Mike,
Please -- just Pete is fine. The "Mr." is completely unnecessary!
I'll get two minor things out of the way: I'm 60 years old, and live in central California (don't hold it against me guys!).
The way I got into karting was a bit back-handed. I had started working in my dad's machine shop when I was about 12 or so, but after getting out of high school, I also worked at a motorcycle shop assembling new crated motorcycles. (I was motorcycle racing flat track at the time). There was another mechanic that worked at the shop who was a bit older, and he would tell stories about his go-kart racing in the late 60's. It sounded like a lot of fun, so I found a kart shop close by (Meyer's Speed Shop in Bellflower, CA) and went and checked out karts. I wasn't that far from Azusa Raceway either (which I believe was the first "dedicated" paved sprint track for karting in the U.S.). I went up and watched a race and was immediately hooked. This was late 1974.
My first kart was a Bug Stinger sidewinder with a Mac 91. I ran some races, but then I happened to see a brand new road-race kart (what we called an enduro kart back then) sitting at Meyer's Speed Shop. Now I was *really* hooked! I had to do that! I picked up a used Lancer enduro kart, and started running Reed Light and Reed Heavy (McCulloch engine) at every race I could make in California. By late 1977, I had moved to "Open" class, and to me, this was nirvana. Along the way, I built multiple enduro chassis and scratch-built some water-cooled open engines. I also designed and built exhaust pipes, carbs, clutches, etc. Anything I thought I could make better, lighter or different... I tried it.
As far as "biography' as a racer, I'd say most of my racing was enduro/road racing from 1975-1985. I still had a sprint kart (direct drive) that I played with and tested engines on into the mid-90's.
Back in 1977 or 1978, I also started building kart engines for customers. I was still working as a machinist for my dad's business, but started my own business on the side which quickly became my profession. Over many years, my "focus" slowly evolved into less engine building, and more machine work for other engine builders. By the mid-90's, I was building very few complete engines, but had over 100 kart shops and engine builders all over the country as customers for machine work (a few overseas as well). I would blueprint lower ends, rebuild cranks, size and straighten con-rods, do failure analysis on parts... pretty much anything. Many of the top engine builders in the country were sending me work. That line of work evolved and narrowed even more, until 95% of my work was blueprinting lower ends (specifically sleeving and line-boring cases). This was all 2-cycle engines.
Around 2004 or so, I could see that karting was changing -- there was a strong move toward "spec" engines, and in general, more and more classes were not allowing significant machine work on engine parts. I had a well-equipped shop, so started taking in more non-karting work and branching into other fields. By 2009-2010, I also started volunteering/mentoring in the Engineering Dept at a technical university. In 2012, I submitted a resume to Apple Inc., and was interviewed and subsequently hired to set up, staff and manage a development facility. I closed up my shop (kept a good portion of my equipment though), and worked for Apple for about 3 1/2 years (until I couldn't tolerate the bureaucracy any more, haha!).
Now I am semi-retired (and busier than ever). I have a fairly nice machine shop in my garage, and I occasionally accept interesting jobs, but mostly just make things for myself.
As a side note, I should give credit where due for a good portion of my background: my parents were European and immigrated to the U.S. in the early 50's. My dad worked for a company in Switzerland that built gear grinding equipment. From way before I can remember, I had a fascination with anything mechanical or technical... and my parents promoted that. By 8 or 9 years old, my dad would often take me along to his work on Saturdays (he was the chief of technology for a huge aerospace company), where I was exposed to the most high-tech manufacturing that existed then (mid-60's). This company was making everything from the fuel pumps for the Saturn V rocket, to huge drive gears for Navy ships, and all the way down to parts so small you had to look at them under a microscope. Along the way, my dad would always explain everything and answer every question. That extensive technical background starting at such a young age (especially in understand very precision machining) was a big influence on my life.