AMA Flat Track Releases Approved Exhausts List for 450 Singles Series Racers

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Kenny Coolbeth, Jr. can be seen working on changing a tire for one of his #2 Honda CRF450s in his pit area at the Gas City Short Track round of the AMA Pro Flat Track K&N Filters presented by Motorcycle Superstore.com Grand National Championship Series in June of 2010. The Bettencourts Honda/Jason Perry/
Arai/Fox-sponsored rider won the '07 AMA Flat Track Singles Series, and his prowess on the Singles is just as good as it is on the Twins Series bikes. He will be rolling out a new machine at Daytona in just over ten days, and will be astride a Chaplin Kawasaki-sponsored KX450 at the '11 Singles Series events, after having been associated with the Bettencourt's Honda for several years. The King of Cool is one of several riders switching from the Honda 450s to the Kawasaki 450 for the upcoming season, along with Joe Kopp and JR Schnabel, among others. They will be joining 2-Time Singles Series Champ Henry Wiles on his Jones Bros. Kawasaki and Werner Springsteen Kawasaki's Bryan Smith, who both campaigned the KXs during the 2010 season.
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AMA Pro Flat Track Competitor Bulletin #2011-04

All AMA Pro Flat Track Competitors

Subject:

Approved Exhaust Systems for 450

The ruling for sound levels for 450 singles in AMA Pro Flat Track has been, and will continue to be, 105dB. This is measured on the "A" scale at a distance of 20 inches at a 45 degree angle to the exhaust tip. All sound testing is done in accordance with SAE J1287. Bikes are tested at ½ the rated maximum rpm. This is typically 4500 to 5500 rpm depending on the model.

Several fairground type venues have expressed concerns over the excessively loud sound levels in the singles class and have received complaints from nearby residents. AMA Pro cannot be put in a position of losing desirable venues due to competitors’ non-compliance with the rule book.

Over the past two years the technical staff at AMA Pro Flat Track has done random sound testing and has suggested and advised non compliant riders to make suitable changes to overly loud exhaust systems. Starting with the AMA Pro Flat Track Series opening round in Daytona, any riders that violate the sound limits in the rule book will be disqualified from competition.

Per the general equipment standards in the 2011 AMA Pro Flat Track Rule Book: Exhaust pipes and

mufflers must be used and be securely attached together and bolted to the frame.

Mufflers must have sound absorption mechanisms or packed baffling.

Exhaust system with no mufflers and open ends (no end cap) will be refused in tech and not allowed on the race track. Do not attempt to go through tech with an unmuffled motorcycle. It will not pass tech. Do not attempt to go onto the race track with an unmuffled motorcycle; you will be disqualified from the event.

AMA Pro will make sound testing available as time and personnel allow previous to the event, but is under no obligation to pre test motorcycles. It is the responsibility of the competitor to arrive at the event with a motorcycle that is in compliance with the rule book.

Below is a preliminary list of approved exhausts. More will be added as time and research allow. Contact AMA Pro Racing for suggestions on additions to the list. All pipes used in AMA Pro Motocross and AMA Supercross must meet a 96dB rule and as such are eligible for AMA Pro Flat Track.

FMF Pro Circuit Yoshimura Akrapovic Jardine

Leo Vince Two Brothers Vance and Hines D&D Low

Jemco w/ SuperTrapp adapter SuperTrapp

Be advised; just because a pipe is on this list does not mean it will pass sound tech with YOUR particular engine configuration. Once again, it is the responsibility of the competitor to arrive at the event with a class legal motorcycle.

Thanks to AMA Pro Flat Track for this updated technical bulletin!

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