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/126343
width hub front brakes. T his past year's conical front bra ke just wasn 't up to the tas k of slowing down the RM -400 C without a five finger death ~ip. The new full width front brake may add a little more weight , but it can't be helped , considering the bikes are now going faster as suspension and powercontinues to improve each year. , It wou ldn't be fa ir to tell you , though , that Koji's RM was indeed a completely stock model. Whether the fact was that you don't race Trans-AMA with a completely stoc k model and expect to win , or that certain production items like the suspension components weren't available wasn 't made known to m e. But Koji 's bik e used works Kayaba suspension components to give it 12 inches or travel a t each end, and there was a liberal amount of titanium bolts and fitt ings to reduce weight down to 222 pounds. That's just one pound more than Danny Laf'orte's RN at 221 pounds. The production RM -400 N will come with Kayaba air/spring production forks offering 11.2 inches of travel. We only have to look at past RM model forks from Ka yaba to know that despite the in crease in travel , they will probably perform only adequately. Better pro caliber riders will want to modify them to improve damping and travel , or may want to re place them completely. Su ch has always been t he ca se with J a panese production forks . The rear suspension now comes with 11.8 in ches of travel provided b y the normal production Kayaba - deCarbon type sho cks with external reservoirs . This is both good and bad. Good , because the Kaya bas are pretty decent shocks in both reliabili ty and performance when set up properly. Bad . because if the damping and the spring rates of the stock Kaya bas don't suit you , there isn't too m uch you can do about it short of ch angi ng to another brand of shocks which offers you some tunabil ity . This has a lways been a problem with the RM 's, since Suzuk i has never offered own ers th e choice of optional rate springs , Hopefully, th is problem will be corrected with th e 1979 RM ' models, because Suzuki is presently consid ering offering optional spring ra tes through th eir accessory division . The only thing holding them back is th e cost / p ro fit fa ct or to be co n 'sid ered , but with optio na l springs ava ilable , Suzuki would cert ai nly be able to offer Ka yabas as replacement shoc ks for other brands of motorcycles as well . While we're on th e su bject of Suzuk i owners tu ni ng or mod ifying t heir bik es, I might mention that there is no w a Suzuki Ra cing Service wh ich RM and PE owne rs ma y call for tec hni cal info rma tion on their bik es. Ph on e Sharon . the recept ion ist at U.S. Suzuki, 215/921 ·4461. a nd ask for th e rac ing se rvice de p artment. • As mention ed p revio usly, the suspensio n com ponents on Koji's preproduction RM -40 0 N are not the units wh ich will be on th e bik e when it is rel ea sed , but are regu lar Suzuki factory parts. T he forks are 12.0 inch Ka yab a a ir/ sp ring forks and the shocks are the p ro tot ype Ka yaba a ir! sp ri ng units whi ch m ay be avai la b le for sa le within th e next yea r. One othe r major cha nge from wha t is on Koji 's bik e . and what will appear in producti on is th e rear brake. T he fin al product ion model R M's will have a much more rel iable and easier to m a intain rod ac tiva ted full floating rear brake along with a steel torque arm instead of Koji's lighter aluminum arm . T here will be no loss of braking performance with the rod _ activated rear brake , and braking feel and response will actually be increased. When it com es down to giving you a riding impression of Koji 's RM-400 N, the report wou ld be much the same as the one on Danny La Porte's RN 420 ·78 from last week, since bo th Suzukis are nea rl y identical. They are the ultimate in a good handling, well balanced, and powe rful , yet manageable works bi ke . At th is time there is no production b ike avai lable th a t can ma tc h the m for ha ndling and performa nce . But since I d idn't ha ve a complete R M-400 N to eva luate, I' ll have to go out on a limb and predict that the real prod uction bike, when it does become available in J anua ry, will differ from the works bike in that the suspe nsio n won 't work as well , a nd the weight will be about 5 po unds heavier. Depend ing upon the caliber of rider you are a nd your pocket book , you may want to make m odifications to im p rove or re p lace the R M·400 N's stock suspension to bring out the full potential of the bike . The bike is so good it deserves a comparable sus pension. From the moment you firs t set eyes on it and see the new 417cc works type engine , longer suspension , bolt-on cast type factory foot pegs and completel y detachable kickstand m ount ing bracket, you know the new RM·400 N is closer to a works Suzuki than any RM which came before it. And like the original RM of three years ago, th e new N models for 1979 will once again leave a winning mark in the sport of motocross . • 0') CN s-. QJ ..c e QJ > o Z Except fo r being aluminum inst ead of magnesium. th e RM engine is a direct copy of t he works 420cc RN engine. The swingarm is t he same as on the works RN models and is made of extruded aluminum fo r strength and weight saving advantages . Specifications Suzuki RM-400 N Engine, , , . . . . . , . . Two-stroke. Power Reed case induction Displacement . . , , , , , ,, 417cc .~ Bore x stroke ,' ",.,. ao.Omm x 83.0mm Compression ,..,, ,, , . , .. ' 7.0:1 Carburetor , , . , .. , , , , , . , . , , , .. Mikuni VM36SS IT Transmission 5-speed constant mesh Forks . . . . ' Kayaba oil dampened air/spring adjustable. lS . . 11.2 ins. travel w Rear. , . , .. , , , , .. . , Aluminum swingarm. Kayaba reservoir I~ gas/oil shocks. 2 dampening adjustments. 3 preload settings. 11,8 ins. t ravel Ground clear. , , . , .. , , , . , , . , , ; , , . , . , .. , ... , . , . . . 13.8 ins. Tires, , ,,,..,, , , . , 3.00 x 21 f ro nt . 4.50 x 18 rea r ,, , , , , . , . . , .. , , , . , , , , , . , . 2.2 ga l. Fuel tank ,",A Wheelbase 56.9 ins. Dry weight . , , ,,,: , , , . , , . . , 223 lbs, 21