, I know, flat head v-twin. But that is the problem with guys that read more into spec sheets than is really there. There are bikes that talk the talk, and then there are bikes that walk the walk. Kinda' ugly, stock. But what a street tracker you can build out of one of these. Bullet proof transmission. Bullet proof electrical system. Bullet proof clutch. Very tough engine. One of the first bikes with a swinging arm rear suspension. The first big bike with a unit power plant (engine and transmission in the same unit). Virtually unbreakable rear chain. Good handling, for the day. Fast enough for me. The handling was good because of the engine. Being a flathead, all of the weight was down low. The specs don't tell you that. That engine is infinately tuneable. ALL KR parts interchange. Oh, I forgot. Easy starting. Yeah, I wish I'd bought one. I have

owned a Sportster, and I've ridden a couple of K's. The K was a superior bike in my opinion.

Ariel Red Hunter · 12-10-2016, 01:37 PM

Next would be a Velocette MSS. Superb handling. Not fussy. Fast enough, though not really fast. Sort of a real symphonie of parts, made in a small factory, designed by two brothers who owned Veloce Limited. Everything about it contributed to the whole. I had a chance to buy one for short money, but I was tap city at the time. Next, a Bultaco Matador - and I don't even like two-strokes. Another machine made in a small factory in which all the parts all together made a superb whole. Oh yes, a 500cc Cotton. Just because they were so uniquilley beautiful, AND it had a fire breathing J.A.P engine. Light. Superb handling. Lycette saddle. Girder forks. Made in small numbers from 1929 to 1948. Really doesn't look like I missed out on much, does it.

Ariel Red Hunter · 12-13-2016, 01:46 PM

And it's many brothers and sisters that use the same engine. Luckily for short money guys (like me), foundry technique had progressed to the point to when these engines were first built they already had superb head castings in mass production. Die cast aluminum heads started in the 1930's with radial aircraft engines. You can see, perhaps, the advantage of die cast heads from a production standpoint of engines that required 7 or 9 or 14 or 18 or even more identical heads per engine. By the time WW11 rolled around, die cast heads were in common use. And these were 2nd or 3rd generation heads. Which meant that the intake and exhaust ports were much more sophisticated. The big time manufacturers of the radial engine were Wright, Pratt & Whitney in the US, Bristol in England, and BMW in Germany. Not to forget radials used in Zeros in Japan. So, from this experience came the first die cast heads for motorcycles in the early 1950's in England and Germany. It took 2 or three generations of making die-cast heads in the MC Industry to really get the porting right. Honda did a superb job of designing heads by the sixties and beyond. So the head on the Hawk was perhaps a fifth generation design. And these heads are superb. That's why I'm not in favor of doing port work on them. From the mid-fifties on, virtually every engine design department did a lot of flow bench work on each new generation head. The beauty of die casting is, once you have something that really works, you can re-produce this in the millions. And the engine used in the Hawk is the beneficiary of this outstanding head design. Now, when some manufacturer has a frame and chassis he wants an engine for, they have a tendency to not understand the interplay between the intake system, the head and the exhaust system. Or, in engineering terminology, the effect of the interplay of these issuus on B.M.E.P.. Brake Mean Effective Pressure. How do you get more BMEP? Reduce to the minimum air flow restrictions on the intake side, and do everything you can to improve exhaust flow, and jet the carburetor accordingly. Next, if you want to spent the money, more compression ratio. The cam used in this engine is more than adequete to do the job. After all, the engine spins right on up to ignition cut off speed, so getting adequete cylinder filling at high rpm is not the problem, the problem is to get more bang for the buck, ie better BMEP, so you get some more bang per firing shot. Focus on this, and you will be sucessfull.

pete · 12-14-2016, 04:48 AM

Quote:

Originally Posted by Ariel Red Hunter

I mentioned before sweet running, tireless engines. For may years, motorcycles were compared to horses, which is probably where that phrase comes from. A sweet motor cycle is one where the parts all seem to work in harmony. You don't have to think about what to do, it virtually seems to read your mind, and responds to your every thought. Maybe the modern phrase for this is fly-by-wire. Now I, and many others who grew up in the west, were born to the saddle. At least of my generation. I'd probably ridden four or five different horses before I rode one where I had that eureka moment of understanding how wonderful that experience could be. And once you have experienced it, you look for horses that you can develop that feeling of oneness with. Makes it easy to ride. And you can maintain higher average speeds with such a mount. Suprisingley, motor cycles are much the same. I'd ridden other motorcycles that I had never had that feeling of oneness with until I got my Red Hunter. I never had that feeling on a Harley-Davidson, but now that I'm thinking about this, that may explain the mystique of the Indian, it was that kind of bike. Japanese bikes I have owned were marvelous mechically, but never had that kind of soul. If you had ridden a Speed Twin, you were never all that impressed with to 450cc Honda twin. There was nothing really wrong with the 450, it was just not as sweet as the Triumph. As wonderful as the Yamaha 650 twin was, it was never in the class of a Triumph Thunderbird, or a BSA Super Rocket. They just lacked that fly-by-wire feel. The Hawk is a bike that approaches that hallowed ground. You have to manipulate a few things, but you can get there, if you want. So don't just drive it, ride it.

It's all pretty simple realy... but meany riders don't know

when cornering ...
Road - keep yer weight below the bikes centre line... weight the inside peg...
Dirt - keep yer weight above the bikes centre line... weight the out side peg
The hand grips are wrongly named.... should be hand rests..
look ahead.... if you look at that rut / hole you will end up in it..
hard pack ground weight forward rear wheel steer... soft ground weight back... light front wheel so it rides on the top not plowering .. go as fast as yer dare to stay on top..

thats it.... enough little gems of wisdom for one night...

...

Ariel Red Hunter · 12-16-2016, 11:57 AM

When I was big enough for a full size bicycle, my father found me a Rudge-Whitworth. Needless to say, like every kid with his first bike, I loved the thing. So what? do I hear? I was trolling through you tube when I ran into the Rudge Enthusiasts Club. Click goes my memory of my long ago bicycle. So I check it out only to find out that Rudge-Whitworth built some great motorcycles. TT winners in fact. And, being of mechanical bent, so to speak, I found that they built a 250cc class racer that anyone could buy nick-named the "radial valve wonder" and I was hooked. AND, even better, they offered super-sport model roadsters with the same engine in it! Of course you had to have pretty heavy coin in order to buy one, but of such things dreams were built. I guess if you were a Rudge dealer in those days, what are now called brochures were going out the door in an avalanche. But let's cut to the chase. All Rudges are pushrod over head valve jobs in their sport machines. Never made an overhead cam engine. The first of these engines came out in 1927, and the very few last ones were made in early 1939. Shifted over to war production, making whatever the war ministry told them to make. I was intrigued by the idea of a four overhead valve engine, with radial valves operated by two pushrods. How was this possible, I wondered. I was so fascinated by this whole concept, I had to join British e-bay in order to find a couple of pieces of paper that described this action, illustrated by a drawing that only sort of explains how this is even possible, let alone works. And between the cost of those two very old pieces of paper and the postage to get it into my hot, sweating little hands, it was an experience, let me tell you. How lucky we are to have the U. S. Postal Service in the USA let me tell you. So visualize a radial valve head. A hemispherical combustion chamber with four valves equally disposed in a circle, each portruding at a 45 degree angle to the valve chamber above the head. There are SIX rocker arms up there. I think. Could be eight. Can you imagine this? In another little pamphlet, obtained through the same ruinous financial manipulations as above, one of the engineers described the reasoning behind "The Mechanical Wonder of The Age" as the pamphlet described it. According to him, they were constrained by cost considerations to stick with push rod operated valves, and went with a four valve layout in order to get good breathing with light valve gear, so as to lower the loads on the push rods, so as to keep the pushrods as light as possible. OK, the interviewer asks, but why a radial layout rather than a pent-roof combustion chamber? Heat problems on the exhaust side caused head cracking. Head expansion in the exhaust valve area caused distortion, which also caused exhaust valves to loose their heads, which, of course is a calamity. This was with cast iron heads, of course. In the early 1930's, their foundry people came up with a way to blend aluminum with bronze to be able to cast bronze heads. Improved heat rejection, which allowed a higher compression ratio to be run. Now the Rudge was not a successful racer and TT winner in what used to be called the "Lightweight Class", but is now called 250cc class, just because it had a magnificent engine. Oh no, it had great brakes and handling and light weight to go along with it. You don't win on the Ilse of Man with just mucho horsepower. Now to cut to the chase. About 1934, using the aluminum-bronze head, they found that they could run a half pentroof-half hemisperical head. the half pentroof valves were in a line, while the exhaust were kept radial, for exhaust cooling purposes. Thus the "Semi-Radial Rudge". I wanted to see if it was possible to see one of these mechanical nightmares in action. And I found one video of a race in 2007(!) of a semi-radial Rudge in action. If you choose to watch this little video, note that the Rudges are running girder front forks, and what some folks call a "hard tail" frame vs other bikes, later ones, with modern front forks and swing arm frames. Have fun. Go to youtube Rudge Racing British Historic Racing 2007. Granted the guy can ride, but still!

12-02-2016, 08:29 PM	#241
pete Join Date: Jan 2012 Location: ChCh , NZ Posts: 2,261	[QUOTE=Ghenghis;2372 Some people dimpled their entire intake like the surface of a golf ball. Dimples on a golf ball are there to reduce it's wake as it moves through the air so they fly straight, a large wake causes irregular turbulence causing a sphere to change direction. Jury is out on that method, unsure if you'd see any difference over roughing up the intake surface, intake air isn't exactly moving around a sphere. I suppose you could dimple your choke plate... Keeping the heat in your exhaust flow results in a higher velocity which has a scavenging effect on the next exhaust cycle. Wrap those exhaust pipes and smooth out those burrs! I'm tired now.[/QUOTE] It's called the "Magnus effect"... only comes into play when the sphere is spinning.. is why a tennis soccer player or baseball pitcher can turn the ball in flight... it produces a low & high pressure area on opisite sides of the sphere .. high pressure side pushes the sphere into the low pressure side turning the sphere in flight.. also why muskets & canons had unrifled barrels to stop the musket ball spinning 'turning in flight" they used this force to power a ship... if intrerested google "flettener rotor" nature knows best..... sharks have a rough skin for this very reason it traps a thin layer of water that makes the shark very smooth & slipery.. exhuast wrap... hotter the exhuast gasses the thiner they are so they can travel faster... .... __________________ 09 XT660R ... 06 TTR250 ... 80 Montesa H6 125 Enduro... 77 Montesa Cota 348 MRR "Malcom Rathnell Replica"... Current resto projects.. 81 Honda CT110... 80 Kawasaki KL250A1... 11 Husaburg TE125 enduro... "sold" along with another 31... Lifan 125 Pitbike.. "stolen" ... KIWI BIKER FORUM...... http://www.kiwibiker.co.nz/forums/content.php All the best offroad rides in NZ... http://www.remotemoto.com/ E-mail... xtpete1@gmail.com
	0

12-06-2016, 05:56 PM	#246
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	Sweet running engines that never tire. I mentioned before sweet running, tireless engines. For may years, motorcycles were compared to horses, which is probably where that phrase comes from. A sweet motor cycle is one where the parts all seem to work in harmony. You don't have to think about what to do, it virtually seems to read your mind, and responds to your every thought. Maybe the modern phrase for this is fly-by-wire. Now I, and many others who grew up in the west, were born to the saddle. At least of my generation. I'd probably ridden four or five different horses before I rode one where I had that eureka moment of understanding how wonderful that experience could be. And once you have experienced it, you look for horses that you can develop that feeling of oneness with. Makes it easy to ride. And you can maintain higher average speeds with such a mount. Suprisingley, motor cycles are much the same. I'd ridden other motorcycles that I had never had that feeling of oneness with until I got my Red Hunter. I never had that feeling on a Harley-Davidson, but now that I'm thinking about this, that may explain the mystique of the Indian, it was that kind of bike. Japanese bikes I have owned were marvelous mechically, but never had that kind of soul. If you had ridden a Speed Twin, you were never all that impressed with to 450cc Honda twin. There was nothing really wrong with the 450, it was just not as sweet as the Triumph. As wonderful as the Yamaha 650 twin was, it was never in the class of a Triumph Thunderbird, or a BSA Super Rocket. They just lacked that fly-by-wire feel. The Hawk is a bike that approaches that hallowed ground. You have to manipulate a few things, but you can get there, if you want. So don't just drive it, ride it.
	2

12-06-2016, 09:46 PM	#247
BlackBike Join Date: Feb 2016 Location: George West, Texas Posts: 4,097	good one arh. __________________ ***************************************** 2015 Bashan"Blaze" BS250GY-31 (DB-07K-250) GONE 2017 Suzuki V Strom 650 XT "We are all born ignorant, but one must work hard to remain stupid." ~Benjamin Franklin~
	0

12-07-2016, 12:52 AM	#249
hertz9753 Join Date: May 2016 Location: Bismarck, ND Posts: 868	I thought you would enjoy that. __________________ 2015 and 3/4 RPS Hawk 250. Most people would call it a 2016 but the MCO didn't.
	1

12-10-2016, 01:15 PM	#251
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	Bikes I wished I had bought Yeah, but there is not a ton of them. I'll start with what is probably the most controversial: A K-model Harley Davidson. WHAT? Yeah, I know, flat head v-twin. But that is the problem with guys that read more into spec sheets than is really there. There are bikes that talk the talk, and then there are bikes that walk the walk. Kinda' ugly, stock. But what a street tracker you can build out of one of these. Bullet proof transmission. Bullet proof electrical system. Bullet proof clutch. Very tough engine. One of the first bikes with a swinging arm rear suspension. The first big bike with a unit power plant (engine and transmission in the same unit). Virtually unbreakable rear chain. Good handling, for the day. Fast enough for me. The handling was good because of the engine. Being a flathead, all of the weight was down low. The specs don't tell you that. That engine is infinately tuneable. ALL KR parts interchange. Oh, I forgot. Easy starting. Yeah, I wish I'd bought one. I have owned a Sportster, and I've ridden a couple of K's. The K was a superior bike in my opinion.
	0

12-03-2016, 01:30 PM	#243
Jmcgee Join Date: Sep 2016 Posts: 86	http://www.eastwood.com/images/email...ting_Guide.pdf Ariel, you are correct, I was reading this, it states you want about an 80 grit finish on the intake, and a polished exhaust.
	0

12-04-2016, 07:16 PM	#245
timcosby Join Date: Nov 2016 Location: robertsdale alabama usa Posts: 1,007	on a less serious note i was watching z nation the other night and the girl was riding what looked to be an older type hawk and if you watch real close the brake caliper switches sides of the wheel a couple times! to make the bike look like it was going in the right direction the editor had mirrored the scene which is like looking in a mirror. you could see the exhaust changed sides too.
	0

12-10-2016, 01:37 PM	#252
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	Next Next would be a Velocette MSS. Superb handling. Not fussy. Fast enough, though not really fast. Sort of a real symphonie of parts, made in a small factory, designed by two brothers who owned Veloce Limited. Everything about it contributed to the whole. I had a chance to buy one for short money, but I was tap city at the time. Next, a Bultaco Matador - and I don't even like two-strokes. Another machine made in a small factory in which all the parts all together made a superb whole. Oh yes, a 500cc Cotton. Just because they were so uniquilley beautiful, AND it had a fire breathing J.A.P engine. Light. Superb handling. Lycette saddle. Girder forks. Made in small numbers from 1929 to 1948. Really doesn't look like I missed out on much, does it.
	0

12-13-2016, 01:46 PM	#253
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	The Hawk And it's many brothers and sisters that use the same engine. Luckily for short money guys (like me), foundry technique had progressed to the point to when these engines were first built they already had superb head castings in mass production. Die cast aluminum heads started in the 1930's with radial aircraft engines. You can see, perhaps, the advantage of die cast heads from a production standpoint of engines that required 7 or 9 or 14 or 18 or even more identical heads per engine. By the time WW11 rolled around, die cast heads were in common use. And these were 2nd or 3rd generation heads. Which meant that the intake and exhaust ports were much more sophisticated. The big time manufacturers of the radial engine were Wright, Pratt & Whitney in the US, Bristol in England, and BMW in Germany. Not to forget radials used in Zeros in Japan. So, from this experience came the first die cast heads for motorcycles in the early 1950's in England and Germany. It took 2 or three generations of making die-cast heads in the MC Industry to really get the porting right. Honda did a superb job of designing heads by the sixties and beyond. So the head on the Hawk was perhaps a fifth generation design. And these heads are superb. That's why I'm not in favor of doing port work on them. From the mid-fifties on, virtually every engine design department did a lot of flow bench work on each new generation head. The beauty of die casting is, once you have something that really works, you can re-produce this in the millions. And the engine used in the Hawk is the beneficiary of this outstanding head design. Now, when some manufacturer has a frame and chassis he wants an engine for, they have a tendency to not understand the interplay between the intake system, the head and the exhaust system. Or, in engineering terminology, the effect of the interplay of these issuus on B.M.E.P.. Brake Mean Effective Pressure. How do you get more BMEP? Reduce to the minimum air flow restrictions on the intake side, and do everything you can to improve exhaust flow, and jet the carburetor accordingly. Next, if you want to spent the money, more compression ratio. The cam used in this engine is more than adequete to do the job. After all, the engine spins right on up to ignition cut off speed, so getting adequete cylinder filling at high rpm is not the problem, the problem is to get more bang for the buck, ie better BMEP, so you get some more bang per firing shot. Focus on this, and you will be sucessfull.
	1

12-16-2016, 11:57 AM	#255
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	Ah, how sweet it is When I was big enough for a full size bicycle, my father found me a Rudge-Whitworth. Needless to say, like every kid with his first bike, I loved the thing. So what? do I hear? I was trolling through you tube when I ran into the Rudge Enthusiasts Club. Click goes my memory of my long ago bicycle. So I check it out only to find out that Rudge-Whitworth built some great motorcycles. TT winners in fact. And, being of mechanical bent, so to speak, I found that they built a 250cc class racer that anyone could buy nick-named the "radial valve wonder" and I was hooked. AND, even better, they offered super-sport model roadsters with the same engine in it! Of course you had to have pretty heavy coin in order to buy one, but of such things dreams were built. I guess if you were a Rudge dealer in those days, what are now called brochures were going out the door in an avalanche. But let's cut to the chase. All Rudges are pushrod over head valve jobs in their sport machines. Never made an overhead cam engine. The first of these engines came out in 1927, and the very few last ones were made in early 1939. Shifted over to war production, making whatever the war ministry told them to make. I was intrigued by the idea of a four overhead valve engine, with radial valves operated by two pushrods. How was this possible, I wondered. I was so fascinated by this whole concept, I had to join British e-bay in order to find a couple of pieces of paper that described this action, illustrated by a drawing that only sort of explains how this is even possible, let alone works. And between the cost of those two very old pieces of paper and the postage to get it into my hot, sweating little hands, it was an experience, let me tell you. How lucky we are to have the U. S. Postal Service in the USA let me tell you. So visualize a radial valve head. A hemispherical combustion chamber with four valves equally disposed in a circle, each portruding at a 45 degree angle to the valve chamber above the head. There are SIX rocker arms up there. I think. Could be eight. Can you imagine this? In another little pamphlet, obtained through the same ruinous financial manipulations as above, one of the engineers described the reasoning behind "The Mechanical Wonder of The Age" as the pamphlet described it. According to him, they were constrained by cost considerations to stick with push rod operated valves, and went with a four valve layout in order to get good breathing with light valve gear, so as to lower the loads on the push rods, so as to keep the pushrods as light as possible. OK, the interviewer asks, but why a radial layout rather than a pent-roof combustion chamber? Heat problems on the exhaust side caused head cracking. Head expansion in the exhaust valve area caused distortion, which also caused exhaust valves to loose their heads, which, of course is a calamity. This was with cast iron heads, of course. In the early 1930's, their foundry people came up with a way to blend aluminum with bronze to be able to cast bronze heads. Improved heat rejection, which allowed a higher compression ratio to be run. Now the Rudge was not a successful racer and TT winner in what used to be called the "Lightweight Class", but is now called 250cc class, just because it had a magnificent engine. Oh no, it had great brakes and handling and light weight to go along with it. You don't win on the Ilse of Man with just mucho horsepower. Now to cut to the chase. About 1934, using the aluminum-bronze head, they found that they could run a half pentroof-half hemisperical head. the half pentroof valves were in a line, while the exhaust were kept radial, for exhaust cooling purposes. Thus the "Semi-Radial Rudge". I wanted to see if it was possible to see one of these mechanical nightmares in action. And I found one video of a race in 2007(!) of a semi-radial Rudge in action. If you choose to watch this little video, note that the Rudges are running girder front forks, and what some folks call a "hard tail" frame vs other bikes, later ones, with modern front forks and swing arm frames. Have fun. Go to youtube Rudge Racing British Historic Racing 2007. Granted the guy can ride, but still!
	1