Cycle News - Archive Issues - 1960's

Cycle News 1968 08 29

Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles

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Page 23 of 23

Da}{tona. , Laconia. osport. flASH: Ron Pierce swept to victory In the 50 Mile Amateur Road Race at Indianapolis on August 4th aboard a 350 cc YAMA HA, defeating 500cc and 150cc machines on the fast horsepower course. Keith Mashburn contllfiled his winning ways with a double headed victory at Ascot Par1< winning the Flattrack Novice Main Event on Friday, August 2nd and the TT Novice Main Event on Saturday August 3rd. - ~ . "' ''~. .. ..' -; ~. .. .h ., '\. , -;" . :" '.~ ". When we first announced 5-port power, we got mixed reactions: "Hmm really . .. good for you yawn." : Since then , we've visited a few race tracks. :'" "' 1 (Daytona : 7 out of the f irst 10 places in the 250cc·Race. 2nd and 3rd in the 200 Mile Classic against machines twice our size. Laconia: 8 out of the first 10 places in the 75·m ile Expert. 250cc Final. Mosport : 1st in both the 250cc and the Open class.) Suddenly, everybody's interested. - Here's the difference with 5·port power: In an ordinary 2-stroke engine. burnt gases at the top of the combustion chamber keep the fresh charge of fuel from completely filling the chamber. Some of the fuel goes straight out the exhaust port. s-port power puts two extra ports at the back of the cylinder. Fresh fuel swirls up into the top of the chamber (not out the exhaust) . All the burnt gases are pushed out . The chamber is completely filled with fresh fuel. YAMAHA~ INTERNATIONAL CORPORATIO N · S I N C E 18S7 , ..

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