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/125813
... " 1 N .... Ol Ol ~ w Z W ...J U >U by Art Friedman Back in July we tested Yamaha's 1972 250cc offering, the DS-7. We were so impressed with the performance, handling, braking, and reliability of die machine; that when a friend said that he wanted to buy a machine of that displacement range, we steered him toward the· D5-7. The 1973 Yamaha 250 is designated the RD-250, and when we received ours we turned to our friend's DS-7 for comparison.· The two most important changes incorporated in the new 250 Yammie are reed val ves and a six speed transmission. Yamaha has used reed valves in its dirt bikes with an eye on improving low end power. They call the reed valve system "torque induction", but in the new RO-250, "torque reduction" would be a more appropriate title. With the reeds and the new seven-port cylinders (the DS-7 has five ports), the machine is much peakier. It is down on power to the OS-7 up to about 4000 RPM; they are about equally potent between four and six and a half thousand; but at about six-five, the RD-250 really comes on, and has more power right on up to its 8,300 RPM red line, which is 300 RPM higher than last year. The six speed box is a nice addition for road racy types who like to shift a lot. It also helps the peaky RO-250 get off the line without too much dutch slipping, and it closes the gap between first and second wbich is useful with the narrow power band. I t also gives you a choice of about three gears in normal use. The only time you need a six speed is when you are flogging. down a mountain road or when leaving a stop ligh t. The peakiness is most apparen t when pulling away from a stop. The other noticeable changes in the RO-250 are a complete restyling. The front end has been re-thought, and has gotten different looking forks, a new fender arrangement, and a dash-board type of instrumen t panel. In the dash-board is one of Yamaha's new safety features. It is a ligh t that indicates that the brake light is on. It tells you that the brake filament is burned out or, as happened to us, that one of the switches isn't working., Another good idea along this line would be a light that came on when your taillight wasn't working; it might keep somebody from getting rear-ended. One of the styling addendas is a chrome cover on the bottom of the triple clamp, an item which was obviously inspired by Harley-Davidson's Sportster. The tank has received a new paint scheme, and the side panels have been ' restyled. We didn't like the old chrome accent pieces on them, but we like the false louvres even less. Fake louvres have been around on bikes for a while, and we never liked them. These are particularly obnoxious because they seem more Detroit-inspired than any others we have encountered and because one fell off. . The seat has gotten a covering with more ugrain" and the rear fender has gonen an extra wrinkle. Another change is the exhaust system which has been made two piece, a change which runs against current trends. It seems to be an unfortunate change, too. because the righ t pipe on ours leaked at the pipe-muffler joint. The firs t thing we discovered when we received the machine was that it wouldn't start. We were aided by a member of U.S. Suzuki's service department who happened to be picking up his paper. Even after he got it running, it had this rather unpleasant habit of fouling plugs. In fact, it was ridden. home that eve,ning on one cylinder. . Eventually, we discovered that the starting plunger wasn't seating. Some. tomfoolery solved that problem, but it still persisted in fouling plugs occasionally when cold. It could be that there was still something amiss with our machine, but a thorough check out by our resident wrench revealed nothing. The RO-250's engine had one more unpleasant characteristic. It gave out a piercing shriek at freeway ~eeds. This was probably due to the reeds, as the whole sound of the machine was different than the OS-7. Because of the peakiness, the plug fouling, and the ear-twisting shriek, we feel that the OS-7 engine was preferable. The RD engine will suit those interested in co mpetition, either formal or informal, better than the five port version. Ideally, however, we would like to see the old engine coupled to the six speed transmission. In other areas the RD-250 shines. In our OS-7 test we said that Yamaha was expected to install a disc on their 250 as they have on their 350. They didn't, and it is for the better. The drum on the RO-250 is better than a disc. It has all the power that one could ask for and has excellent feel. It is also lighter than a disc. Its only disadvantage is that it may require a shide more maintenance. The suspension has been beefed up a bair. The added stiffness hasn't hurt the tide characteristics any, and it offers sligh tly more clearance when cornering. Ground clearance was a problem with the OS-7. There still is a trace of high speed oscillation during cornering at near the cen'tury mark. The friction DETAILS TOP: The engine is beautifully stYled. The little red line around the Yamaha logo is gone and the carbs have been painted black. The fake louvre on the oil tank isn't so neat, especially since one fell off. CENTER: The "dash board" is new as is kill switch (right handlebar! and locking gas cap. BOTTOM: Seat lock is new and will protect your tools unless someone comes along with a screvv driver. Lifti,ng handle is also new. steering dampener is' gone (as. on the Hondas) which should indicate that Yamaha has a l(ood deal of faith in their frame and suspension. As on the DS-7, the frame is the same pattern as the Yamaha road raeers_ JAPANESE ARITHMETIC ENGINE: Type Bore x stroke Two cylinder, air cooled 7 port 2 stroke with reed valve induction 54mm x 54mm g~s~~~:s~:~t,~ii~'::::~: : : : :: ~ ~: ::: ::: ::::: ::: :: : : : ::::: :::::::: ~: 27~~~f Horsepower More than last year's claimed 30 Camuretion , ...•....................... (2) 28mm Mikuni Oil capacity ...............•...•...• _ 2.1 qts. (engine oil) Re.commended fuel ... ~ ..•. ~ .. , ..•............. Lowdead, 73 or higher octane ~~~~~ii~;' : : : : : : : : : : : : : : : ~ : : : : ~ : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :~a.t~~r:K'i~~ Shift pattern _ _ Left foot, down for down, l-N-2-3-4-5-6 OTHER STUFF: , ~~~t:'" • • • •:•·••:•·.•• • :·.:• •:•·••·•.• ,". ,~;lli Gas mileage during test Milesrecorded during test Suggested retail price , _..•......•....... , •.......... 3540 MPG _ 1023 , •......•............... $759