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How Mikael Persson has turned a shop bought Yamaha YZ125 into an EWC winning machine…

Concluding the EWC GP of Greece with a double victory on this Yamaha YZ 125, Mikael Persson is now second in Youth Cup, six points behind leader Joser Garcia. Garcia was absent from that last GP due to injury but the young Persson had already proved he can beat him with a win on the final day of the GP of Portugal. And all that on a bike that started its life as a standard motocrosser in Sweden.

We caught up with Mikael Persson during the GP of Greece to get an insight on how a standard two-stroke 125cc motocross bike can be transformed into a perfect weapon for winning long days in the Enduro World Championship.

“Most of the work on my YZ 125 is done in our own workshop in Sweden. There’s nothing unique or excusive on the bike, nothing any mechanic couldn’t find on the market or do by himself. With every new bike we start by taking the engine apart to check that everything is ok, clear or polish some parts and then rebuild it again. Then it’s suspension work that we focus on. But overall, my YZ 125 is a bike loaded with extra parts that anyone can find.”

Both a rider and mechanic himself, Mikael Persson took us through the most major modifications on his mighty 125cc smoker.

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1. Suspension

“The biggest improvement is the KYB A-Kit Factory air fork by Technical Touch. I love the feeling of precision you have with the air fork. The bike can read the terrain better and the front is more agile. I’m running 2.2 bars on the forks, which I have to check after every race day. I really like the feel of the air fork which make a great set with the KYB factory rear shock. It’s probably my YZ’s biggest advantage compared to the KTM I used to race.”

2. Engine

“We run the VHM cylinder head with exchangeable combustion chambers. I prefer using the largest chamber that reduces compression and gives a wider power band. We use a standard flywheel and standard internal gearing. But we change the sprockets to a set of 12 – 49. The bike is a bit slower in the liaison sections but I only use 2nd and 3rd gears in special tests. Carburetor is standard Mikuni 39mm with different settings inside, depending on weather conditions and altitude. Overall it’s a standard and well-prepared engine with extra parts anyone can buy.”

3. Chassis & Cockpit

“As a relatively small guy I like the YZs dimensions. We use the standard subframe but have lowered the rear part of the bike using an extra spacer on the linkage. I think this part is 3mm shorter which brings the rear end 20mm closer to the ground. I’m using low Renthal 999 bars which I normally bring closer to my body. It helps get into the attack position easier and lets my arms stay lower when I sit up. I really love levers being closer to my hands. I’m using ARC brake clutch levers.”

4. Extras

“My aluminum tank is made by X-Fun and can carry 1.5 liters more fuel than the standard without affecting the riding position at all. I can make a 65km enduro lap before refueling. We also use XTrig clamps and Polisport plastics. I have an oversize front disk by Galfer that’s combined with high pressure brake lines. The mud-specific rear disk is also made by Galfer and it’s not locking so easy, you can brake hard without it locking.”

5. Electricals

“Probably the only addition we’ve made is a battery by Ballistic which runs independently and is charged after every two GPs. It’s a really small battery that we fit under the seat and inside the air box. I’ve got a main power switch on the bike so I can choose when to have lights or not, but normally I don’t use the battery for more than 10min per race. We use LED lights front and back. I recharged the battery after the GPs of Spain and Portugal and it wasn’t close to empty yet.”

6. Overview

- Metzeler tires (soft front – big rear)

- Metzeler mousses

- HGS exhaust (enduro-specific, bigger housing and longer dimensions)

- CrossPro plastic mud guard

- Boyesen clutch parts and engine caps

- Raptor titanium pegs

- TMD chain guard

- Hammerhead gear lever

- Supersproxx sprockets

- RK chain

- 18’’ inch rear wheel by SMPro