Proper suspension setup is one of the most important aspects of dialing in a bike. It's impossible to make one set of suspension that will accommodate every rider who hops on any particular brand or model of motocross machinery, which is why forks and shocks are meant to be serviced.

We had been riding the 2013 YZ450F with stock suspension for a little while, but it was definitely time for some servicing on the blue beast. When it came time to get the forks and shock freshened up, we called up one of the best names in the business to get the job done: Pro Circuit.

On the current generation of YZ450F, a typical comment is that, while the forks seem to work very well, the rear end is far less predictable. As you begin to get more aggressive on the bike, especially in rougher sections of a track, the rear becomes less stable, forcing the rider be more cautious than they would prefer.

Bryan Wallace glides through a turn with ease thanks to the improved turning characteristics and decreased understeer of the Pro Circuit suspension.

After communicating this to Bones Bacon (suspension guru), and the rest of the Pro Circuit crew, we were hopeful that the big Yamaha thumper would have some reinvigorated agility along with improved bottoming resistance. What we got was a whole lot more than we were expecting.

There are no “ifs”, “ands” or “buts” about it, the 2013 YZ450F comes under-sprung out of the box. Before the suspension really breaks in the forks and shock can handle a decent range of riders, but they soon become a little too pliant for anyone over 150lbs. After Pro Circuit had their way with the Kayaba suspension, the Yamaha felt like a whole new motorcycle.

Not only was bottoming resistance a non-issue, the balance of the suspension between front and rear improved vastly. When braking heavily in rough sections, where the rear end originally wanted to dance around, it now feels much more settled thanks to the re-valving, Bladder Cap Kit, and Pro Circuit Showa Specialty Shock Kit. After setting the sag to 105mm and playing with the rebound clickers, the shock felt brand new.

The Pro Circuit Specialty Kit and Bladder Cap Kit not only look cool but are a vast improvement over stock form. The metal shims at the top and bottom of the spring help decrease binding on the spring during compression.

Paired with the shock, were the re-sprung and re-valved forks that also now have excellent bottoming resistance to match the already buttery-smooth feel of the well-known KYB SSS fork design. An added benefit of the improved suspension balancing is also improved turning.

It is now much easier to hit and maintain your line, on tight inside corners and rutted turns. The front end has less of a tendency to want to climb out of a rut due to under-steer.

Overall, Pro Circuit more than delivered with their suspension tuning. If you are a Yamaha owner, and can afford the moderate price tag of this high-end service, Pro Circuit might have what you’re looking for.

Over jumps and through bumps, the improved KYB suspension has so far handled just about everything we've thrown its way.

Forks

  • Fork Re-valve and Setup Labor…$194.95
  • Fork Re-valve Internal Parts…$108.75
  • Fork Springs…$129.95

Shock

  • Shock Re-valve and Setup Labor…$164.95
  • Shock Re-valve Internal Parts…$119.75
  • Bladder Cap Kit (Includes Bladder Cap, Air Valve, and Valve Cap)…$58.85
  • Pro Circuit Showa Specialty Shock Kit…$124.95
  • MX Spring Tube Assembly…$289.95

For more information, visit www.procircuit.com.

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