American Smoker: Harley-Davidson SX175 Flat Tracker

Harley-Davidson SX175 Tracker

From Kaleb Zink: Harley-Davidson Tracker for Flat Out Friday… 

In the early 1960s, Harley-Davidson saw the rising popularity of smaller displacement bikes like Honda’s OHC twins and cut a deal to purchase half of Italian company Aermacchi. The “Italian connection” would last until 1978, resulting in a series of rebadged H-D machines unlike anything else to come out of the Motor Company.

Most folks don’t realize what a winning connection it would be. A Harley-Davidson Baja 100 placed first in class at the 1971 Baja 1000, and then there were the Grand Prix victories.

“Harley should be proud of the Italian connection, because it provided the company with four international GP racing victories when Italian road-racer Walter Villa won the 250 class in 1974, ’75 and ’76, doubling up in 1976 by winning the 350 class as well — riding a parallel-twin two-stroke built by Aermacchi with Harley-Davidson writ large on the fairing.” -Clement Salvadori, Rider

Walter Villa

In the mid-70s, the two-stroke SX series enduros appeared to compete with machines like Yamaha’s hugely successful DT series.

“Aermacchi Harley-Davidson’s first real counter-offering to the DT-1 came five years later with the 1973 SX125, followed quickly by the 1974 SX175 and finally the SX250. The SX175 and SX250 were essentially identical apart from the 250’s larger cylinder bore.” –Motorcycle Classics

Harley was serious about getting a chunk of the enduro market, and the SX175 and 250 were packed with features such as adjustable Marzocchi suspension, quick-change ISDT-type rear hubs, built-in spark arrestors, and a breakerless CD ignition separate from the battery system, so riders could strip down the bikes for off-road riding and racing. While the SX series might not have performed quite as well as its Japanese rivals, these bikes had something no one else could claim: the name Harley-Davidson on the tank.

The SX175 flat tracker you see here comes from 34-year-old former woods racer and current custom paint artist Kaleb Zink of Florence, Missouri…but the bike has quite a long history behind it.

“I had purchased this bike five years ago from my original motorcycle mentor, Bob Jeffress, who had originally purchased it new for his wife, Linda, to commute back and forth to college. Bob’s parents had owned a small Harley shop in the small town of Syracuse, Mo. She made the commute nearly 50 miles one way for two years before upgrading to a SS-250.”

Original owner Bob Jeffress

After that, the Jeffress brothers stripped down the SX and took turns racing it. Growing up, aspiring woods racer Kaleb developed an early love for the Harley orange dirt bike at the Jeffress house. After taking the bike off his mentor’s hands, Kaleb reconditioned the bike and showed it in “woods trim” at Fuel Cleveland in 2022.

Harley-Davidson SX175 woods racer
Woods Trim

Then he got the idea to race the bike at Flat Out Friday, the indoor flat track event hosted every February during the Mama Tried Show…raced on cola syrup instead of dirt!

“This will be the second time competing at this event, and it only seemed fitting to race a Harley in Milwaukee!”

Harley-Davidson SX175 Tracker

The wheels were swapped for a set of 19-inch D.I.D. DirtStar wheels wrapped in flat track rubber, and the bike is now sporting a GSX-R front end with the steering stem, bar mounts, front axle, and spacers machined by Kaleb’s father, Paul, who owns Zink Machine Tool and Fabrication in Warsaw, Missouri. A Harley XR750-style tail section was modified to fit, and the rear outfitted with a hydraulic disc brake — no front brake, of course, as this is a flat track bike.

Harley-Davidson SX175 Tracker

Of course, Kaleb himself handled the paintwork — the tank is the only fully original paint on the bike — and enlisted the help of local Missouri craftsmen and workshops for other needs: A&B Auto Trim for the seat, Pat Shull for the exhaust repair, and Jake Owens for the heat treating and polishing.

Harley-Davidson SX175 Tracker

This is one gorgeous flat tracker that oozes style and history, and a gorgeous tribute to a motorcycling mentor. We can’t wait to see Kaleb sling it sideways on the syrup next month at Flat Out Friday — we’ll be rooting for you, Kaleb!

SX175 Tracker: Builder Interview

Harley-Davidson SX175 Tracker

• Please tell us a bit about yourself, your history with motorcycles, and your workshop.

My name is Kaleb Zink from Florence, Mo. I am creeping up on 35 yrs old and have been riding motorcycles since I was 8. Most of my early riding consisted of field riding, which turned into woods racing. I started hare-scrambling in 2004 and raced steadily until 2013. I fueled my love for motorcycles in 2011 by taking a position at our local Harley-Davidson dealership (Yeager’s Harley-Davidson) working at the parts counter. That’s where the real addiction for motorcycles began…

Harley-Davidson SX175 Tracker

In the evenings, I am able to couple my passion for motorcycles with my love for art and painting and combine the two. I have been practicing custom paint work for 15 years and it seems that the motorcycle remains my favorite canvas.

• Why was this bike built?

I had purchased this bike 5 years ago from my original motorcycle mentor, Bob Jeffress, who had originally purchased it new for his wife, Linda, to commute back and forth to college. Bob’s parents had owned a small Harley shop in the small town of Syracuse, Mo. She made the commute nearly 50 miles one way for two years before upgrading to a SS-250.

The SX-175 then was stripped of its turn signals and street tires and became destined for the woods. The Jeffress brothers took their turns racing the bike for the next few years before upgrading to the new MX-250. The original tins for the bike were stowed away on a shelf as the forks were hard on gas tanks!

Harley-Davidson SX175 Tracker
Bob’s brother, Rex Jeffress, who also took a turn racing the motorcycle in the late 70s-early 80s.

My family grew up with horses, not motorcycles, so every time there was a need for a fresh spark plug or a quart of two-stroke oil for my first dirt bike, Bob’s house was the place to go. Every time the door would open, here sat this orange Harley-Davidson motorcycle with knobby tires…I was hooked.

Harley-Davidson SX175 Tracker

It has gone through its last transformation to be able to race in the vintage class at Mama Tried’s Flat Out Friday event held in Milwaukee in February.

Harley-Davidson SX175 Tracker

When I decided it was going with me up there this year, there was only one way to reintroduce the bike to the racing community: as a fresh new motorcycle! The gas tank paint is the only original paint left on the motorcycle that has not had any re-conditioning. Powdercoat was done by Sure Coat in Sedalia, Mo. Machine work was completed by my dad, Paul Zink, owner of Zink Machine Tool and Fabrication in Warsaw, Mo. Bike was shown in its “woods trim” at the Fuel Cleveland motorcycle show in 2022.

• What was the design concept and what influenced the build?

I wanted to create something with the race style that I love that was also pretty enough to stare at.

• What custom work was done to the bike?
  • GSXR front end: machined steering stem, handlebar mounts, front axles and spacers from Zink Machine Tool.
  • XR style tail section shortened and trimmed to fit.
  • Rear hydraulic disc brakes.
  • Seat by A&B Auto Trim Sedalia, Mo.
  • Exhaust: Power Pipes Jr, repaired by Pat Shull and polished/heat treated by Jake Owens — both of Sedalia, Mo.
  • Paint work: Zink’s Custom Paint, Florence, Mo.
• Can you tell us what it’s like to ride?

Only have had a few test sessions with the new tracker setup, but the bike was always fun to ride, making fun sounds all the way through the RPM range!

Harley-Davidson SX175 Tracker

• Was there anything done during this build that you are particularly proud of?

Completing the bike in time to race Flat out Friday! Took many hours of sleepless nights to complete while maintaining a normal daytime life.

Harley-Davidson SX175 Tracker

Follow the Builder

Instagram: @kzink643 


  1. awesome!
    I want it

  2. What a fun build, you just don’t see many Harley 175 flat trackers. I like the work that went into it, especially Dad’s machine work on brackets and the brass pieces. paint looks great too. Thanks for sharing this build and good luck at the next race.

  3. No porting? seems like such a waste for such a well thought out bike. Certainly not stock with the chamber, is it? Hope there was more done than just that!! She’s a beauty……..

  4. Cute little tracker.

  5. Charlesross

    This is an Italian smoker only thing Harley is writing on tank these bikes were junk they were built to compete with jap. Bikes and they were a miserable failure that’s why they are not around anymore I am 64years old and remember them well the sprints were junk also.

  6. Col.Mustard

    Reminds me of the Kesco Engineering DT175, and DT250. Kesco was owned by Jack Krizman, Jack was an engineer for Harley and designed/developed a lot of the 2 stroke models for production as well as working in the Race Dept. Kesco sold race/Hop up parts/kits for the Harley Aermacchi and later Harley Cagiva bikes.

  7. Michael Hegyan

    Very friend. I started riding, back in 73’, Yamaha mini ride a couple Harley’s, Street Glide, and 114 Hertaige Classic..

  8. Perry Bradshaw

    In 1992 one of my good friends gave me a SX 175 that had been his since new! It sat in my Garage for four years had Tinkered with her found out how hard parts were to find it just sat there! Later that year I bought an Bultaco Alpina at a swap meet in Fredericksburg Virginia so the SX Went back to its original owner and I am sure he still has it he keeps everything! Your SX turned out nicely I Love FlatTrack Bike Your Harley Davidson SC looks Awesome enjoy it!

Leave a Comment

Your email address will not be published. Required fields are marked *