Pro Circuit Silencer

Two Stroke Engine OEM Replacement 304

Posted by Brad

Pro Circuit Silencer The 304 has been around for a while now. Named for the grade of stainless steel it's partly constructed from, it's also the first silencer Pro Circuit ever built. Intended as an OEM replacement, the 304 was designed to add horsepower throughout the power-band yet keep noise close to stock levels. In the end (huh huh) it turns out to be somewhat louder than stock, but is at least within most imposed track noise limits.

The canister is formed from 6061 T-6 brushed aluminum. Allen-head screws hold the canister to the framework of the silencer to help ease the chore of repacking. This is a good idea; but another good idea is to occasionally loosen those Allen-heads and re-tighten them, as heat has a tendency to lock the threads into place to the point where you might twist the heads right off, if let go for too long.

The end-cap and intake tube are FIM-approved (translated International Motorcycling Federation) stainless steel. The mounting brackets are double-walled, and the packing that comes inside these is E-glass "pillow" packing.

It's important to note the 304 does not have a spark arrestor. This limits its use to motocross tracks and other such controlled riding areas. Without a spark arrestor, you can receive expensive tickets if caught riding on regulated and maintained trails, and most enduro races prohibit bikes without spark arrestors.

Also check out the FZ6 dual exhaust kit by Two Brothers Racing.