Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126773
~ tJl z ... w \ e 0 II' " ~ > III tJl 0 ~ 0 ... :I: ~ 00 0") .....-4 ~ 0 C\.f V I:: =' ~ By John Ulrich Yamaha's RZ350comes to the U.S. equipped with a complicated emissions control system of air injection pipes and catalytic converters. It's still fun to ride, but the extra equipment adds about 10 pounds to the bike and detracts from performance. We'll be honest: we like per- Stock U.S. RZ350 with Rse pipes: 12.57 sec. @ 106.25 mph. Off with the slow. on with the quick: 18 RZ3S0 pipe and modification co .arison formance more than we like clean air, and, thanks to a wonderful thing known as the First Amendment. we can tell you how to make dirtier air and get more performance, Environmental Protection Agency be damned. The quick route to more power is to bolt on exhaust pipes. That's especially true if you've put street miles on an RZ350, because carbon accumulating in the pipes will reduce performance significantly. A good running RZ350, for example, will run the quarter mile in 13.20 seconds with a terminal speed of 99 mph when new. But the test bike seen here slowed down to run strings of 13.50-bracket passes at 97 mph after 2000 street miles. So we bolted on a set of Toomey Racing pipes. The Toomey pipes are designed and built by Stuart Toomey. who wrenched on Freddie Spencer's NS500 in 1982, working with Erv Kanemotp in Europe. The Toomey pipes are lighter (5.0 pounds each, compared to 13.00 pounds each for U.S.-legal stock pipes) and more stylish, looking like, well, racing pipes. They have alumin urn silen<;ers, and .the sile{l~ers can be rebuilt by removing a snap ring. The chamber hangers are two triangulated steel straps welded to the expansion chambers on the end and both sides; and there's a center-stand stop built onto the left pipe. II they're styled Hke race pipes, they're also priced like race pipes: $300 per set. With the Toomey pipes installed and with stock jetting, the RZ350 ran 12.67 sec. @ 104.89 mph. After the standard 230 carb main jets were replaced with 370 main jets and the manifold boots leading from the airbox to the carbs were removed, the stocker with Toomey pipes ran a best of 12.61 sec. @ 105.50 mph, with a close spread of 12.6-bracket runs surrounding that best pass. With the Toomey pipes the RZ became more wheeJie prone; best power was made around 10,000 to 10,500, and the bike stayed on the power band when shifted at 10,000 rpm. On the other hand, the Toomey pipes sounded like race pipes, loud, with a sharp bark as revs increased. Ever stand behind a TZ250 screaming away from a dead start? That's what the Toomey-equipped RZ350sounds like. The next stage was to try a set of RSC Hyperformance pipes made in Japan by Noguchi, a well-known Yamaha hop-up company. The pipes seJlJor $350 and have riveted-together