50 Years at Bonneville - Scott Guthrie Remembers

[Old-N-Slow]

50 Years at Bonneville
Scott Guthrie Remembers
Chapter #37b

March of 1983


I wandered around the Daytona 200 pits, learning what I could.  I had been attending Daytona Speed Week since the early 1960?s, and spent a LOT of time in the pits ? dreaming and remembering. The Daytona 200 mile road race ? once the biggest and most important motorcycle race in the world, entertained tens of thousands of spectators, and perhaps tracked over one thousand riders in all classes for the week.  Through the years, I found that I could trace success and (more usually) failure by identifying an interesting entry, and following his doings throughout the week, and noting what had had done.

It was always interesting to peek ? when allowed ? into the factory areas, and see what unlimited funds could produce ? and it wasn?t always success.

We garaged NEXT DOOR to the Yamaha factory race team!  Kel Caruthers, Kenny Roberts, Eddie Lawson, swarms of Asian mechanics.  The team that year was riding Yamaha V-4 grand prix bikes of mysterious specification.  Actual displacement was originally 500cc, but the AMA allowed up to 750cc, so discussion ranged between these numbers.

The team wasn?t talking!

After a few days, I wandered over to the AMA track office and asked to see the entry form for Kenny Roberts bike.  The form disclosed the bore, stroke and displacement truth.  I kept quiet and enjoyed hearing the speculation.  The Yamaha 0W69 displaced 680cc

One evening near the end of the working day, the Yamaha garage was in a flurry of finishing up Kenny?s bike for practice the next morning.  A younger oriental mechanic pushed the hurriedly-completed #2 bike out to the driveway for a push start, without the fairing, ? probably to check for leaks and drips.

 
Photo - Kel Caruthers ? Kenny Roberts?s tuner and himself a 250cc MotoGP Champ, paddles Kenny Roberts 0W69 around the pits.  When asked about the bore, stroke and displacement, Kel just smiled. My rider John Long was not as fast but he had respect; neither Lawson or Roberts passed Long in the turns; only on the straightaway.

I noticed the other mechanics ? and Kel Caruthers ? smiling and winking to each other and drifting out to watch the test.  The bike fired immediately ? and revealed that the junior mechanic had forgotten one of the exhaust pipes, and the future race winning bike was making awful blatting noises!

After much laughter, the pipe was properly installed, and the test was completed. 

On the Sunday, Kenny would win the 200 mile race at record speed on this same bike.

1983 saw the introduction of what some thought was the first real superbike ? the Honda V45.  With a V-4 architecture, alloy frame and modern alloy chassis, the bike was complicated, heavy and muscular.  It was also going to put in a victory by over 60 seconds in the Superbike race on Saturday.
 
Photo - Daytona winner John Ashmead lines up at the start.  Does his bike look like the pictures in the catalog?  His Day-Glo helmet stripes were emblematic. Did 16 inch front tires actually work better for Ashmead than 18 inch hoops on World Champion Fred Merkle?s factory bike?  Race results do not always answer the ?better? questions.
 
Photo-The Interceptor architecture was 4-stroke up-to-the-second design!  Double overhead cams, block with four cylinders cast as a unit with the top crankcase half.  As a privateer used to working alone, I trembled when I watched Roberto Pietri?s factory mechanics struggling to get that big lump out of the bike and onto the floor, then onto the bench.


The happy result on that sunny March Sunday afternoon was Long?s strong 8th place against an international field of more than 100 Factory riders, pre-entered riders and many factory supported riders. 

John Long had done well for us.  An eighth place was relatively high for him, and was far higher than any effort I had been associated with - and far better than I had expected.  John did the mechanical work himself ? being VERY frugal with both his time and my borrowed money.  He was doing things I could not have ? and probably never could have done ? and he did it in a very gracious way.

In appreciation for my 1983 sponsorship, John prepared an older 350cc Bultaco TSS factory (water cooled !) road racer for me to campaign in the Vintage classes that same Daytona race week.  I had never before road-raced a 2-stroke bike, and had never ridden Daytona?s steep banking, which was pretty intimidating. 

Not having road-raced in 10 years was no help either.

It did not go well.

In 2020, John Long and I have had a friendship for almost 40 years.  In that time, especially in the beginning, we have occasionally had a relationship that threw sparks, but for many years has been pretty cordial.  I think I was a pretty abrasive nerd, and John showed remarkable tolerance for somebody like me with no talent and reduced social skills with people at the sharp end of world-level road racing.  He often shared knowledge with me as if I could understand.


 
Photo - Bultaco TSS Aqua water-cooled factory bike.  Note big front brake compared to customer version.
 
Photo ? Air cooled version was a factory racer intended for customers, while the factory riders were issued the water-cooled version.

 

Photo - John Long@ Bonneville in 1990.  Yamaha TZ250 running special Guthrie bodywork.  Rain threatens!  John is a world class rider and has also ridden widely in the USA, England, Europe and Asia, and in 1990, was also riding this same 1983 Daytona race with me.  In 1983,  Long was well qualified to critique my road-race riding from the field.  I still remember his dead pan delivery after our mutual running in the vintage race, which he won the race, I was 14th:  ?I thought there was a whole team in the same leathers and the same kind of bike, and then I realized it was only you, and I had passed you maybe three times!? Jon Nalon Photo

Paybacks are tough.

PHOTOS:  In the original articles, lovingly published by Wendy at the BONNEVILLE RACING NEWS, there were PICTURES !...It is a little too cumbersome for me with my 76 year old pre digital brain to post those here since it involves photobucket and things like that.  IF you go to my facebook account, the pictures are attached to THAT version of these articles..........https://www.facebook.com/scott.guthrie.3154.........

[Old-N-Slow]

50 Years at Bonneville
Scott Guthrie Remembers
Chapter #38

1983 ?:  MY 2nd BONNEVILLE RAINOUT!

Expectably enough for me, the 1983 Bonneville racing was rained out, just like my canceled first appearance in 1972  - also for rain.  My earth-shattering re-debut would have to wait at least another year.

Rain ? outs, before the year 2000, seemed to happen two years in a row, about every 11 years. Like 1960-61, 1971-72 and 1982-83, sort of like the cycle of sun spots ? which is every 11 years also.  The rain-outs have been irregular since then ? maybe because of global warming?

My major Sponsor at Daytona ? other than my unsuspecting credit union ? was Honda dealer Woody Leone of Beaumont Texas.  He appears as DynOmni on my bikes.

Woody was a Bonneville racer too, and eventually either rode on, or helped tune for, 68 Bonneville records ? often teaming up with nearby Jack Wilson of Triumph of Dallas.  Woody was a former member of the powerful AMA Competition Committee, and had invented a type of water-brake dyno especially for motorcycles.  Woody was later inducted into the American Motorcyclist Association (AMA) Hall of fame ? one of the highest honors in American Motorcycling.

Woody invited me to his R&D department in Beaumont to improve my TZ750 and I jumped at the chance.  Woody, trained on the ancient British singles and twins of the 30?s to the 50?s, actually had A LOT of Yamaha TZ750 dyno experience!

The AMA ? leader of all things motorcycle in the USA - and most of the professional racing staff had discovered that by the late 1970?s, the TZ750 was WAY faster than all the competition, and maybe faster than most of the riders were capable of riding safely.   Following the lead of NASCAR, the AMA decided that carburetor restrictors were called for, and my friend Woody ? because of his dyno inventions, and his position on the AMA competition committee ? was chosen to do the TZ750 research as to the restrictors.

Woody was a seemingly laid-back kind of guy, who died still vigorous at the age of 78 of cancer, but he was intensely intelligent.  Without graduating from high school, Woody had done the research and development to allow him to be issued US patents in such disparate fields as oil drilling equipment, motorcycle testing devices and airplane propeller straightening machines.  I never found an area of mechanical study that he was ignorant of.

Other than my father, an architect, I had never heard anyone else discuss parabolic hyperboloids.

Immediately after Daytona, I set off for Beaumont.  One of the things I have used ever since the Texas dyno sessions is a visceral understanding of how much carburetor settings affected power output.  I could look at the plugs and tell how much more power I could find by changing the jets.  As I became more experienced with racing, I could figure out how much more power ? and more speed - I could get with certain tuning changes.

If my changes would result in increased risk of engine failure, I could make that decision: Power or Reliability.

Woody pulled some books from the shelf in the R&D offices.  He handed me a three-inch thick binder and said: ?In my experience, this is the stuff that doesn?t work in racing.  This little 1/8 inch thick pamphlet are tricks that actually work.?

 
Photo ? Woody Leone as I remember him ? with a big smile and a full-on race bike!  Woody was a Honda motorcycle dealer who got in EARLY, and had a two-digit dealer ID number.  He had tuned for famous names and national numbers. I was proud he would take his time with me. Not a shy man, he was somehow unable to resonate with the post 1985 crowd, but I has more than happy to have his attention.  Long after he passed away, I was proud to have his decals on my bikes.

Woody also demonstrated the success available with the same fuel flow from DIFFERENT carburetors! We had been testing with the 34mm Mikuni VM34mm carbs the TZ750 came with.  We saw maybe 110hp at the rear wheel with marginal-but-ok-on-the-dyno tuning.  We fit a set of 34mm Lectron carbs with the same jetting, and the power went up by 10hp!  How much porting and pipe making (time and money spent) would I have to have done for the same result?

 
Photo ? What have we here?  SMOTHERED in new parts, this looks like an ordinary Yamaha TZ750 engine, but there is NO serial number, and the castings don?t look quite like the factory die-cast units.  The cylinders have strange cast markings too.  The intakes are a little odd, and Yamaha certainly never issued those LECRON carburetors!  The TZ750 is so desirable almost 50 years after production began that it is possible to built a ?replica? engine from almost exclusively new parts.  It is NOT cheap, ONE new engine today would cost more than FIVE COMPLETE NEW BIKES in 1974 !

One outcome is that I have been using much the same tuning answers for almost 40 years at Bonneville.  In August of 2020 at Speed Week, we ran a bike that ? supposedly down 20 horsepower on our competitor?s bike ? took his record by almost five mph.  In the next meet, he then took the record back! 

We thought we found more speed, and that new-found potential induced us to go back in September and try again, with ONLY drive-line changes.  Result was an unexpected 20 mph increase in speed. 

ALL at almost no cost in money or time.

While waiting for the bike to cool between dyno runs, Woody talked about water injection and ?trombone exhaust.?

One of Woody?s racing friends was a champion hydroplane racer in the smaller classes ? about 250cc 2-stroke, if I remember correctly ? and he had his secrets too!

The first was something he called ?The Trombone exhaust.?

At the time, this was the only trombone exhaust I was familiar with:  https://www.youtube.com/watch?v=kwaXjtRybhI

The modern 2-stroke exhaust ?expansion? chamber offers MUCH more power than the typical ?straight? exhaust, and also much more than the ?megaphone? style.

 
Photo: Early 2-stroke outboard racing engine.  Megaphone exhaust was annoying, loud and abrasive, and not that good for power.  Kind of 1950?s thinking. ?Bang and blat was loud, but NT fast ? a common confusion?


Although a decent tuned pipe can be made of just a few components, it is the relationships between the lengths, angles and sizes that makes the critical differences in power.

 
Photo:  simple modern 2-stroke exhaust, but without silencer fitted. Note straight, parallel-wall center section


 
 
Photo:  expansion chambers simply described.


Of all the components, the straight center section with the parallel sides was what concerns us for the ?trombone effect.?

PHOTOS:  In the original articles, lovingly published by Wendy at the BONNEVILLE RACING NEWS, there were PICTURES !...It is a little too cumbersome for me with my 76 year old pre digital brain to post those here since it involves photobucket and things like that.  IF you go to my facebook account, the pictures are attached to THAT version of these articles..........https://www.facebook.com/scott.guthrie.3154.........