Hawk Talk

[Megadan]

If we used the basic principle of power vs. drag, which is roughly a factor of 4, (4 times the power to go double the speed) then if we took a stock Hawk that can reach 60mph with roughly 15hp, it would take about another 7-8hp for that same bike to reach 75mph.

Yes, there are way too many factors I left out, but the basic principle holds. If a Hawk has roughly 15-16hp and can reach 62mph (my own experience) then it would take about 22hp for that same bike, under the same conditions, to reach a max top speed of 75. I will note that I am going off of repeatable speeds, not my own personal best where I hit 65 a couple of times when stock, but it was rare.

So, with the right rider and conditions, 80mph isn't entirely unrealistic for a Hawk with head work and supporting mods. At that point it will really come down to the gearing. I know that you and I are both using a similar gear ratio of around 2.5:1, which will max out at 80mph at around 8000rpm.

[Ariel Red Hunter]

Originally Posted by JerryHawk250

Azhule is already running 80+ mph. Can only get faster.

I should hope so, I bought that model 14 AJS 250 new in 1963...ARH

[Ariel Red Hunter]

For a magneto to operate at peak voltages. it has to be within what is called 'The E-gap'. Yeah, but they've used magneto ignition since the day the spark plug was invented, someone is bound to say. Well, no. They had magneto ignition even before the spark plug was invented. It was called 'Make and Break' ignition. Anyway, the thing with magneto ignition is that the spark must be initiated during this e-gap period, or a weak spark will result. So there is a very limited arc of degrees available to give good ignition. But variable ignition control would be the next step in the climb of rpm (and horsepower). So some magneto's were made that could be rotated in their mounts in order to advance timing while still having that oh-so-important e-gap occur when needed. Eventually they found a way to advance the ignition internally in the magneto by moving the coils a short distance around the rotor. But the ignition system used in the Hawk has no way to advance the spark, or retard it, because the coils are mounted tightly to the engine. So the ignition timing is determined at the factory, and is set so as to permit starting, and from idle speed on up the engine has to be satisfied with sub-optimal timing. To get maximum power out of this engine we will have to figure out a way to get variable ignition timing. The simplest way might be an impulse coupling built into the rotor. Faibanks-Morse mags were built that way for years. The impulse coupling retarded the ignition for a full shot of juice at cranking speed, then at about 500 rpm a governor released the spring controlled impulse coupling and the ignition timing went from 0 advance to 34 degrees advance faster than the blink of an eye. Not perfect but better than what we've got now...ARH

[Ariel Red Hunter]

The geese have started flying north, so maybe spring is going to show up after all! So folks have been buying new motorcycles. And for many of them it will be a new China bike. And with most China bikes come carburators. And, in order to sell these in the United States they have to be EPA compliant. And that means ultra lean. And very short gearing with a rev limiter to prevent over heating. And that's just on the intake side. The exhaust side is a whole additional chapter, which we won't go into now. The carburetors used on Hawks are all the same, design wise. They all can be made to work. But with varying degrees of difficulties. The least difficult is the Mikuni, the most difficult is the Sheng Wei, and the Keihin is in the middle. This is because the Sheng Wei body has to be re-machined in order to accept interchangeable pilot jets. The Keihin has after-market jets available, sometimes made by Uncle Pooties Plow Works. The Mikuni has very carefully made factory jets, both main and pilot/slow available. Mikuni also has various throttle slides and needles available as well, so it is much more tune-able. But you will have to decide how much of all of this you need. If you are primarily a street rider, a main jet change, a shimmed needle. and an over rich idle fuel setting will get you by. If you really like off roading, you really need something more tune-able. That's where the Mikuni comes in...ARH

[Ariel Red Hunter]

There have been a rash of wheel bearing failures it seems this year. Could be a quality control problem at the vender who the bike manufacturer buys the bearings from. But just as likely is failure of the grease in the bearing itself. These bikes can have a hard time of it getting over here. They come by the container load. I suppose all of you have seen pictures of container ships, with many containers going as deck cargo. Imagine that ship leaving China and coming across the Pacific, going to New Orleans, or Houston to unload. Do you really think the weather was perfect all of the way? If that ship went through more than average temperature fluctuation coming here, there will be plenty of condensing in those bearings. Chinese grease has not had a good reputation at protecting bearings from water. If a ship comes through more than the normal number of storms there can be so much condense in those bearings, that the bearing tracks can rust right where the



balls or rollers are sitting. The life of that bearing is severely compromised. If one of the wheel bearings fails, immediatly replace all of the wheel bearings, and CLEAN AND REPACK THE STEERING HEAD bearings without fail...ARH

[Ariel Red Hunter]

Tires are your choice, of course. And not only the tread pattern, but also the sizeing. Depending on your anticipated usage of the bike. There are three definative types, and one kinda' on the fence between two of the other types. Knobbies, Trials, and street tires. And the fence sitter, Dual-Sport. Nothing wrong with dual sport tires. Really, those are the kind of bikes we are talking about. Right? The Hawk comes with knobbies, which are a bit extreme for the kind of riding most people do. Not to mention a little squirrely on paved roads. My personal choice would be Pirelli MT 43's for my potential uses, a trials tire whice throws mud really well, yet is very good on pavement, and last a long time. There are other traditional trials tires that cost less from Asia. Kenda is one of them. Street tires cannot be beat for street usage. Especially for people who grind their footpegs on the pavement going through corners. Now to sizeing. My semi-educated guess is, on street tires and dual-sport tires put the widest ones on that don't interfere with the chain, or exceed recommended width for the rim size. 4.10 is stock rear, I think 4.60 is the largest recommended. For my uses, here on the north slope of the Adirondacks, I'd use Pirelli MT43's because (a, I've got to ride 25 miles of blacktop to get to my off highway jumping off point at St Regis Falls, NY. (b, it is more socially responsible to not tear the terrain to shreds, and/or raise the snowflakes level of general un-pleasantness to full foam-at-the-mouth death threats. I know that big gnarly knobs are like totally awesome (dudes!) and so neat to roost your buddies with, AND AT THE SAME TIME dig trenches you can lay pipe in, but not deep enough to get below the frost line. Rant over.

[Ariel Red Hunter]

Yes, Mikuni's are the best carb upgrade you can make. Yes, I know that they are "All Basically the Same". So what? It is how they are NOT all the same that matters. Yeah, I'm gonna lay it all out for you, and pull no punches. Many years ago, Mikuni took over from Amal the mantle of "THE high performance motorcycle carburetor" from Amal. Amal wasn't out-engineered, they lost their way during the British motorcycle industries death spiral into insignifigence in the 1960's. The Amal Concentric is the direct ancester of all Asian round-slide carburetors. All of them, the good (Mikuni), the bad (Sheng-Wei), and the indifferent (Keihin). That doesn't mean that they all don't work, they all do if you don't change anything. In my barely humble opinion, if you don't want to buy a Mikuni, save your money and don't buy anything. This is even true of square slide jobby-dues as well. Truthfully, Mikuni has forgotten more about carb tuning than anyone else ever knew. Except Amal. Not the company, but the stacks of research papers and tuning manuals from the 1920's to the 1970's.
I used to tune carburetors for what I laughingly called a living. Assuming the casting and machining are satisfactory, we're on our way. First thing we need is absolutly accurate jets, and where better to get them than the original manufacturer. I know Genuine Mikuni jets cost more than those made by Uncle Pooties Plow Works, but believe me Mikuni's are much more accuratly made, and easy to get. Easy to get is very important. Five groove needle adjustment is another plus. Pilot jets made to the same standard sure saves a lot of aggravation and language that should NOT be heard by ladies and little children. And now we get to the last advantage; interchangeable throttle slides. Only Mikuni offers this. The more the slide cut-away the less accelerator pump effect you get, the less cut-away the more accel pump effect.

On a bike used on the street and the trail, I set the needle in the middle slot, then turn the idle mixture screw open 1 1/2 turns and change pilot jets until I get a strong idle. I set the idle speed somewhere in the 1250-1450 range where the engine is happy. You set the idle rpm with the idle speed screw on the side of the carb. I expect the machine to carry carry me along a level hard road in first gear with my hand off the twist grip without stalling. When I've got the pilot jet that gets that job done, then I crack the throttle about a quarter turn. If I get a couple of hard thumps, all is well. If it is at all weak, I go to a throttle slide with less cut-away. I am sure all of you know how to deal with the main jet....ARH

[ChrisWNY]

Originally Posted by Ariel Red Hunter

There have been a rash of wheel bearing failures it seems this year. Could be a quality control problem at the vender who the bike manufacturer buys the bearings from. But just as likely is failure of the grease in the bearing itself. These bikes can have a hard time of it getting over here. They come by the container load. I suppose all of you have seen pictures of container ships, with many containers going as deck cargo. Imagine that ship leaving China and coming across the Pacific, going to New Orleans, or Houston to unload. Do you really think the weather was perfect all of the way? If that ship went through more than average temperature fluctuation coming here, there will be plenty of condensing in those bearings. Chinese grease has not had a good reputation at protecting bearings from water. If a ship comes through more than the normal number of storms there can be so much condense in those bearings, that the bearing tracks can rust right where the



balls or rollers are sitting. The life of that bearing is severely compromised. If one of the wheel bearings fails, immediatly replace all of the wheel bearings, and CLEAN AND REPACK THE STEERING HEAD bearings without fail...ARH

Gotta grease 'em good during assembly of the bike. It's especially important to grease those axles as well as the bolt that goes through the rear monoshock. I used Mobil 1 synthetic grease on any bushing/bearing that I could get at during assembly, so far it seems to be doing very well.



That's interesting about the condensation causing issues in the bearings. Unfortunately there probably isn't much if any QA/QC on these bikes before they're shipped, that's why they're less than 1/5th the cost of a comparable Japanese equivalent.

[pete]

Originally Posted by Ariel Red Hunter

For a magneto to operate at peak voltages. it has to be within what is called 'The E-gap'. Yeah, but they've used magneto ignition since the day the spark plug was invented, someone is bound to say. Well, no. They had magneto ignition even before the spark plug was invented. It was called 'Make and Break' ignition. Anyway, the thing with magneto ignition is that the spark must be initiated during this e-gap period, or a weak spark will result. So there is a very limited arc of degrees available to give good ignition. But variable ignition control would be the next step in the climb of rpm (and horsepower). So some magneto's were made that could be rotated in their mounts in order to advance timing while still having that oh-so-important e-gap occur when needed. Eventually they found a way to advance the ignition internally in the magneto by moving the coils a short distance around the rotor. But the ignition system used in the Hawk has no way to advance the spark, or retard it, because the coils are mounted tightly to the engine. So the ignition timing is determined at the factory, and is set so as to permit starting, and from idle speed on up the engine has to be satisfied with sub-optimal timing. To get maximum power out of this engine we will have to figure out a way to get variable ignition timing. The simplest way might be an impulse coupling built into the rotor. Faibanks-Morse mags were built that way for years. The impulse coupling retarded the ignition for a full shot of juice at cranking speed, then at about 500 rpm a governor released the spring controlled impulse coupling and the ignition timing went from 0 advance to 34 degrees advance faster than the blink of an eye. Not perfect but better than what we've got now...ARH

The CDI has the advance built into it.... it detects the time delay between the pulses from the motor and knows the revs the motor is doing then advances the spark to suit those revs...

[pete]

I know that little blob of grease in a bearing looks silly and well under what it should have..
but that little blob of greasse has had millons of dollars and hundreds of hours of testing
to work out the size of that little blob..

grease in the bearing produces friction as well as lube it...
the friction is required to make the balls roll if there was no friction the
balls would skid around the races... if you put too much grease in the
friction is to much and again the balls skid instead of rolling...

another thing is the inner and outer rases have diffent dias so the balls
can not roll around both race at the same time so there is ball skid
in the bearing anyway so the last thing you want is to add more...

you can add more grease.. but just don't pack them solid with grease..



...

[Megadan]

Originally Posted by pete

I know that little blob of grease in a bearing looks silly and well under what it should have..
but that little blob of greasse has had millons of dollars and hundreds of hours of testing
to work out the size of that little blob..

grease in the bearing produces friction as well as lube it...
the friction is required to make the balls roll if there was no friction the
balls would skid around the races... if you put too much grease in the
friction is to much and again the balls skid instead of rolling...

another thing is the inner and outer rases have diffent dias so the balls
can not roll around both race at the same time so there is ball skid
in the bearing anyway so the last thing you want is to add more...

you can add more grease.. but just don't pack them solid with grease..



...

I think the proper term for the grease isn't friction, but resistance. Too much grease can create hydraulic resistance. Grease alters the coefficient of friction between the rollers and the races by reducing it, which in the worlds of resistance, steel on steel is also a very low friction affair. The addition of lubrication actually decreases that friction as well as acting like a thermal stabilizer by helping to prevent hot spots and spreading the heat out more evenly. The inverse of adding that grease to a sealed system is that there is less air and more of a highly viscous fluid. This fluid creates resistance in the bearing, which is why brand new bearings roll freely, but have a stiff feeling to them.

As they are run and heat up the grease will break down as well as be spread more evenly. As it gets hot and/or breaks down over time it gets thinner, and over time the seals stop sealing and it seeps past the seals and eventually runs dry.

Too much grease in a bearing will cause the grease to expand and possibly force past the seals or in extreme cases the seals can "burst" open. Too little grease and the bearings life is greatly reduced.

So there is definitely a calculated amount of grease that goes into a sealed bearing. They need to strike a balance between lubrication, reliability/lifespan, and cost.

Other factors that can also be adjusted for those lifespans is diffrent types of seals, different alloys in the races and rollers, cage design, rows of rollers, and even types, sizes, or shapes of those rollers.

My 2 cents when it comes to the wheel bearings on these bikes - they suck. New high quality bearings with better materials and seals are inexpensive in the grand scheme of things. You can obviously try to expand the life of them, but for $20 they can simply be replaced with something of a far superior quality that will last 5 to 10 times longer in the same conditions.

[Ariel Red Hunter]

Originally Posted by ChrisWNY

Gotta grease 'em good during assembly of the bike. It's especially important to grease those axles as well as the bolt that goes through the rear monoshock. I used Mobil 1 synthetic grease on any bushing/bearing that I could get at during assembly, so far it seems to be doing very well.



That's interesting about the condensation causing issues in the bearings. Unfortunately there probably isn't much if any QA/QC on these bikes before they're shipped, that's why they're less than 1/5th the cost of a comparable Japanese equivalent.

That's not a theory about condensation causing roller bearing failure. At International Harvestor we had this problem come up. Mother Harvestor would rectify manufacturing defects for years after the original warranty ran out. We started getting a lot of transmission and final drive roller bearing failures. We wanted to know why. It had become the fashion among Illinois CBF farmers (Corn Beans Florida) to build all metal machinery storage buildings. On a sunny winter day the temperature would go from 10 or 15 above to 40 or 50 above. I remember walking into one of these buildings about 10:00 am and it was almost raining in there. Then it would freeze again at night...ARH

[Ariel Red Hunter]

There is an easy way to check your main jet mixture. Much easier for most people than reading a spark plug. First ride the bike for at least 20 minutes so the engine stabilizes its temperature. Get on a 55 mph road with virtually no traffic. Get the bike up into the high gear range, well up the rpm scale, but not all the way to maxxed out. Now, just back off the throttle about 1/8th turn. If the fuel mixture is too lean you will feel a mini surge in power, just for an instant. If it is right it will be fine. If it feels boggy when you open up again, it is too rich. Repeat several times to make sure you are correct...ARH..

[Ariel Red Hunter]

Originally Posted by Ariel Red Hunter

I haven't bought a Hawk. I am getting close to 80 years old. I'm not sure a motorcycle is a good idea at my age. What I type up here is a production engineers view of them. I hunt for information on stuff, then analyze it. You are reading the results of my studies. And the results of my experience. I've been riding since 1951. But I will tell you this; if I was going to buy a motorcycle this year, it would be a HAWK!!

Hey, Audihuff. Good to dee you doing research!...ARH

[Hawk'em]

Has anyone replaced the shift shaft seal on the hawk mine has 200 miles on it and has started leaking