Cycle News - Archive Issues - 1970's

i ex ical i Chamber of Commerce and the Baja Racing Assn. ... AiJI\PllI 8~GI~8~~~~ Desert Race Mexicali to San Felipe 225 miles March 6, 1976 . Novice * Amateur * Expert * Powder Puff 0-125 126-250 251-0pen limited to 500 entries ' Entry fees: Novice, Amateur & Powder Puff 550.00 Expert 5100.00 - 50% payback 50% payback Ind ust ry awa rds in all classes Send $25 .00 deposit with any entry form - balance due Mar. 1st. Start ing position det ermined by order of receipt of entry. If you would like to help mark course or man a check please write or phone. Thank you. Award Donors Casa Grande Restaurant Va lvoline Bel Ray K& N Filte r KTM Cha mp io n Spark Plug Krizrnan Spark Arresters Cycle News Mulho lland Shocks Den selu be Super Chain Pen nzo il . Electro Helmets Preston Petty Products Fi1 t ron Gu mou t Pre m ier Helme ts Hoda ka _ Malcolm S mit h Rac ing Product s Un i Fi lter Hustl er Gas Tanks Imperial Honda Hotel EI Cacha n illa Hote l Lucerna Imp eri al Count y Yama ha Desert Kawa sak i Webco Jf Use of extra large washen on the muffler support bracket helps in reducing breakage. Safety wire all shock bolts. The dust cover plate on the rear hub seal is brazed to the axle spacer to keep it from sliding away from the seal. ~J secret hare & hound type course. 5 bikes start pe r m in. L ights not reQu ired. Not more than sIxty miles between gasstops. • ~ [lMI OO~~~~L VI~ Box 1803 Calex ico , CA 92231 Phone : (903) 762-2794 ask for Raul ~.. . BRENT HEIIII I BII/IIIll -'"11 · @ RIVERSIDE INTLftACEWJIY!@ • • • • • ENTRY $14.00 MA IL, $25.00 POST. ENTRIES CLOSE MARCH 7 FOUR l OG-MI LE RACES · DISTRICT 37 POINTS AMA SACTIONED • COMPUTERfTV SCORING PART ICIPATING AND FINISHER PINS • GBGP DECAL RIDER NUMBERS FURN ISHED • BIKES MUST BE IMPOUNDED PRIOR TO RACE • NEW COURSE • OVERNIGHT CAMPING • SPECTATORS $5.00 • CHILDREN UNDER 12 FREE • MAI L GBGP ENTRY FORM (A V A I LA BLE AT LOCA L BIKESHOP ) TO : GREAT BEAR GRAND PRIX (WITH TWO SASE) P.O. BOX 6026 • ORANGE, CALIF. 92667 The engine APRIL 3 & 1I, Iq7b BIGGEST MOTORCYCLE EVENT OF THE SEASON! Save the economy-.Buy something today! jM fisltbAck's YIMAIIA"!?IOflr.A:MJ.\ @ 16 (714) 822-2252 9008 Sierra Ave., Fontana, Ca. Goodyear is Carroll Shelby 21 3-538 -291 4 who failed to jet their b ikes out properly suffered detonation and risk seizure. Suzuki rectified this problem by going from a QO needle jet to a Q4 as standard equiprnen r, We would suggest these jetting changes, bu t cJ1anges should be suited to your lo cal conditions and riding style. RM 370: 320 main jet, Q4 needle jet with the clip in the middle slot and the standard 50 pilot jet. RM 250: 310 main jet, Q6 needle jet with clip in the mi ddle positi on and the standard 50 p ilo t jet . (Remember these are suggested by Cycle News an d not U.S. Suzu ki so carefully set up your carburetor an d test the bi ke un til yo u find t he right setting. ] Since th e RM s wer e designed for moto c ro ss , th e Mikun i carb ureto rs which tn ey u se don ' t idle whe n tne throttle is shu t off. If you are using a RM fo r hare scrambles or.woods riding you mignt want 10 cnange to a 36mm Mikuni which has an idle adjustment. Experiments o n the RH 250 an d RN 37 0 works bikes h ave found that a larger 38mm Mikuni carb will increase torque at lower rpms without hurting top end horsepower. Inside the throttle assembly upper cap, the piece where the throttle cable enters the throttle assemly, there is a place where the inner throttle cable rubs every time the th rottle is turned. With so me use, the inner throttle cable will begin to fray, then hang-up. Use a sm all round file to cu t down the aluminum where the throttle cable rubs across the inside of th e cap. / The RM 250 an d 3 70 engines are extremely p owerfu l while retaining a h igh d egre e of reliability . Except perhaps for blueprinting th e p or ts on the 250, you'll w an t to leave b o th engines tock, As mentione d earlier, the RM engines are perhaps m ore adv anced an d more powerful than the RH an d RN works en gines, One slightly disconcerting thing ' abo u t the RM engine is th e rig ht side clutch case which visibly m oves wh en the clutch is engaged. This case movemen t could acco unt for some clutch d rag if you allow misadjustment to occur. On ly possible cures for this minor problem can be suggested since none have been tried. Heliarc welding a small aluminum plate might stiffen the clutch case, as might several beads of weld in the area. In all this is a minor annoyance which the majority of riders will never notice unless they were opting for the utmost in high performance. Miscellaneous New, st ronger rear b ra ke sp rin gs which ' h a v e the p a r t n um ber 55420-411 00 are now available an d found on all b ikes after RM 250·138 0 1 an d RM 37 0·1312 6. The old bra . sp ri ngs will break an d perhaps j am b etween th e shoes an d th e drum . Suzu ki also offers an o ptio nal magnesium rear hub and rear bra ke panel. These two i terns will lo wer u nsp rung weight on t he rear whe el and increase the strength of the uni t, at a co st. Suggested rear t ire for h ard tracks is a Metzeler 4 .5 0 with a Trelleborg 4.5 0 fo r soft dirt or sand tracks. O n the RM 37 0 change the ign ition timing fro m the factory se tting of 4.1mm. Before top dead center to a slightly m o re retarded setting of 3.8 BTDC. This will give the engine m ore low end power and prevent high rmp detonation which could lead to overheating and seizure. On the RM 250 set the timing at 3.31 BTDC . Conclusion All this m igh t seem like a lot of work to make the RM 250 and RM "37 0 raceworthy, but in effect most of the things we talked about should b e con side red general main tenance an d preparation for any m o tocr oss bike. The fact that the RM Suzuk is are one of the best motocross bikes on the m arke t today, price not even being considered, y o u can expect most otner b ikes to require a lo t more attention. • Where to get items mentioned Thor Enterprises 6895-H Osl o Circle Buena Park, California 9070 1 (7 14)52 2-4571 Motocross Center 643 E. Arques Ave. Su nnyvale, CAli fornia 94086 (408) 245-6060 Basset t Racing Produ cts 2222 West 2nd Street Santa Ana, Cal ifornia 92703 (714)543-1127

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