Cycle News - Archive Issues - 1970's

00 ASK • • n T 29 .0mm 92 .0mm 42 .0mm 41.0mm T R A NS -?j26.0mm r Waffle iron l a w n a 19 74 R ich m an 250 I'R m o to cross er. The engine has st raight ty pc f inning o n th e cy linde r and head, wh at I would lik e t o h no w, is there any f dif f erences be tween the uiaf le-fin ned engin e and the k in d I have. I read your article on th e R ich ma n I' R in a Cy cle N ews issue. It was ver y helpf ul fo r I also had wo od ruf f hey prob lems. I basically use m y R ich man I'R fo r fas t cow trailing an d fun riding. I w ou ld ap p reciate any he lp on mak ing it rUn st ro nger. w itho ut the reed value set up or w ithout th e radi cal 3 0 ho rsepower port ing. Hot set-up for 125 Pento ns l a wn a 19 74 125 cc Pent on. M y ex p erience w ith K TMs im p orte d t o the U.S.A. has been t hat th ey are un der carbu re te d. My m achine is fitt ed with a 27.5m m Bing m odel 5.3. I w ould like to know th e modificat ion and adjustm ents t o th e carb that w ou ld b ring it to Bing mo d el V84 spe cific ation, prefe rably 3 0m m . Or sh ould I simply start w ith a n ew m o d el 1'84 and enlarge the m anifold. I do not have C.S. p orting mo d s on t h e e n gi ne bu t w ould app reciate detail drawing s to modify an d clean up my ports. Please bear in mind that I wish to adapt th e 3 0 m m V8 4 Bing. I run e n d u r o a n d occasio nally m otocross an d am in t ereste d forem ost in reliability. Remove and make port r ound for TT & sho rt track ON LY . CJ - R ichard Figu ra Ransomville, N. Y. 28. 0mm Ted Sm ith A sh eville, N.C. 42 The Sachs engine, wh en it's built right, takes no back seat to an y bike o n the market; an d for you riders that still prefer the Sa chs engine they have a new one that will be out sh ortly, even stronger than th e G.S. Let 's take your problem an d start with th e car bo The Bing Model 53 ca rb is a little bit sm all , (slide wise) t o bore to a full 30mm bore . The biggest you can go is 28. 5 an d still ge t it to perform right . The 30 m m V8 4 carb will be th e be st ca rb for y o u to use but will set yo u back a touch o ver $6 0 and ano the r $5 for necessary j e ts. With th e V84 carb you need to have as sp are jets a 2 76 an d a 27 3 needle jet, pilot jets 25 , 3 0 , and 35, main j ets from 130 to 165. These jets will le t yo u tu ne your bike for any track th at y ou may ever want to race o n. If yo u're sh o rt o n bucks you can modify your stock carb and it will handle your ne eds very well but not quite as well as the V8 5. First, even though you can bore the s t oc k c a r b t o 28 .5 m m I don 't recommend it because o f dependability an d tuning prob lems th at you may run into. Stay with 28mm for the bore size. A lathe will be necessary to bore th e carburetor. Th e fir st st ep is to ch uck a piece of one and three-eigh th in ch bar stock in a three-jaw ch uc k. Next mach in e an area app ro xim at ely one inch lon g to a dia meter over which the carb will just slip on. Now before th e boring is done the jet block an d the atomizer tube m ust b e removed. (See drawing.) Mount the carb o n the fixture that we just made and tigh ten the ca rb clamp to hold it in place for the machining. Use a dia l indicator and be certain th at the ori ginal bore o f the car b is running true. With the carb properly set up, proceed with the boring. When boring is finished , remove all sharp edges and thoroughly cle an the ca rbureto r before you put it back on the bike. Now let's massage th e cylinder and head a little for so me m ore p onies. Modification s sh o uld be mad e o n ly to engines in top c on di t ion . The cy lin der and piston sh ould be miked an d if th e cle ar an ce is o ver .0 05 th en th e cylin de r should be bo red to th e ne xt over size after you get through porting it . When y ou rebore a cylinder, set it up with .001 5, run it in easy for about on e hour , th en pull it down an d chec k fo r high spo ts: This is the best way . If you don't have tim e to break it in this way , then make it .002 to .00 25 and give it a short break-in before racing. If y o u 're plumb out of time an d going straigh t out to th e track from the sh op wit h no break-in, better go for .003 or you might wind up with a one-piece engine. 111e diagrams show the stock ' cylinder Fun an d Fast makes skid plates for the Hondas and you can have your local Honda dealer order one for y o u. ~IT gears are the gears out o f the end u ro bike an d I think th at it is a wide ratio gear set. For wh at it w ould co s t yo u to replace th e gearho x I d on 't think it wo uld be worth the expense. (E d. n ote - It's not. Yo u have t o replace t he m ain shaft as w ell as th e gears.} I'.S. Cycl e New s sti ckies on th eir way. length an d port dimen sions when work is co m plet ed. Do not le ave square co rn ered ports: a m inimum radius of o n e -fourth sh o uld be left. Bevel ho rizontal edges o f po rts where th ey open in t o th e cylin der. This will prevent the rings fr om h o o kin g the edge o f the po rts an d breaking. After port ing is co mple t ed mi ll the he ad 1.5mm (.06 0) for rac e trac ks under 3 0 00 fe et alt it ude. For race tr acks of 3 0 0 0 feet o r hi gher, mill th e head 2.0m m (.0 80 ). With G.S . he ads d on 't mill th em. They're on th e sh aky side as th ey are. With all the po rt in g done and the he ad remachined, asse m b le the engine an d torque th e head down us ing 2 1 to 22 ft. /lbs . With the en gine back together chec k the timing an d reset it to 3. 0 to 3.3 m m BTDC for MX o r en d uro. For TT or sho rt t rack set 2. 5 to 2.9mm BTDC . For spark plugs I recommend Bosch . For trail riding a W240Tl to W260Tl will work th e be st. For the averag e race track wh ere a co ld plug is needed, use a W280M I plug. If y ou 're go ing to be flat out f or long periods of time use W290TI6 or W310Tl6 racing plugs. These co st $4. 85 each but are well worth it . Th ey 're chea per th an $3 0 for a pi ston. If y o u 're going to be real serio us you migh t think about replacing th e rod with a ro d assem bly out of a 175 KTM Penton. Broken rods make a big , big mess out of things wh en they co me apart at 10,000 RPM. No te: If you use a 17 5 Penton rod assembly be sure th at yo u us e yo ur c ran kp in be cau se it's a tap ered p in while the Penton isn 't. J etting y our ca rb if y ou bor ed it o ut to th e 28 m m size, I'd sta rt with a 27 6 needle j et, a 45 p ilo t an d a 150 main j et. ' If you rep lace d it with th e V84 Bing 30 m m sta rt o ff wit h a 27 6 n eedle j et, 35 pilot and 15 5 main je t. With ei ther carb , whe n yo u sta rt tuning se t th e needle cl ip in the middle not ch and the air sc rew o ne-q uarte r to o ne-half tum o u t till y o u get it close th en . flne lin e it with these last two adj ust men ts. As far as com plete ca rb s o r p arts I guess I'm th e only on e tha t car ries a full in ventory o f Bing carb s an d parts. y o u make a cus tom on e ? If t he airb ox is in th e w ay ["II try an d m o dify it so th e pipe w ill f it. fl o w much? How will it affect the p otoerband, h orsep o w er and will it get in th e way while rid ing ? lvIihe Conl o n Buellto n , Calif. Forever live a sq uare barrel Maic o . Yes, I can ma ke yo u a high p ipe o r a pi pe kit wh ich y o u co uld put toge ther y o ursel f an d save some m oney. Also th e Flyi ng l\lachine Factory in Harb or City , Califo rn ia co uld build y o u a p ipe , and they' re close r to you . Jus t te ll Donny that y o u w ant torque, not a racer. Will it get in th e way of y o ur leg? No, no t if yo u're bow legged on the right side . Cost o f pipe , I can 't speak fo r the Flyi ng Machin e Fact ory but from me th e p ip e w ould run you $ 59.95 co m ple te o r in ki t form 541;9 7. Elsi rides the range Will a 36m m Bing o n a st ock cy lin de r of a 25 0 Honda Elsinore increase th e h orsep o w er an y , or is a mild porting job needed ? 1 am no w using a D&C p ip e and head gask et. Wha t w ould happen if I had th e head m illed [thick n ess of D&G he ad gask et). 36 mm Bing, D&C p ipe ? Wo uld I ne ed a p o rting j ob to get th e f ull ben efits of the Bing ? . Wh ere can we p u rchase a sk id plate fo r our 25 0 Elsino re ? A Iso w here can we ge t th e 3 6 m m Bing f ro m an d some jets ? Ou r nea res t m otorcycle d ealer of an y so rt is 350 m iles away , so getting parts is no t lik e g oing to the co rne r 7-11 st ore, What are .\I T gears an yh o w ? P. S . If you hav e any Cycle N ews st ic ke rs p lease send some. J im K Pt. A rth u r, Tex as Fo r a fac t, the 36 mm Bing will give yo u increased ho rsep ow er . Th e only p lace I kno w th at you ca n ge t o nc to fit y o ur stoc k Ho nd a in ta ke is fro m m e . be ca use the carb h as to be m ach in ed to fit. B e tt e r ch ec k yo u r com p res sio n I've chec ked th ese tw o en gin es o ut ver y closely and th ere is no difference in them th at I can find. Now I don't kn ow abo ut th e new V- 75 becau se "l have n 't seen the inside o f on e, ye t. The ree d didn't make the engin e radi cal, in fact it mad e it easier to ride th an it was sto ck. Lo ok closel y a t the dyno char t and yo u ca n se e that it had more torque and more h orsep ower every wh ere . Also the p ower curve was flatter. 111e only other thing th at I co uld do fo r y ou if you do n' t wan t to go to a reed en gine would be to b uild yo u a pipe. Yam my whammy I have a Yamaha 3 6 0 MX an d would lik e to kn o tu a f ew th ings (1) h ow f or up s hou ld I m o ve th e sh ocks withou t chang ing th e top m o u n ting ? (2) Th e sh oc ks I have n o w don 't have mu ch travel. I w ou ld lik e to ge t lon ger o nes, ho w lo ng sho uld 1 get th em ? (3) I w e igh about 22 0 pounds, what w eight of spring sho uld I get fo r a m oderat el y firm rid e ? (4) Th e forks aren't stiff enou gh. Sho uld I get heavier oil, o r st iff er spr ings ? (5) Th e bik e sm o k es a lot. Sh ould 1 get n ew je ts ? If so w hat num ber of je t sh o uld 1 get? Are th ere any inexpens ive engine m odifi cat ions ? J im Crit ck Pleasanton , Calif (I) When you move the bottom of the shock yo u must retain a half-inch tr ail o r you will bend the stem s of the sh o cks. (2) You could use a Curn utt shock, wh ich can be made with as much travel as yo u want an d as lo ng as yo u need so that they won't let th e tire bottom out in the fender or frame . (3) If y o u us e Curnutt s hoc ks , he will re commend the sp ring weigh t that fits you. Give Curnutt a call and ex plain yo ur prob lem to him . He's good p eople an d will help you out . Ph o ne (714) 36 7-9 179. (4) Stiffer sp rings would be the right way to go , or make a one inch space r fo r ea ch tube and put it on top o f th e sp rings you have now. Refill y our forks with Moll y Blue Heavy. (5 ) So unds like yo u are on th e ric h side, alrigh t. Rem o ve your main jet, it 's in the mi ddle o f y our ca r b and right at th e bo tto m . Lo ok at th e number on the side 0 f it an d go down o ne step fro m wh at is sta m ped o n th at j et at firs t. T he n tak e a plu g rea din g after a full -throttle run. You wan t the plug to be a nic e , light brown co lo r. (6 ) Sorry , horsep o wer costs money, but th e Yam aha cylin ders are no t the before y o u mill yo ur head o r y o u mi ght ge t the pings. Abo ut 160 pounds is all Square forever I have a '72 .Haico 250 square barrel an d I need an up p ipe (I wa nt to go cow trailing ). Do you mak e the m? Co uld sm oothest finish o n the market, so y o u need . Go easy o n th e p o rt ing, j us t a nic e some. Whi le y o u' re in the re , lower clea n up will pro babl y be en o ugh fo r yo u . Mayb e inst all o ne o f th e new Fo rget rue pisto ns. polishi ng up all th e ports will help the intak e .040 b ut d on 't raise the ex ha ust p ort. It 's 'almost to o mu ch now and with ' yo ur we ight you mi gh t be in trou ble (n o t orque ).

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