Hawk Talk

[hertz9753]

Originally Posted by Ariel Red Hunter

That was after I left the motorcycle racing scene the first time. Andy's rider on his Gold Star was Preston Petty.

I put a Preston Petty black fender on the front of my 1974 Yamaha GT80. I think I ordered it from JC Whitney, but I still couldn't keep up with the Honda XR75's.

[Ariel Red Hunter]

Originally Posted by hertz9753

I put a Preston Petty black fender on the front of my 1974 Yamaha GT80. I think I ordered it from JC Whitney, but I still couldn't keep up with the Honda XR75's.

Yeah, but in your mind it turned that GT80 into a rocket ship.

[Ariel Red Hunter]

At that time, I had somehow gotten the possesion of a 350 AJS, popularly known as an "Ajay". I ran that bike on SoCals idea of TT races. A dirt road track with a jump. Right and left turns. A miniature road racing track on dirt, in other words. The engine was not as free revving or as powerful as the Ariel, but the suspension was much better. I finally got around to going to Cooper Motors, the west coast importer of AMC motor cycles (James, Francis-Barnett, AJS, Matchless, and Norton), in and out a few times, buying stuff like oil filters (a felt cartridge that fit in the oil tank on the return side) , carburetor jets, and so on, getting acquainted with the guys that worked there. You guys surely know that technique. Pretty soon I got to go back in the shop, and exchange a few words with one of the mechanics. See, you had to know your way through the parts list to find the real goodies. And then would be revealed the greatest secret of all - - - there was ANOTHER parts list with all the factory racing goodies on it. Top secret shit! My tongue was hanging out! I noticed a special scrambles head for AJS/Matchless scramblers. Expensive. I asked about getting one. Oh no, can't be done. For factory supported racers only. Luckily, I had the short stroke engine. Mechanic suggested that I take my head to Jerry Branch, who had a flow bench, and would get out of that head every thing possible. I waited a couple of weeks (next paycheck) to take the head to Jerry. I'd been by his shop to enquire about this, and he said sure, bring it by. So I did, and picked it up a week later. He said you should be happier now, this head was really constipated on the exhaust side. Learn something new every day, right? Put the new head on, and engine came to life. Over the next winter, bought scrambles cams, and a little better top end. I was doing pretty well until one of the other guys bought a Gold Star 350. Partly he was a better rider than I was, and partly that Gold Star was a better engine. See a trend here? About this time, Andy Kolbe was working at night in the shop (He had a lathe, milling machine and a scraper back there, in addition to what every one else had.) putting that BSA together. Any part he couldn't buy, he made in that shop. Jerry Branch worked his magic on that head. Several trips to Los Angeles to C.R. Axtell's dyno. He bored out the 38mm Amal Grand Prix carburetor to 1 9/16ths choke (Or venturi) We tried aluminum intake valves. An intake valve to seat technique, that I was forced to agree to never divulge, not even after death! Now a lot of guys own lathes and can make stuff on it. But Andy was an artist in metal on that lathe and milling machine. About this time, a tall gawky teenager started hanging around the shop. He was looking over that Beezer like it could give milk. He was just 18. The youngest you could get a profesional licsence was 18, in the AMA. Typical goofy teen-ager. I thought. Until I saw him ride. A natural, really the only one I had ever seen. His name was Preston Petty. We started going to Ascot Track in Gardena when the season started. He wasn't just faster than the other Amateur racers, he was a lot faster. Well, my typing fingers are getting tired - so 'til later ---Sincerely, ARH

[BlackBike]

Arh... is this that track?
Pictured is preston


Preston is apparently in hard times...there is/was a go fund me for him.
https://www.gofundme.com/jvu3uaw4

[Ariel Red Hunter]

Originally Posted by BlackBike

Arh... is this that track?
Pictured is preston


Preston is apparently in hard times...there is/was a go fund me for him.
https://www.gofundme.com/jvu3uaw4

Yeah, I just visited that site. Sad. He came from a very well to do family. And the girl he married was from a wealthier family. But I don't think her name was Mary. She must be wife number 2. Or 3. Or who knows. You can see from this picture how confident he was as a rider. He approached that jump perfectly in order to be that perfectly set up for his landing. No, that's not Ascot. That's one of the TT Scrambles tracks. My favorite was Prado Park, very smooth, and the surface held up really well, which was good for me, as I used the front brake a lot. Most, if not all dirt racers of those days did not ever touch the front brake. I used to go fartur into the corner doing that. If I won, guys would come up and tell me that I had some engine in order to win like that. Hah!......ARH

[BlackBike]

So amazing you guys rode those "tanks" as hard as you did. Without the modern suspension, and nimble light weight bikes of today. Answer, like doing without air conditioning , didn't know any different and pushed the tcecnoligy it to the limit , naturally



As culcune would say in his reporter like style, member 2lz reports that divorce is not good for the finances

[Ariel Red Hunter]

Originally Posted by BlackBike

So amazing you guys rode those "tanks" as hard as you did. Without the modern suspension, and nimble light weight bikes of today. Answer, like doing without air conditioning , didn't know any different and pushed the tcecnoligy it to the limit , naturally



As culcune would say in his reporter like style, member 2lz reports that divorce is not good for the finances

Tanks? These bikes were 100 to 200 lbs lighter then what people were riding in the forties. They were light-weights! I remember a quote from a Swedish moto-crosser who wanted to try a Harley 74 off road. He ran it over some jumps on a TT track, and said "Yah, goes gutt, but yumping Yesus, it sure hurts ven it come down". My Ajay weighed 370 lbs. Less when stripped for racing. A Harley Sportster weighed around 500 lbs, maybe 480 stripped for racing. I eventually ended up on a Triumph 500cc Tiger Twin. About 320 lbs. I was 6' 1", and weighed 217. I found that Triumph the easiest handling bike I ever rode. You rode it sitting down, except when going over jumps. It felt light to me. It had enough suspension travel for the way we rode in those days. And the way I still do. I don't like mucho suspension travel. Four inches at the back is plenty. More than that upsets the rake and trail too much for me.

[BlackBike]

My comparison was between the "tanks" of the 50's racers vs the "nimble light weight bikes of today. "

[Ariel Red Hunter]

By the way, when you took your scoot down to C.R. Axtell's, you were there, of course for the dyno run. You had to write the numbers down, because there were no print-outs in those (to you guys) pre-historic times. We ran the bikes with full gear (air cleaners, megaphones, etc. on the bike). After the tests were over, over a tall cool one, C. R. would never tell you what someone elses bike pulled on the dyno. If you wanted to know how your bike stacked up against the others, all he would say was "You still got work to do", which meant (or at least this is my understanding) You don't know what you are doing. "You're in the ballpark" meant middle of the pack. "Top shelf" meant you were ready to go head to head with the big boys. Amongst the Beezers of course. And since the Beezers pretty well owned that track, it also meant you were shitting in tall cotton. That also meant when they hung that bag of green lettuce at the finish line, you were in a good position to grab it. That also meant that whatever you had, had to be reliable enough to make it to the finish line under it's own power. One reason the BSA's were so fast on that track was because it had a seperate transmission, so you could change primary drive ratios as well as final drive ratios. The Harleys, Indians and Triumphs all had unit construction, so you could only change the final drive ratios. I carried a notebook with me, as well as an instrument that measured relative humidity, and temperature. I wrote all of that stuff down for every race meet, and cross referenced it to jetting and drive ratios. For each heat race, the semi, and the final (The money) event. And which rear tire for each of the races. Because the races were at night. And the temperature went down, and the humidity went up every hour past sundown. So you changed main jets, gearing, and rear tires for every race, as the night went on. Well, boys, chew this one over for a while....ARH

[Ariel Red Hunter]

All of the things we did on Gold Stars can be done on our little Hawk engines. I go into this in considerable detail because the engine used in the Hawk has a truly rigid bottom end and crank cases. You must have these for a foundation to build your engine on. Otherwise horsepower and reliability will be used up in over coming crank flexing, caused by crank case "panting." Because of the rigid foundation of this engine used in the Hawk (and others), it is possible to build this engine as far as your pocket-book will allow. Or common sense tells you when to stop. You can not take power out-put to the maximum possible, because this engine does not have enough cooling fins to sustain such a power loading. But that is not true of an engine used in a dual sport or a dirt bike, because maximum power is used only for a few seconds at a time. If you build the engine to the max, take it easy on the highway. Long stretches at high power out put, pulling a tall gear, is where you will find the Achilles heel of this engine.

[Ariel Red Hunter]

It seems that after a period of time, a bunch of new people show up on this forum with carb problems. Perhaps you will forgive me when I think to my self, "Jeez, I've talked myself hoarse on tuning carburetors. Why do they keep asking the same questions!" Of course I'm from a previous generation (or 2!), where, you write something down, and remember where to find the info from then on until Brunhilde rides to your side and carries you to Valhalla. To the music of "The Ride of the Valkeries". Whether you are ready to go, or not. So, once again, here goes. Although I prefer Mikuni carburetors because they are easier to tune, even that thingy that comes hung on a Hawk does basically the same things. But, as you may have heard before, the devil is in the details. There are a few things that you should know before even looking at this carburetor. It is not a "pumper" carb. It does not have a "Power Jet". It is relatively simple to set up correctly. But it is also easy to set it up so far out of whack, it will drive you crazy. This is a variable venturi carburetor. The richness of the fuel mixture up to about halfway to 1/4 throttle is controlled by three things. The pilot jet, the cut-away on the lower front lip of the slide, and the idle mixture screw. The mid-range is controlled by the needle, and above 3/4 throttle the main jet controls virtually all of the fuel flow above 3/4 throttle. There is an easy way to set up these carbs, and there is the hard way, where you run from one adjustment to another trying to get good results, usually to no avail. Naturally, I'm going to tell you the easy way. Because I've always been described as lazy. Lazy people always look for the easy way to do things. People who always do things the hard way hate us, because after they have spent hours fouling something up, guys like me come along and fix the problem in a surprisingly short time. So here's the lazy man's way to do this. You start by putting the needle clip in the center notch. Then you set the idle mixture screw out 1 1/2 turns. Yes, I know it doesn't run right. Yet. Next, run it around town for twenty minutes, or so, to get the engine to operating temperature. Then run it wide open for a half mile or more and do a plug chop. A plug chop means you whip out the clutch, and kill the spark at the same instant, keeping the throttle wide open while letting the bike come to a stop, and never allowing the engine to turn even one extra revolution as the engine slows down to a stop. If the plugs firing parts are white to cream color, main jet is too lean. If the firing parts of the plug look sooty or black, main jet too rich. Now you should have a smooth power flow from just above 1/4 throttle all the way up to top speed. Now from idle to 1/4 throttle is pretty well controlled by the pilot jet. Usually, the throttle cut-away from the factory is spot on from idle on up. I like to set an engine like this to idle at 1350-1400 rpm. And then I play with the throttle cut-away to get a hearty "Thump" at the first little twist of the wrist. With the clutch hooked up.

[Sir kayakalot]

Even though you consider it almost common knowledge ARH, just keep repeating yourself because some of us knew it and forgot it, some of us didn't know it, but ALL of us learn so much from you. Thanks

[pistolclass]

plug chop.... voodooo. If I can find the sensor that goes with this It will be on my hawk. still researching.

where should the sensor be mounted? before cat or after?

https://www.aliexpress.com/item/Air-...0-bfeda64d9636

[Ariel Red Hunter]

Originally Posted by pistolclass

plug chop.... voodooo. If I can find the sensor that goes with this It will be on my hawk. still researching.

where should the sensor be mounted? before cat or after?

https://www.aliexpress.com/item/Air-...0-bfeda64d9636

Doing a plug chop is voodoo? It may be Mojo, but it ain't voodoo. It has worked for over 100 years, so it can't be all bad.

[pistolclass]

what I mean by Voodoo is that I have trouble walking a chewing gum. I worked at a gas station in the 80's,like a real gas station that fixed cars and Ed the owner, awesome mechanic too had this chart on the wall with like 16 images of plugs to read them. Except for the extremes, they all looked the same to me. But 14.7 on a digital gauge, even I can read that.