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/125864
The bike will be fo r hillclimbs and fas t des ert here in Wash ington. What I wo uld like to know is: (I) would you consider slipping m e a little good advice on what else I might try to gain more power from th e TM 400 ? (2) I kn ow that y ou pr obably make th e best exp ansion cham bers that can be had. Will yo u mak e one fo r m e ? ( For the reed valve m ot or.] (3) If so please send me the co st and I will send a check now. R onald Edie Washington fn !J IliQ -= =- IliQ g g ~ t"- O"> Got a te chnical problem that needs expert advice? Send queries to "Ask E.C." c/o Cycle News. Your reply will appear in the paper within a few weeks. Hard questions may take a lit tle longer to answer. - 00 u C ::l ...., J In RTI desperation Torl ief Hansen graphi cally demonstrates that he did have the th rottle wired open t o win th e British 25 0 Grand Prix. T. Hansen handstands to GP win, Moisseiev points to lead, and Pomeroy misses the plane St ory & ph ot os by Martin Christie More Suzuki 40 0 power CHALTON, EN GLAND,JUNE 2 In a sensational finish to one of the most dramatic Grands Prix ever, spectacular Swede Torleif Hansen (Kaw) took the final chec kered flag, up on the pegs with both hands raised in a vict ory salute, then proceeded to do handstands up on the bars passin g the 28 cheeri ng crow ds. He won that race, obviously, and was second in the first m o ta behind Belgian wonder Harry Everts (Puc). In both races, flat rear wheels in the last few laps robbed victory from tw o men who looked ready for it. In the first m o ta , Vic Allan (Bul) ; in the second, Jaroslav Falta (CZ). Jim Po meroy went out of both motos in England. In the first, it was a flat rear w heel and in the second, after falling twice . J im was less than happy on the to ugh English track since he had only the Sunda y morning practice session to learn all the right turns. "It's just no good," he said, HI can't remember w hich tum co mes next:' Ji m di dn ' t arrive in Ports mouth un ti l la te Saturday nigh t afte r fly ing in from Madrid. He sho uld have arr ived on Friday, hut was delayed by Spanish cus tom s. He 'd gone ba ck t o -Spain afte r the Yugoslav GP , leaving m ech anics Arn ie an d Rubio to take th e bikes to En glan d wbile he co llec t ed all their exp ens e money fro m th e Barcelona fact o ry . When he tried to lea ve Barc elo na wi th the currency he was sto p pe d and I have a 1971 RTJ Yamaha which is t he w orst handling machine ever built. In d esperatio n I moved the rear shocks 5.5 00 forwa rd at the top of th e fram e and 4.750 fo rwa rd at the swingarm. Now the bike seems to handle better, using Thermofloui sh oc ks. N ow the forks are th e obj ect of my next attempt to obtain better handling. Should I disca rd th e Yammi forks? Is there a fo rk kit availab le for a 1971 RT I 360 ? IVhat are your suggest ions? I rid e Hare and Hounds and Hare S crambles. lVes Hu ntley Lan cast er, Calif. Wes, I understand your problem. There ar e a co uple of fork kits th at ar e pre try good. One is made by Poppy Co . ou t in Burbank, p hone number 2 13/8 45- 6 76 6. Dirt Bike did a test on a fo r k kit back ab o u t two months ago and Super Hunk gave me a call when they were doing the test (this was before th e article ca me out) and said they really did the job. I don't know who m akes them but seems like they o nly cost so mewhere around 15 b ucks. What have you got to lose? Dirt Bike's phone number is 2 13/981 ยท2317. Alls port Steens has Ceriani Fork kits for m ost bikes, th is wo u ld be a co m plete fro nt e nd .a nd yo u r local dealer could orde r it fo r yo u, p robably fo r abo ut $150.00. I'd try a fork kit firs t. taken off his flight wh ile officials questioned him abou t his new-found wealth. He had to go to Madrid to ca tc h an other flight, but official s re ckoned he had to see a judge to get a co u r t order al lowing him to leave after his cu rr e nc y sm uggling job (t aking o u t more than his ow n allowed share) . But th e co ur ts don't sit t ill Monday , a n d Bultaco officials had to find a Madrid j udge on his day off to sort th e m allcr out, and get Jim on a plane. Eventually Jim arrived - in London. and Arnie and Rubio had to go up from Portsmouth to get him . After all that hassle, J im was less than happy w ith his performance. Running a GP motocross during the Isle of Man TT in England lo o ks like a bad d eal on paper. Plus the "good" o ld British weather Came d own again, dowsing th e circuit with mists and dr iz zling rain . Despite t ha t, th e GP drew a cro wd of ab o ut 15,000 - one o f t hc bigg est motocross gates for many years here to check out one of the elosest fough t 250 battles in recen t history, an d ma yb e see a Briton up there with t he leaders (an o t he r unfam iliar sight ). T hey wer en 't d isappoin ted! T he new co u rse had been extensively m odified wi th an artificia l jum p and th ree long. loose ascen ts whi ch had a Continued on page 35 After reading your article for so me time I canno t he lp but thin k you know your stuff I am writing fo r your help. I have p urchased a new TM 400 from the Suz uki distributor in California. I took th e motor apart, beveled som e of th e gears, remo ved th e oil pump, (w eld ing up th e area arou nd t he re) , and cleaned up and polished all th e ports. I d id not mak e an y of them bigger, but I did m ill off t he in take side and weld a CZ 400 DH reed valve and manifold t o it. I th en installed a 38m m Jl ikuni. . I also purchased a first over b ore Veno lia pist on fo r it. Th e m otor has not been run as ye t as I am writ ing f or a f rame from Tra ck master. T Ron it sounds like you have things under control. Looking back at some of my layout sheets on 400 Suzuks, I come up with a exhaust time of 87 degrees and 3 0 degrees o n the transfers. For what you are going to use the bike for I would open the eyebrows up just a lillie then polish the port real good, but I wouldn't raise it any. So the cy lind e r will fill a little better raise the lead ing edge of the transfer ports .0 5 O. This will give you a 2.5 degree lead, and will help pull in a little more m id ran ge to rq ue. As fo r the reed pipe, no p ro ble m, put yo u r bike in a box an d sh ip it to m e. Bu t since yo u like to tinker you rself ther e is another way o ut. I can b uild you a trick reed pipe kit w ith easy to follo w inst ru ctions for $45.47 . Low end Monarks l aw n tw o Monarks, bo th of wh ich I use fo r endure s. Co uld you please : give m e some tip s on how I could get m ore low end power? In mid -range and high -range I have plenty but in the lower range / need mOT~. Part of t he pr oblem seems t o be that the engi ne easily loads up when the RPM dr ops. R onald E: Lacy Livermore, Calif Be sure your timing is set at 3.0 m m. Also try a 276 needle jet and a 45 p ilo t jet wi th the needle clip in the middle notch. Fo r a main jet for yo ur area I'd start off with a 135. One other thing that m igh t be worth looking at wo uld be the mag crank seal, I've seen them leak and the engine would ru n but have zero ho rse power. I can help you out so me with a pipe. Only other way o ut is the reed valve trip, or a 150cc kit. Right in fron t I ha ve a sm all pro ble m with my CR I25 M Honda. It is suspensio n: A t th e beginn ing of m y ride, th e suspension isn't too bad, but as soo n as th e suspensio n war ms up, it bad side hops plus up and down. I hav e lost so me skin as a result. I don't really know w hat is wrong. Maybe it is because some of th e oil leaks out after it is warmed up or maybe it is j ust th e rid er. A t any rat e, I am going to . sugg est something. The total weight of bike and rider is 295 pounds so I t hough t I would get a set of. KONI shock s and put th e right weight of oil in along with a pair of light springs and set t he m up for the bike. N ow m y qu estion is what would I do