Cycle News - Archive Issues - 1960's

QUESTIONS AND ANSWERS By The * Answer Man Send your questions to The Answer Man, Care of Cycle News, BII 498, Long Beach, Calif. Sorry I vollne of mail does not allow us to send individua I repl ies. QUESTION: 1have a 1955 650cc T riumph. My problem i s k eepin g it runnin g. 1 have to fl ood (ti ckl e) the carbure tor to get it started, but it promptl y dies. If 1 keep th e tickl er depressed it will continue running, with gas pouring out al l over the engi ne. 1 hav e campi etely di sassembl ed the csrb, i ncl udi ng the je t bl ock, cleaned it and blo wn out all passages and jets. I' ve cleaned everythi ng from th e gas cap on down. Th e carbur etor flange was slightl y bowed, so 1 fil ed it level . 1 can't thi nk of any thi ng else to do! K.H Kodi ak, Alaska. ANSWER: P ro v i di ng noth i n g e l se i s wron g with the engi n e mecha nically, such as imp rop er ca m t iming or ignition timing, the fa ult must lie in the carb float chamber . Somet hin g such as a bent fioat spindl e bush or wron g si ze bush, i s pr eventin g the float from fallin g by i ts own weight si nce you have to f orce (tickle) it, t o make th e fu el fi ow . I t' s very hard to tell what' s goi ng on i nside a fl oat chamber unless you buy an in exp en si ve, y et pri cel ess gadget known a s a "Gas Gazer ," produced by "Pabatco." Th i s tran sparen t pl as tic window l et s y ou see j ust what 's t aking place i n the ca rburetor floa t channe r• QUESTION: 1 have an early model • pre-unit 650 Triumph that has a small main bearing on the engine's timing side. 1 am tearing it down to overhaul completely including changing the inserts and installing new bearings. 1 hav e heated the cases to cherry red and still cannot get the bl ankbl ank small bearing to come loose [rom the case. What shall 1 do? S. P. -Bakersfi el d, Calif. ANSWER: You pr obably did not kn ow that the small bearin g i s held by a re t ai ner ci rc l ip, It sounds a s thou gh you als o haven ' t bro ken the crank loos e f rom th e beari ng i nner rac e. The crank and beari ng must hav e sei ze d due to a s lightly ove rsize 'crank , Y ou may hav e to br eak. it l oose with a hydraulic pr ess . B e very that the case i s s upporte d ca re f ul e venl y or y ou may br eak it rather than just fr ee the bearin g. I su ggest yo u l eave out the ci rc lip next ti me and turn th e cranks haft down with emery cl o th , so tha t a bearin g will not fre eze again. That circl i p i s not nec essary. QUESTION: 1 hav e modified the i ntake port on my twos troke and it feels as though 1 have changed the power output somewhat for the better. 1 can' t affo rd a flow bench test j ob and don't know how 1 can chec k, myself, if the int ake has been properly shaped and poli shed. Any hel p you can give me on how to check thi s out , would be greatly apprecia ted. V.R.-Duarte, Cal if. ANSWER: I mmedi ately after doin g th e por t j ob , the e ngi ne s houl d be run f or abou t 30 minutes and th en the top end torn down for inspecti on . Carbo n deposi ts on the pi s ton cr own sho uld definitely sho w the flow pattern that took plac e while the engi ne was running. T h e pattern s hou ld be ev en on both sides and cente r , from the port si de to cyli nder wall . A l so chec k the deposits on the head and cy linde r walls. QUESTIOt~: 1 have seen racing pis - tons in the automotlve fi eld and a few motorcycle manufacturer s, that have groo ves machi ned all around the piston skirts. What purpose do they acco mplish? D.C .Hermosa Beach. ANSWER: Those groove s accomplish t hree things. First, a nomi nal amount of wei ght i s remo ved that resul ts i n a lighter pi s t on; sec ond, thos e groo ves carry oil an d gi ve the cy li nde r wall s superior lubricati on. Third and l as t , they redu ce th e amount of pi ston and cylinder wall co ntac t , thus slightly reducin g cylinder heat. QUESTION: 1 am interest ed in desi gn of two-stroke expansion chambers. Can yo u recommend any ref erence work in thi s fi el d? Or do you know if soni c velocities at different temperatu res and pressures have been pUblished? I would appreciate any in formati on you can give me i n thi s area . R. W.-B erkeley, Cal. ANSWER: There are several publi catio ns tha t hav e been devoted to the two-stro ke exha ust sy stems , but though tech nical , they are written in an at t emp t at simp lifie d form f or t he layme n. I do not know i f this .is the l evel of information yo u seek . If so , thes e are the wor ks 1 re comm end. Gordon J enn in gs ' " T uned .E xha us t ,F or Th e T wo-Strok e s ,· publis he d in a tec hnical manual by Cyc l e World . " T wo Stroke Exha ust Sy stem" by Ray Baco n, A.M .1. Mech ani ca l E ngineer . Thi s book i s av ailabl e th ro ugh rld and .F Ioyd Clyme r P ubCycle Wo licati ons. A good place of ref erence for Soni c Velocitie s , i s in books on Acous tical E ngineeri ng , QUESTION: 1 wish stretch my frame by heating and thus increase the front end rake. What 1 would like to know is, where will the greatest points of stress be in the front end, after I have done this? D. K. - Boston, Mass. to AN SWER: If yo u do not know how t o pr operly apply heat t o metal i n th i s bend in g process , the grea tes t point of s tress wi ll be ri ght there! B ut , a sid e from that - th e greate st point of str es s will be where the f rame tubes j oi n the frames s tee ri ng head. I hear tily sugge st yo u add necessary gussets at that poi nt. QUESTION: Whyisit that an exhaust valve is not - as big or even bigger than the intake valve in most engi nes? It seems to me that since the gasses have expanded when exploded, there is more to remove from the cylinder than went i n. R. B. - L aguna Beach, Calif. ANSWER: Th e reason fo r a prop ortionately smaller valve on the exhaus t si d e i s due t o th e fa ct or y ou menti oned. Expanding gasse s . T he expans i on in it self helps t o prop el the air fro m th e cy linder , coupled with the upward mov ement of the exha ust pis t on s tro k e. On the intake, th e only basi c aid i s pi st on tr av el itself , although at valve overlap t her e i s a scave nger effe c t which adds th einc omin g charge on ly slightl y except i n competiti on engi nes . QUESTION: lawn a 500cc BSA. I t i s street l egal and the only engi ne modification i s swi tch ing from one carb to two. 1 would like to know; A -Can I pull the baffl es out and still run i n street cl ass? B-What class will i run i n? C- How much it cos ts, entrance fee, pit pass and competition fee. K.W.Chula Vista, Calif. ANSWER: With that en gi ne modi fi cat i on yo u woul d s ti ll be i n stoc k stre et cl ass at our l ocal So. Cal. dra g st rips and : .A- Yes , y ou can . B-Cla ss would be C stock street . C-.At Li ons Drag Strip , the entry fee is $1.50 on Sunday , Satu rday s , I r wi ndale Raceway cha rges $2 .00 entrance fee . B ot h of thes e l ocati ons ar e th e same in pit pass and e ntry fees . One d ollar for entry and one for pit pass. thro ugh my SOcc Suzuki and prepared i t for small bore sportsman road racin g. However, after rebori ng to 100cc' s I must now change the por t timi ng. Can you tell me where 1 might get hol d of the specifi cations for successf ul changi ng of th e port timi ng on my Suzuki or what th e specs are ? U.S. - L ong B each. .JACK 0 1str! buted by: AMER ICAN COMPETITION !:NGIN EERI NG J 63 S Fairfax Ave.Los Angeles Cal if. 90036 . , ~ r.J YAMAHA ..:l Don & Ray's Mot orc yc l e Shop 1223 W. A ve. I , L ancast er , Cal if. U U ;:,.., (805) 942-9624 BULTACO & GREEVES Fiberglass Tanks $40. w/cap PLUS a co..,l8Ie line 01 FIRllass part. lor 8ultaco Mall Order 10: VEGAS CYCLE CENTER 1020 Fremont, Las Vegas,.Nev. 89101 IAWASAII Headquarters T he Suz uki Mot or Co. , Ltd •• prepares a se rvi ce new s b ulleti n that is available to deal ers and custom ers. This bulletin co ntains spec i fica t i ons for modifying their vari ous moto rs to compe ti ti on s pecs . A sk y our l ocal Suzuki deal er to obt ai n the ser vice bulletin that pertains to your prob l em or send a requ est to U.S. Suzuki Motor C orp . , se rvic e Departm ent , 13767 .F re e way Drive , Santa F e Springs . Calif. 9067 0 . ,. SIMPSON MOTORS -,. QUESTION: 1 have been told • ,. 4210 San Fernan do Rd. Glen dale , Ca li l. 91204 • ,. that someone makes an alloy cylinder for 650 Triumphs. I s thi s tru e and if so where can I get one. Q.B.Fresno, Calif. . AN SW ER: The onl y alloy cy linde r made i s the big di sp la c ement kits by Webcor and hand l ed by W ebco of Californi a. T hes e are fo r 9 stud unit co nstruction eng i nes . Once a l ong ti me ago Wellw orthy made a lloy bar rels for p re- uni t engi nes , but tha t was di scontinued! QU ESTION: I have purcha sed a val ve BEACH CITIES CYCLES 525 N. EI Camino Real San Clemente, Calilornia 014> 492-&141 .................. .. F i Um n .\ i r F iJl l' rs , .l uds nn Prods. .. F ra nd s('o Ca s to roi }, Dri- st td e , F i,. ~ lils .s tanks Ii; s(·a ts• .John Co np e r Ii; ,. I II ~ .l nhn Bno ts. Al l Availab le Fro m ,. ntontesa JACK ENDE RSEN OF BURIEN MONTESA, Buri en, Washi ngton has been a Montesa dealer lor one year. The reason he sells Montesa i s that it i s ·very strong and th ere i s no other machine like i t . I t i s the best dirt bike money can buy" , ANS ER: Nop e, W JACK EtmERSEN BURIEN MONTESA 145 Southwest 152 Seatt le , Washington 98166 ~\V4 M ONTESA M OTO RS . IN C . Sole U .S . Dis/rib uto r ANSWER: It sure is too late! I s ugges t yo u get a gui de that is ov er size by .002 i nch es. T h es e ai e available from y our Triumph deale r . 3657 Beve rly Bou levard Los Ang e les.. Califo rn ia 90004 · U· SHAPED ADDITION TO · C· CLAMP Ju st wel d a bU' s ha ped pi ece of metal t o the clamp that will fit you r va l ve co llar . QUESTION: l awn a 305 Ya maha tha t is havi ng d utch probl ems. T he unit is very noi sy and grabs. Shoul d 1 replace the whol e .unit as my deal er recommends or do yo u think 1 can ge t by wi th some pa rticul ar part repl acement ? V.K.-San Di ego, Calif. 'Montesa - Hodaka - K awasaki WESTMINSTER SPORT CYCLE Motorcyc les ANSWER: G R Loui s uy . l (114) 893-1051 l 7574 Westm inster Ave. Westminster, Cal. ~ .. ' It,. .. (213\ 247-3068 ,. .*.* •••.6 ••• * •• **.** spri ng compres sor desi gned for smal l sports car engin es but on removal of my valve springs, ezc., I find it very difficult to handl e. Sometimes it slips off and leaves sc ratches or scars on the valves and collars tha t coul d be very dama-ging. I sn't there a bet ter tool made and where could 1 buy one? B.B.-Buen a P ark. shor t of a hydraul i c press th ere are no spri ng c ompre ssors mad e es peci ally suited to moto rcy c l e heads. B ut, y ou can mak e a very effi cie nt one for a ve ry mi nim al cos t . ,A carpen ter 's "C· c lamp i s i deal with only a sligh t modificati on needed. One end of the c lamp has a sea t or cup whi ch wor k s we ll on t he valve' s head so there i s onl y need of a c ha nge at the end that fits the valve colla r . (See be l ow .) V) El:: r.J ItI LM~CASTER IT'S ANSWER: guides in my Triumph alloy head, but one of themI can pu sh into pl ace by hand. Th at's too lo ose isn' t it? D.B.-Sant a Ana, Calif. t tce . RIM QUESTION: 1 hav e recentl y gone QUESTION: 1 am in stalling new valve That's a probl em that has co me up before with 305 Yamaha s . I th ink replac ement of the c l utc h throwout bea ring sho uld s uf- A.C.E.

• Cover