Pro Circuit Pipe and Silencer for Yamaha YZ250

What it is

• A performance pipe for Yamaha's YZ250.

Pro Circuit had produced this stamped and welded pipe and silencer combination for the Yamaha YZ250 from 2003 to 2015. It claims an increase in horsepower and torque throughout the RPM range. Made from stamped AKDQ high-quality carbon steel with hand welded and pounded seams, it has reinforced mounting brackets and braced stinger. The Works Pipe (tested here) has a bare metal finish and takes extra care to keep from rusting but is also available in a platinum version that has an electroless nickel plating. The R-304 silencer is a shorty design and made for closed course racing. Using Hex head screws the inlet cap that can be removed easily for quick re-packing of the silencer. Additionally the intake tube is 304 stainless tubing with a double-walled mounting bracket on the 6061 T6 brushed aluminum silencer body including a stainless steel end-cap. The muffler is tig and mig welded for strength and durability. E-Glass internal packing is used for maximum life and the pipe and silencers are made in the USA.

How it works

• Bolts on in under 10-minutes, pipe and muffler.
• A noticeable boost in power without needing to change anything else.
• Makes short shifting easier and more rewarding.

Fitting the Pro Circuit pipe and muffler is a simple 10-minute job. Everything lines right up, you just have to exchange the O-rings on the pipe and rubber gourmets on the muffler. The bare metal finish looks factory on the bike and if you treat it with a little WD40-type oil it will color nice and blue on your first ride if it isn’t too muddy or wet.

With a shorty muffler, the noise, especially when you crack the throttle is a little more noticeable but it still under the 96 db stationary sound test, believe it or not. We ran our bike on pump gas and started with stock jetting as a baseline, even though Pro Circuit recommends mixing in a little VP C-12 race gas to get the most out of the pipe.

The YZ250 is known for being very crisp, smooth yet aggressive on the bottom and with a power spread that builds very linearly, and for some, signs off just a little early or does not have the overrev some riders prefer. The PC pipe changes the character of the power just enough to be different and not lose the strong points of the YZ’s style. Without changing anything the pipe gives the Yamaha more hit or snap off the bottom as it alters the jetting ever so slightly. Most faster riders preferred this snap and hit especially on tracks with better traction. But we could also lean out the fuel screw and get the smoothness right back and at the same time the bike picks up at a lower RPM. Then through the whole powerband both the torque and horsepower feel boosted. If there was a proper way to describe the difference it is like you added a tooth to the rear sprocket as the YZ pulls just that little bit better everywhere. And as a bonus the sign-off is less abrupt and feels like it happens at a later RPM, though you don’t seem to run into it as much since it is easier to shift earlier and still have aggressive pull.

With this boost in power the only downside was on slippery hard-packed tracks where the YZ would spin up easier and was a little harder to control when it really starts making power in the mid-range. Some preferred the smoother build-up of the stock pipe here. Or at least running the stock muffler which tames the PC pipe’s increased surge by about 50%.

We ended up getting the best performance with the stock jetting setting in California at tracks in the 1000 FT or below range, except for adjusting the fuel screw. The pipe toned itself to a blueish brown over time and as long as we kept water repellant oil on it all the time it stayed rust-free. And with an acidic type cleaner you can get that white, like new look again with a little elbow grease. If you don’t like the extra work, the platinum finish pipe (same price) will eliminate the work. The muffler’s packing stayed consistent over the 10-hours we put on it and we suspect it will easily last 20-hours before needing a repack.

Overall this pipe and muffler combination is a winner for the times you want just a little bit more boost from your YZ250. It makes getting over jumps and carrying the front wheel over bumps just a little easier. Heavier riders and those that likes short-shifting really appreciated the increase in power and torque.

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