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Yoshimura RS-7 Silencer
Racer 450 Magazine
July, 2007

Yoshimura RS-7 Honda 450R

You may have seen these pipes around at the nationals; Joe Byrd runs one of these in complete system form. They’re quite popular and quite pricey. Does it all add up? We decided to try one on our test bike, here’s what we thought.

We loved the look of these pipes, especially the yellowish, greenish colored magnesium end cap. Since we had not yet tore into the engine on our bike we opted for the slip on silencer only version, we thought the complete might be too much. It ended up being a good choice.

Mount up was simple, everything fit well and we were quite surprised by just how high the quality of this pipe’s construction was. Believe us when we say this isn’t just the same silencer as the less expensive models with a magnesium end cap. We opted to go ahead and remove the spark arrestor since our ATV would primarily be used only on a track or on our own property.

Like all Yoshimura pipes this one sounds awesome. It won’t disappoint. It was actually quieter than we had anticipated and reinstalling the spark arrestor would bring the noise levels down even lower if needed.

The new 450Rs have quite a snap in the lower throttle range, after installing this silencer that was cut into slightly. The silencer did add some mid and a whole lot of top end response, so the trade off wasn’t bad. We did feel that even the silencer only option might be releasing so much air that this could be hurting us. We set up our 450R by removing the air box lid and swapping to a 180 main jet with no other carburetor changes. The jetting was dead on but we’re sure a little more power could be found with some air/fuel screw adjustment.
Yoshimura RS-7 Honda 450R
Visit Yoshimura-rd.com

At this point we were satisfied with our new silencer but were not overwhelmed. At the time of installation our 450R hadn’t even been through a complete tank of gas. As we rode we noticed the power steadily increased in the low end as the engine broke in. Although we are confident that going to an aftermarket piston with a more “true” compression rating would really bring things to life the engine/silencer combination really is snappy everywhere in the power band and puts a smile on our face. The sound has only gotten better with time and we may even move up to the full system once our engine gets broken into.

Our Thoughts:
This is a well put together race pipe. It challenges any other pipe on the market for construction quality. It could be used for trail riding since it does include the needed spark arrestor that many riding areas require but make no doubt that Yoshimura was thinking of competition when this silencer was built. It may actually be a little over engineered for a stock engine, meaning, an aftermarket piston won’t hurt but if you go to a full race compression like 13:1 or 14:1 we’d go for the complete system.

You also may notice that we have color matched the end cap to our black color scheme even though we do love the factory pipe’s end cap color, this is not a factory option.

Product provided by: MX Midwest

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