Short Track Weapon: Yamaha YZ250 Flat Tracker

Swedish champion Ake Jansson builds a two-stroke tracker!

In 2001, Motocross Action magazine claimed the ’01 Yamaha YZ250 was the world’s best 250 production motocross machine. The engine was the highlight, a liquid-cooled mill that offered 44.5 peak horsepower over a broad powerband:

“Not only is it fast, but it’s smooth. Not only is it smooth, but it’s broad. Not only is it broad, but it’s crisp. Not only is it crisp, but it’s flexible. Not only is it all those things, but it’s more.” —MXA

Those motocross test riders, ripping up the track at the start of a new century, probably didn’t expect to see their YZ weapons on a flat track oval 20 years later, but that was exactly the vision had by Sweden’s Ake Jansson (@FlattrackSweden). By day, Ake is a 56-year-old technical service manager for a large mining equipment manufacturer. Catch him outside the office, however, and chances are he’s in the garage or at the track.

Ake’s racing record is quite staggering. Not only did he compete at a high level in enduro for many years, participating in the International Six Days Enduro (ISDE) and the European and Swedish Championships, but he’s a five-time Swedish national champion in hillclimb competition and the 2018 winner of the Swedish Flat Track Cup — a sport he’s been working hard to promote in his home country:

“For the last eight years, I’ve tried to make flat track a sport here in Sweden — it’s been a slow start, but now we see many new people and builds coming into the sport.”

In fact, one of the primary goals of this project was to show other enthusiasts that they could build a potent flat-track weapon out of an old two-stroke motocross machine:

“The idea was to show people that it’s possible to use an old two-stroker for flat track. And I had a vision in my head how it should look for years now — I had to build it.”

He bought an old 2001 YZ250 in pieces — a true basket case — and got to work. This smoker now has R6 forks, modified JSV exhaust, a 13-oz flywheel, 19-inch wheels, speedway air filter with 3D-printed holder, a custom fuel tank built with the help of Mikael Sjövall at Kings Plain Garage, and more.

Just last weekend, Ake had his first chance to test the newly built machine on the track, and he was very happy with the results:

“Tested the YZ this past Sunday and everything worked beyond expectations — good torque, good traction. The heavy flywheel (13 ounces) was useful and the exhaust pipe from JSV was well suited for this type of riding. Some minor adjustments are needed, then I’ll have a sharp flat track weapon for short track.”

Below, we get the full details on this two-stroke track weapon!

Yamaha YZ250 Tracker: Builder Interview

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

Ake Jansson, living in Örebro, Sweden. I work for a large company producing mining equipment and mining machines as a technical service manager. I started riding motorbikes when I was just 3 years old, and I’m still riding at the age of 56.

Started off with enduro, managed to compete on high level for many years, participating in the International Six Days Enduro, European Championship, Swedish Championship, November Kåsan, etc. Then I started to race hill climb, the Swedish version on gravel roads, and ended up as number one in the Swedish Championship five times.

For the last eight years, I’ve tried to make flat track a sport here in Sweden — it’s been a slow start, but now we see many new people and builds coming into the sport.

In 2018, I converted a Honda Transalp into a flat tracker — on that bike I finished as number one in the first Swedish Flat Track Cup. That bike is still running but now in Norway.

• What’s the make, model, and year of the bike?

The bike is a Yamaha YZ250 2001 motocrosser. I bought it in parts, everything was taken apart, lying in boxes.

• Why was this bike built?

I have been thinking of building a two-stroke flat track bike for some time now, looking for donors. The idea was to show people that it’s possible to use an old two-stroker for flat track. And I had a vision in my head how it should look for years now — I had to build it.

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

My idea was simply to build a bike that would work well for flat track racing, a two-stroke bike.

• What custom work was done to the bike?

Gas tank custom-made from sheet metal. My friend Mikael Sjövall at Kings Plain Garage helped me with this.
Rear frame / subframe custom-made from square tube steel.
R6 front forks.
3-D printed air filter holder.
Speedway air filter.
Small radiator guards made from aluminum.
JSV Exhaust with silencer, slightly modified.
Special machined spacers to fit the R6 fork in the standard clamps.
19” 2.50 rear rim / 19” 2.15 front rim.
Left side foot rest modified to handle the steel shoes.
Modified brake pedal, lowered.

• Does the bike have a nickname?

It’s this year’s winter project, so why not the “Covid Project.”

• Can you tell us what it’s like to ride this bike?

Tested the YZ this past Sunday and everything worked beyond expectations — good torque, good traction. The heavy flywheel (13 ounces) was useful and the exhaust pipe from JSV was well suited for this type of riding.

Some minor adjustments are needed, then I’ll have a sharp flat track weapon for short track.

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

The support of my friends, who helped me with the build.

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