Reeds - The aftermarket is full of replacement reed petals and cages for all three of the different Super Jet lower ends. The main considerations for alternative reed petals are performance, longevity, and side effect damage from petal failure.
Yamaha employs stainless steel reed petals in all the 6M6 and 61X cased Super Jets. Some of the 62T cased Super Jets came with stainless steel petals, and some with non- metallic "fiber" reed petals. The stainless steel material is used because it has an outstanding flexibility to weight ratio, the metal material seals exceptionally well against the rubber coated reed cages. Regardless of which material Yamaha chose, all the stock Yamaha reed petals offer excellent overall power characteristics. From a sheer performance standpoint, there are no aftermarket reed petals that out perform the stock petals by any big margin. All the stock Yamaha reed petals also offer exceptionally good long-term reliability.
Unfortunately, after enough service time, the stainless steel metal reeds can eventually fracture and break apart. When these stainless steel petals break, and circulate through the engine, they have the ability to cause serious damage to virtually all the internal engine moving parts (pistons, bearings, etc). If a fiber reed petal breaks apart, the engine easily "digests" the material resulting in no engine damage at all. While this reed petal fracturing is not a big problem on stock engines, the added pressures of high performance modification can significantly shorten a metal reed petal’s life.
For most recreational riders, the stock stainless steel reeds (replaced every 2 seasons) are likely the best overall performance value. However for any owner preparing a Limited 2, or Big Bore racing engine, we would recommend the use of non-metallic reed petals. Owners of 62T lower ends can simply purchase the stock Yamaha fiber petals used in the later models. For 6M6 and 61X case owners that wish to convert to fiber petals, we recommend the reeds from Carbon Tech. In this application, the Carbon Tech reeds appear to offer the best aftermarket mix of good performance, good longevity, and good cage sealing. Carbon Tech offers different material tensions for their reed petals. The "LT" (low tension) petal should be used in Limited packages to maximize the low end improvement. The "HT" (high tension) petals should be used in all other modified applications. These petals should be replaced annually in recreational engines, and inspected every 15 operating hours in racing engines.
About Reed Stuffers - "Reed stuffers" is an industry term that describes a plastic insert that smoothly guides the incoming mixture from the round profile of the carb throat, to the rectangular profile of the reed cage. The net result of reed stuffers is usually a small improvement in overall acceleration and response. Stuffers generally have no effect on peak rpm. The '96 - '99 62T engines are the only Super Jet engines that employs a design that can utilize reed stuffers. Reed stuffers are not required on the 6M6 and 61X engines.
