Hawk Talk

[pete]

Originally Posted by Ariel Red Hunter

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?

you do know ?....
yamaha have been making 5 valve radial heads for over 20 years ....
3 inlet valves / 2 exhust valves...
Honda had radial 4 valve heads in there 2nd genaration XR 250 and up...


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[Ariel Red Hunter]

Originally Posted by pete

you do know ?....
yamaha have been making 5 valve radial heads for over 20 years ....
3 inlet valves / 2 exhust valves...
Honda had radial 4 valve heads in there 2nd genaration XR 250 and up...


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Yes, I do know. But as far as I know, neither Honda nor Yamaha had them available for sale between 1927 and 1939.

[hertz9753]

Originally Posted by pete

you do know ?....
yamaha have been making 5 valve radial heads for over 20 years ....
3 inlet valves / 2 exhust valves...
Honda had radial 4 valve heads in there 2nd genaration XR 250 and up...


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Those bikes used the dual exhaust headers into single muffler.

[Ariel Red Hunter]

Did any body watch that video that I put in there? What do yo think of that almost pre-historic Rudge Semi-Radial Valve lay an ass-whipping on that bevel drive Ducati? How Sweet It Is!

[Ariel Red Hunter]

Yeah, and I know - "Why should I care." But first, I was hoping that some of you would have watched that race, and thought, wow maybe pushrod engines are not all slugs. And neither is the engine in the Hawk and other CB bikes that use this engine. This engine can be tuned to give great results, although I think water-cooled engines can make more power. Trouble is, water-cooled usually require water pumps and radiators. So they are going to be not only be heavier, but the added weight is in the wrong place. Up high. Usually just below the headstock. From what I have seen, manufacturers go to lengths to lower total weight with aluminum frames, or exotic frame materials. This costs a bunch of money, along with the engine components required to make a water-cooled bike practical, never mind the ultimate list price. If you watched that video, perhaps it occured to you that a well developed pushrod air-cooled engine still has advantages in real world uses. And, at least to me, this little engine in the Hawk, and others, is a real useful tool in designing a light-weight on/off road machine. But the Hawk is designed for what used to be called "The colonial market." Which means much more weight in the frame and suspension and attachments then is really needed for our uses. Heck, even the stock exhaust system is much heavier then what is available on the secondary market. Getting some of that heavy stuff off of the bike will have the same effect as adding horsepower. If you do both, you are ahead of the game. And Roland Pike was the man who took this little Rudge to the next performance level. A Roland Pike Rudge was much faster than the Rudge you saw in the video, if you checked it out. In fact, they became known as Pike Rudges because not only were they much faster then the factory Rudges, but he was the leading rider in the 250cc class until 1954. What happened in 1954? BSA was so impressed with what he had done with the Rudge, they hired him to breath new life into the BSA Goldstar - and he was sucessful.

[Ariel Red Hunter]

A while back I made the comment that it is a lot easier to design an overhead cam engine than it is to design a free revving push rod motor. There are all kinds of little nuances in the design of a push rod system to make it competitive to a OHC job. But it can be done. A short list; Rudge 250's. Harley-Davidson Aermacchi 250's, AJS model 14 250's, Moto Parilla 250's. Motobi 250's. Hawk (and other makes that use the same engine) so-called 250's (actually 229cc). BSA Goldstar 350's and 500's. There are more, but maybe you get the idea. I suppose that none of you have ever rode a BSA C-15 or B-25, and their ilk, but I have, and easy running is not a word that I would use to describe them. They have their good points, and they are kind of nice, but they sit pretty far in the shade compared to the others, rev wise. And every one of those little buggers that were easy running never tired. They could run all day, every day, at high r.p.m. and never turn a hair. I had owned a BSA C-15 and raced it in the TT races in California. Then, one day I stopped by the Cooper Motor Co. in Southern California one day, and they had a AJS Model 14 on the show room floor. After listening to the usual sales pitch, I went back in the shop, and talked to one of the tuner/mechanics. I asked him if he had ridden one and he lit up like a thousand watt light bulb. Oh yeah, he said. Think "Pocket Rocket". So a couple of weeks (maybe a month) later I had sold my C-15, and bought the little AJS. And that's just what the guy had said. Pocket rocket fit it very well. Now the layout of that little AJS engine was almost egzactly the same as the engine in the Hawk. A short pushrod big bore, short stroke 250. With a similar valve operating mechanism. Better carb and exhaust system than the Hawk has, but we can take care of that, right? Those little Ajays were pulling 22-24 hp on the bench. Now understand that that little ajay was not a unit construction engine, so you have to deduct 9 or 10 percent to compare it to a gear drive primary, like on the Hawk, Ajays had a chain primary drive. More efficient. So the Hawk is potentially capable of generating 20-22 hp, on the bench. Oh yeah, just like the Hawk, it had a very wide power range, so it was not a fussy high rpm only engine.

[Ariel Red Hunter]

Yes, I know, spokes have been talked ad finitum on this forum. But not lately. So, you need a spoke wrench. And you need to keep those spokes evenly tight all around the wheel. All that you really need to know about this thingy is this: Go around the wheel and "ping" every spoke. If they are all at middle "C" (on a piano), or not higher pitch than one octave higher in the scale, and are all even, you are good to go. You have to keep after this on a China bike because they use pretty thin spokes, and they stretch with use. If you have to tighten them, start at the valve stem and tighten every 3rd spoke. Then go around again doing the next set of spokes. Then the last set. In other words, you tighten 12 spokes on each go-round. If this is not clear, let me know. Sincerely, ARH

[OUTERLIMITS]

Originally Posted by Ariel Red Hunter

Yes, I know, spokes have been talked ad finitum on this forum. But not lately. So, you need a spoke wrench. And you need to keep those spokes evenly tight all around the wheel. All that you really need to know about this thingy is this: Go around the wheel and "ping" every spoke. If they are all at middle "C" (on a piano), or not higher pitch than one octave higher in the scale, and are all even, you are good to go. You have to keep after this on a China bike because they use pretty thin spokes, and they stretch with use. If you have to tighten them, start at the valve stem and tighten every 3rd spoke. Then go around again doing the next set of spokes. Then the last set. In other words, you tighten 12 spokes on each go-round. If this is not clear, let me know. Sincerely, ARH

That is a very good method to tighten spokes

[timcosby]

Originally Posted by Ariel Red Hunter

Yes, I know, spokes have been talked ad finitum on this forum. But not lately. So, you need a spoke wrench. And you need to keep those spokes evenly tight all around the wheel. All that you really need to know about this thingy is this: Go around the wheel and "ping" every spoke. If they are all at middle "C" (on a piano), or not higher pitch than one octave higher in the scale, and are all even, you are good to go. You have to keep after this on a China bike because they use pretty thin spokes, and they stretch with use. If you have to tighten them, start at the valve stem and tighten every 3rd spoke. Then go around again doing the next set of spokes. Then the last set. In other words, you tighten 12 spokes on each go-round. If this is not clear, let me know. Sincerely, ARH

an octive is 12 notes higher on a guitar so lets not go that high i think you meant one note above the c maybe

[Ariel Red Hunter]

Originally Posted by timcosby

an octive is 12 notes higher on a guitar so lets not go that high i think you meant one note above the c maybe

My attitude probably comes from the fact I play (A) by ear, and (B) my weapon of choice is a cornet. I was invited to play in a jazz band one time, and the guy says how do you like to play. And I said I really only hit two notes, C and G. He looked at me kinda funny, so I said " Like this," and ran from low B flat up to E above high C. He laughed, and said, "You got me". No, I said, those other notes are just variations on C and G, to me. The other notes are just valved or lipped. I have never heard such a fairy tale in my life he said. I laughed. So yeah, middle C to the next higher G, that range is easy to differentiate, in your ear. That's only four whole notes (naturals, some call them). No need to go all the way to go to the C above middle C on the piano keyboard, like you said

[Ariel Red Hunter]

Yes, cables can be very annoying and can cause mucho problems on any bike. And, what if: a manufacturer can save 3 cents (American) per cable by making then as short as possible, AND makes, oh say a hundred thousand motorcycles a year. Six cents a bike. Times a hundred thousand bikes equals, if my math is correct, $6000.00. Personally, an extra six grand a year would fit very well in my wallet. And then add how much cheaper they are buying cables at the lowest rung on the ladder of acceptable quality, and you are saving maybe $2.00 per bike. You can buy do-it-yourself cable kits of much higher quality on e-bay. And learning how to make your own cables is an awful good thing to know. Of course, these are still not at the quality level of what is used on Harley-Davidson's, but not to worry, no one else except Indian and other American manufacturers used cables that good. British cables were excellent. But were more squishy and not as long lived as those H-D cables. John Mac Laughlin had a front brake cable failure during the FIM Grand Prix at Willow Springs, Calif on a Norton Manx. I told him after the race to change to H-D cables, even if you have to modify the brake lever and the brake cam lever to accept them. He said "Where were you last week with this information"? We both had a laugh at that. He was racing against Mike Hailwood and Paddy Driver in that race and had probably had never had to use his brakes that hard before.
Anyway, pull the tank off, and make doubly sure those cables run free and easy no matter which way the handle bars are pointing. Lubricating the cables helps a bunch, too. And I learned many years ago, pounding across the Mojave Desert, having pre routed spare cables for the clutch and throttle cables is a really good idea.

[pete]

I always carry spare throttle cables on the XT if i'm going
away for a few days ride... clutch is not a issue with
the rekluse clutch... works fine with out the manual
clutch oparation... just have to turn the motor off
to get it in to nutrual...


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[Ariel Red Hunter]

In order to draw fuel from the float bowl during starting, especially when the engine is warm, only open the throttle no more than 1/8th open. This is neccesary because having the throttle in this position causes a depression in the pilot circuit. This causes the fuel to flow into the carburetor venturi. When you open the throttle much past this point, there is insufficient vacuum to lift the fuel from the float bowl to get a correct amount of fuel to air mixture ratio to get the engine running. The only reason to use a lot of throttle to start the engine is if you flooded it. Sincerely, ARH

[Ariel Red Hunter]

To get into the steering head bearings. Ideally, we would clean and re-grease the bearings as part of the machine set-up process. But it is pretty easy to go into information overload on this issue. There are quite a few steps to go through with the steering head bearing improvements situation. Yes, this is a warning. But it is winter time most everywhere, you are used to the bike, maybe you've tuned the carburetor, changed the exhaust system, and modded the air cleaner box. So let me caution you on this before you even think about laying a wrench on it. These bearings are what is called "cup-and-cone" bearings. That means there is a cup, a cone, and a healthy handful of little ball bearings. The real trick is to keep these little ball bearings from cascading all over the garage floor while you are taking it apart. If you are not sure of this, get ahold of a junk bicycle that still has the forks on it. Undo the lock nut while holding the adjusting nut in place. Wrap the lower part of the head stock with a rag. This is to catch any little steel balls that seem to be magically attracted to every dark, dirty corner of your garage. Hold the fork up while you remove the adjusting nut. Very gently and carefully, lower the fork from the stemhead. If you are careful, you will not disturb the top bearing. Oh yeah, you did remember to take off the handle bars first, right? I made a little tool to fish the top bearing out complete. I went the hardware store and looked around until I found a little masonry tool that had folding wings on one end, and a screw and nut on the other. To this I added a washer big enough to almost cover the top part of the bearing. Then I just lifted the whole thing out of the stem head, and put it into a Gerber's baby food jar. That was to make sure I didn't lose any ball bearings. That way I knew how many balls were supposed to go in the bottom too. A motorcycle is a little different, obviously. It has a top clamp. So you have to remove the handle bars, the top clamp, the lock nut, and the bearing adjustment nut. But from there on, it's the same thing, only bigger.

[Ariel Red Hunter]

As part of our efforts to get the maximum air-fuel mixture into the combustion chamber on each intake stroke, we need to reduce any and all situations that disrupt the air flow to the carburetor. Opening up the air-box comes first to mind. Then, maybe, we wonder, do we need an air-box at all. And the answer is; yes and no. Do I hear, Jeez ARH, can't anything be simple? If you live where it is dry, a pod filter works just fine. But in the rest of the United States, an air-box has advantages. The original idea behind an air-box was to provide still air to the carburetor, and to protect the filter from splashed water getting to the dry paper filter. The air-box works pretty well for this. It also has great advantages in sandy terrain. You coat the interior of the air-box with chassis grease, about an eighth of an inch thick to trap the sand that is getting into the air-box. Did I dream that trick up? No. I learned about it from Jeff Smith, the World Champion MX'er on BSA Victor 441's. Let me tell you of a couple charming features of the Victor 441. Feature number one was its eagerness to toss you over the handle bars when attempting to start the little beastie, and feature number two was its desire to hoist its front wheel skywards every time you gave it just a little too much gas. One guy who rode one told me it would wheelie so fast, you didn't have time to bail off, but would end up on your back, with your hands still on the hand grips, and feet on the foot pegs, "looking like a turtle that had been flipped on its back". I am semi-sure that was an egzaduration. Semi-sure. Why ride it then, I asked him. Because it is FAST. What pain, and aggravation we go through to pay homage to the Gods of Speed. One of the hot store bought MXers of the day was the Yamaha 360 two stroke. That 441 would clean its plow, if you were man enough to ride it.