MXA TEAM TESTED: PRO CIRCUIT 2022 YZ125 PIPE & SILENCER

WHAT IS IT? The Pro Circuit Works YZ125 pipe has been the workhorse of Pro Circuit’s two-stroke pipe line for many years. Why? Because the pipe fit the 2005 to 2021 YZ125s with very few modifications over the last 16 years. But, since the standard-issue Pro Circuit YZ125 pipe does not fit on the 2022 Yamaha YZ125, Pro Circuit had to design a new YZ125 pipe.

WHAT’S IT COST? $292.46 (Works pipe), $362.95 (carbon fiber silencer), $155.95 (aluminum/stainless silencer).

CONTACT? www.procircuit.com or (951) 738-8050.

WHAT STANDS OUT? Here’s a list of things that stand out with the Pro Circuit Works pipe and 304 silencer for the 2022 Yamaha YZ125. 

(1) Comparison. First of all, before you even consider spending hop-up money on the 2022 Yamaha YZ125, you have to fix the stock jetting down low. It is a blubbery, boggy mess. Your jetting is dependent on your local elevation, temperature, humidity and track-load factors, but we went a little richer on the main jet (from 160 to 162), leaner on the pilot (from 75 to 72), and stuck with the stock needle but moved the clip up and went 3-1/2 turns out on the air screw. 

Given the number of changes that Yamaha made to the YZ125 for 2022, we expected it to blast the 2021 YZ125 to smithereens. That didn’t happen. The 2021 YZ125 was stronger down low (from 5000 to 7500 rpm) by a full horse. This was very noticeable on the exit of corners. After 7500 rpm, the 2022 YZ125 was stronger by 0.5 horses to 0.75 horses until 10,500 rpm, where the 2022 YZ125 gapped the 2021 YZ125 by a full horse up to peak at 11,500 rpm. That one horse was noticeable in a positive way—in that it was a strong enough addition to the power profile to change the 2022 YZ125 into more of a high-rpm engine than the 2021 YZ125. Both the 2021 and 2022 YZ125s signed off at the exact same 11,600 rpm, where they both dropped like a rock. 

No lie, we had been expecting significantly more than 34.4 peak horsepower out of the 2022 YZ125, especially since the KTM and Husqvarna peak at 37.5 horses (a 3-horsepower advantage).

(2) Performance. Pro Circuit’s 2022 Yamaha YZ125 exhaust doesn’t change the way the YZ125 runs down low, but from 9500 rpm all the way to peak, the Pro Circuit pipe and 304 silencer build power quickly with the benefit of a broader top-end and added over-rev. The Pro Circuit 2022 Yamaha YZ125 pipe makes 35.8 horses at its 11,600 rpm peak, which is 1-1/2 horses more than the stock YZ125 at peak. The Pro Circuit pipe doesn’t have any major differences from off idle to 9500 rpm, but from there on up it packs a punch into the high-rpm sector. However, high rpm is where the 125SX, TC125 and MC 125 dominate.

(3) Silencer. The stock Yamaha silencer has been shortened 2 inches for 2022, but it is still 17 inches long. That may be shorter than 2021’s bazooka, but Pro Circuit offers three mufflers that are shorter than the YZ125 stocker. We tested with the 10-inch-long 304, but for bucks-up riders, Pro Circuit makes a 9-inch-long carbon/Kevlar/Ti Shorty silencer for $362.95, which is what Ryan Villopoto runs.

WHAT’S THE SQUAWK? Getting a Pro Circuit pipe could require a wait, as the current supply shortages of metal and stampings and lack of qualified labor have slowed production at Pro Circuit’s Corona, California, plant.

MXA RATING: We waited 16 years for a “KTM beater” YZ125. When it finally hit the showroom floors, it was 3 horsepower short. The Pro Circuit Works pipe narrows that gap. It boosts mid-to-top power, which makes the YZ125 more raceable.

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