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/126006
Sound tips for Trans-AMA entrants fromMIC -Super qua lity 50% Cotton. 30% Polyester ! - Knitted neck & arm tr im - Dark cartoon with red lettering -Approved by Papa Wealey -Order yours today for immediate delivery - no waiting The Sound Committee of the Motorcycle Industry Council (MIC) , made up of engineers and technicians of several manufacturers, developed the test procedure adopted by the AMA for the Trans-AMA events. The MIC is concerned that all . manufacturers, riders and officials have a full understanding of sound testing techniques and instrumentation. Privateers in particular may not have the p revious experience and equipment necessary to be ' sure they meet the rules. Here are some tips fro m MIC. The AMA will e nforce a new noise regulation (11 0 dB(a)) for the Trans-AMA but the test p rocedure is different fro m t he one contained in the 1975 rule books. The p rim ary di ff erences are a cl o ser m eas uri ng di stance and method of determining test RPM . Te st RPM will be determined as follows: Supply limited-Order fast! Jus t fill out, rip off, & mail to: Cycle News Products PO Box 498 , Long Beach. CA 90801 I I -------------------------name is I Street Address I My Before the noise . test, one of t he following facts must be known about your motorcycle: the red line, the power peak RPM , or the stroke in millimeters. You will be required to operate your own m o t orcycle during the testing. Some words of caution: the sound level of 110 dB(a) with a + 5 dB(a) to lerance is stricter than the old AMA test of 92 dB(a) at 50 feet because the ne w measurement distance is only one-half me ter (20 inches) . You should check your motorcycle before going to the races. Yo u 11 need to lo ca te a good so un d level meter, someone who can operate it properly, and an accurate tachometer. A shop tach is a good idea. For actual testing, both on your own and by the AM A, note the following precautions: 1. There must be a 5 meter (16 ft.) clear area around you and the machine. The tester should be the only other large object within the space. Do not test next to a van or beside a building. 2. Watch out for clipboards, etc. near the microphone as such objects can reflect sound and increase the sound level. 3. Do not use a wire coat hanger or other vibrating material to hold the microphone 20 inches away. 4. Check your machine for vibrating noise makers. It may not be muffler noise that put you over 110 dB(a). 5. Type 3A noise meters are sometimes several dB(a) over or under a Type I or Type II meter. AMA will be using a Type I mete r at the races, You should locate an equally accurate meter for your testing. Based upon some preliminary m an ufact u re rs te sts, your stock muffler m ay not be adequate . If you fear that you are over the allowable sound level check with a reputable accessory exhaust manufacturer and verify your fi ndings. Allshould have sound testing equipment and will probably want to help. Finally , the MIC is offering a $100 per race contingency to the lowest noise level among the top 10 finishers. If you can get your machine super quiet and still have horsepower - go for the extra cash. Good luck. See you at Adan tao State I 1. 50% of red line if there is a tachometer, or 2. 60% of power peak RPM if it is published, or 3. 306,000.;- stroke in mm. I I want _ _ [ 1 small I I I L ... I Zip [I medium ~'* 1 large Tee-5hirts I enclosed 15. 95 for each Shirt (California residen ts add 6% sales tax) ......... ~H HUSQVARNA \!JI~ PARTS I I I I .......:JIIIIII [l extra large - new Chain Tensloner Shipped anywhere in United States. Send complete frame and engine numbers, model, year, engine size. part description or old part . Parts prices on request. T&O"Vamaha 24020 Narbon ne Ave. Lomita , CA 907 17 21 3-534-231 1 AIR FORKS OR SPRINGS The Front End Kit t hat works either W 1J'( pr your Money Back I Designed for RACING over rough terr ain. WiII llive you a ride second to none I No modifications. just bolt in the new units. 8" of travel - Kits for: CZ red or black frame; Yamaha Small leg 125/1 75 MX, Ya maha Enduros , MX . YZ and Monoshocks; Kawasaki KX 125, KX 250, KX 450, new KX 250/400; Suzuk i 250/400 & RM '7 3 - '75; Bato rs. Dealer or Direct Send for Free Uterature TERRY INDUSTRIES P.O. Box 13 21, Hesperia, CA 92345 714-244-3139 Extra heavy dut y tensioner - precision manu factu red with Tef l on rolle rs to resist wea r und er ex treme use. Dual function: spring loaded roller keeps chain taut and the angle of the moun t acts as a chain guide and prevents mud . o r brush from getti ng into the rear . sprocket . Heavier d uty with closer toleran ces and higher test springs th an ot hers on the market. 821.95 For info contact: -Cf' ~ 8423 Rosemead Blvd. Pico Rivera. CA 90660 213-869-7346 Dealer.& Dist. inquiries invited cao-am ~. /'" I r1l \ ' - ' !'. " : ! l l '. I" >- <":,)C 1', c ompetition service. inc 12 4 4 N G.1 f 1c y , S ,lrl P e d r o . C A 9 0 7 3 1 :?1383 1 1 2l9 39 )