Report From Japan
REPORT FROM JAPAN
JACK YAMAGUCHI
YAMAHA TX 750 FOUR-STROKE
Yamaha recently introduced an all new four-stroke 750 vertical Twin that should provide the basis for an excellent flat track mount.
Like the 650 Twin currently in production, electric starting and a hydraulic front disc brake are featured. Styling is also similar, but the paint scheme and detail appointments differ.
SPECIFICATIONS:
Overall Length-88.2 in., overall width—36.4 in., overall height—46.6 in.
Wheelbase—58.2 in., ground clearance—6.4 in., dry weight-462 lb.
Top speed—120.9 mph, engine— Single Overhead Cam Parallel Twin, displacement—743cc, bore x stroke— 80x74mm.
Compression ratio—8.4:1, maximum bhp—63 at 6500 rpm, starting system12V electric, ignition—battery and coil, fuel tank capacity—4.3 gal., Oil tank capacity—2.7 quarts.
Gearbox—five-speed, gear ratios—1st, 2.461; 2nd, 1.588; 3rd, 1.300; 4th, 1.095; 5th, 0.956.
ALL JAPAN CHAMPIONSHIP MX
The ’72 MFJ-organized All Japan Championship MX Series raised a curtain with the first round held on a specially prepared circuit north of Tokyo. The meeting was promoted in rather terrible weather conditions, but more than 840 machines entered, attracting some 30,000 spectators. Both were new records for this type of sporting event in Japan, reflecting growing enthusiasm for motocross.
Interest focused on the senior 250cc class in which Honda entered its newly developed two-cycle works machines ridden by ex-Suzuki aces T. Yoshimura and H. Ueno. However, a Yamaha seven-port “Torque Induction” machine piloted by H. Suzuki convincingly beat all challenges from all other machines entered. He also snatched a win in the senior 125cc race, on another “Torque Induction” Yamaha.
In addition, Yamaha proved to be the most successful make outright by finishing first in 5 novice, junior and expert/junior class events.
SENIOR 250 RESULTS:
1. H. Suzuki, Yamaha; 2. T. Suzuki, Yamaha; 3. M. Takezawa, Kawasaki.
SENIOR 125 RESULTS:
1. H. Suzuki, Yamaha; 2. M. Takezawa, Kawasaki; 3. K. Yajimi, Suzuki.>
YAMAHA’S ’72 MOTOCROSS PLAN
Yamaha formally announced its.’72 plan for world championship motocross recently, though it had been long rumored before. According to the plan, Yamaha will cover this year’s championship series and international events in Europe with Swedish aces T. Hallman, C. Hammargren, H. Andersson, and Belgian star J.V. Velthoven. Greater emphasis will be put in 250cc class competition.
Their primary objective is to obtain technical data through racing, and make use of it for developing and improving production models.
In line with this racing plan, Yamaha recently invited T. Hallman and C. Hammargren to Japan for initial tests on newly developed works machines. Both riders rode Yamaha machines, based on the trail 250 DT Special, over various motocross circuits in Japan. No technical data was released, but both riders looked quite satisfied with handling and performance.
Yamaha also suggests possible participation in this year’s world championship 500cc series. Though they are reluctant to release any concrete details of this plan at the present stage, bigger machines may make their racing debut this year.
HONDA’S TWO-STROKE MODS
As earlier reported, Honda will challenge this year’s national championship series with a team of T. Yoshimura and H. Ueno, riding the newly developed two-stroke machines. Prior to any competition, Honda unveiled the latest ver sion of the said two-stroke machine under the designation of 248cc, 335C.
(Continued on page 136)
For this version, cylinder head fins and exhaust port are fitted on the right side, while the former 335B version has them on the left side. In addition, considerable modifications have been done to the frame. The two-stroke single cylinder engine features a 70 by 64.4mm bore and stroke, and delivers over 30 bhp to the rear wheel. The unit turns in the neighborhood of 7 or 8000 rpm.
Unsparing use of special materials such as magnesium for the crankcase cover, molybdenum for the frame, and titanium for various nuts, has reduced the weight to 184 lb.
Honda 335C Specifications
Engine, two-stroke single cylinder; bore x stroke, 70 x 64.4mm; displacement, 248cc; maximum bhp, 30 bhp plus.
Overall length, 84.4 in.; overall width, 34.0 in.; overall height, 43.6 in.
Wheelbase, 56.8 in.; weight, 184 lb.
TOMS’ JAPANESE TOUR
Douglas W. Toms, U.S. National Traffic Safety Administrator, and his party consisting of traffic safety officials and specialists recently visited Yamaha at Iwata.
Primary objective of their visit to Yamaha was to inspect assembly lines of the Iwata Main Plant and to have talks with the company’s top level staff on the possibility of experimental safety motorcycle development.
Prior to his visit to Yamaha, Toms had sounded the Japanese government regarding the joint project of developing motorcycles, and got a positive answer.
At Yamaha, lively discussions focused on the improvement of motorcycle design and components with “safety first” for riders in mind. As one of the leading motorcycle makers in the world, Yamaha is very keen to give overall support to the project, especially since it has taken definite shape between both governments.
