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/128084
4th Annual / XT valves an d th us allow for bet ter irf low a t a given rp m. Acco rding to saa cs, ou r p ist on need ed to be clea rneed abo u t one- hu nd red- thous and ths n t he ex h a us t si de a nd s ixty-thouandths on the in take side. Isaa cs got tr icky with our re bu ild in he conversio n of our mot or to a rid eide shift. It wasn' t really necessary - the nly reason for it bein g that we would ave a few s h ift levers durin g the nev itab le odd lay d ow n - b ut it was rett y cool. Isaacs charges an extra $150 or the conversion, and he doesn't recmmend it be handled by anyone withJUt the proper equ ipme nt and train ing. That was about it as far as the eng ine ebu ild goes . Isaacs rebuilt the engine arefully, checking and double-checking II of th e tolerances, degreeing in the m and ad justing the valves. The only xher thing that Isaacs did was place an luminum plu g in the tach drive hole on op of th e h ead . Do-it-yourselfers or ow(er) bu d get racers can find a lot of uice by cha ngi ng the cam and rockers n a sto ck 500cc engine. As I stated very lea rly last week, I have perso nally been axed by su ch motorcycles already . "The 500s lack a little bit of torqu e nd acceleration, but all in all, they are ery close," Isaacs says, a d d ing once ga in that any Yama ha IT or XT single akes fo r a darn compe tent powerlant, be it for sports man or vin tage raeng. "If you go out and buy a Rotax motor nd the n spend a couple gra nd to make t com p etit iv e, you ar e talking ab ou t 5000 jus t in the powerpla nt. I haven't seen an ATK to date that could corne off he showroom and ma ke National-type owe r. That's what you would be ru nin g against a t th e local level. And in he vintage classes, h ell, you 're righ t here already ." All told , ou r "a ll - new" v in tag e / portsman Yamaha engi ne tallied up at .gh t around $1200 wit h all of the new nd shi ny bit s and pie ces, and the labo r. or Isaacs, running one of these old amahas makes pretty sou nd financial nse, especially wh en their reliabili ty is rou gh t into the equation. 'T d hat e for peop le to think that I am tal k in g d own on the Britis h s tuff, because tha t' s the majority of my busine ss , b ut I co ns ide r t h is [Yam ah a ] engine to be like an upda ted BSA Gold Star," Isaacs says . "O nly, if you ' re going to build a real Gold Star, you had bette r allow three times the amoun t of time to do the work. I bu ilt my BSA 500 to be as fas t as a Yama ha - an d faster than the majority of them - bu t my maintenance w as lik e, 125 h ours per ra ce season. I built a Yamaha for a guy that I sp ons or, and if w e had m ore th an 10 h ours of m aint en an ce in it , I wou ld b e s u r prised ." O ther than specify ing that we kee p an ey e on the va lves a nd th e ignition timin g, an d reli gi ously cha n ge th e oil about eve ry three to fou r race s, Isa acs tu rned u s loose, sta ting that w e cou ld expect ou r re vamped sing le to en joy a lon g and healthy life even under the rigors of hamfist ed local sp o rts ma n a nd vintage competiti on . A typ ical season on big tr ack s woul d mea n tha t w e mi ght want to tear down the top-end every 10 races to tak e a look. On short tracks like ou rs in So Cal, Isaacs predicted tha t we wo uldn't need to d o anyt hing that serious for a season and a ha lf or lo nge r . That was g009- news. The bad news was tha t w hile a ll of this work wa s movin g along, so wa s the ti m e , a n d ou r p ro ject s ta rted to la g behind a little bit. Okay , actually it was a lot. Stick with us, though. We're goin g to press forwar d next week and ge t this eN baby read y to rock! US TOYOTA Official Truck of G len Helen presents ~ .~~ Last Race o f EilDri PRO/AM the Cen t u r y CHAMPIONSHIP AMf1IJCAJI1IIfTrfIIIt:'fC ASSIJCIA1I01I W arm up for t he 2000 A MA SXi':'9!~~~ ~ If~ ....... ~ iil,l,l,l,i;,jll;ii,l P ro Purse to exceed '$ 2 0 . 0 0 0 Pro R ace o n S unday , D e c ember 18th, 1 8 8 8 by Invitation O n ly ! . - - - - - - ---.... In v it e e s in c lu d e McGrat h , F erry, & m ore Round #2 Southwest Amateur Championships T h e A mateur race cons ists o f t hre e d iffe r e n t types of motorcycle r a c ing : S tad iumcross , Grand Prix & Motocross ••• ~1IIiiiiIlIIIl There wi ll be a n AMA Amateur Champio n in each class a nd indiv id u al w inners for each day. Supercross Track - A ll Amateur c lasse s (Saturday, December 18) Motocross on Nat io nal T rack - All Amat e u r cl a s s e s $5 00 ___) Practice starts at 1 2 pm 24 Hour Information line 909-880-3090 www.glenhelen.com per b ike-Open p r actice Thu rsday per person per da for Sunday f or both days for child ren 5 & u nder for 6 - 12 y rs Gates Open Thrusday, Cec. 16 Open practice 8 am Gat e c lo s e at 1 0 p m ( Sunday, December 19 ) Pro Event $7,000 Gates Fee $ 1000 $ 1500 $ 1500 F REE Gran d Prix (45 Minutesl & the 1 25 / 2 5 0 P ro S h o o t Out - 8 am- 250/ o p e n / 4St ro k e s all skil l levels - S am - 80c c/60c c lWo m e n a ll s k ill leve l - 1 0 am - all 1 2 5cc - 1 1 a m- S en io r slVe t s / .Jr . Vets a ll s kill levels over S p ecial AMA Amateur Championship T r o p hy in each class $ 1000 c Plus, prizes totaling Friday, Cec. 17 6 am - 10 p m Saturday, Cec. 1 B 6 am Sunday, Cec. 1 S 6 am " Gate closes 1l? plT1 each night ( Racer's Entry Fees $60 00 $80 00 $35 0 0 $15 00 ) Pre -Entry-three days Post Entries-three days per class . p e r day for p e e wee each day UVdij ij,;/ ~ CSE, elL":. ~PE S PEP C • M::::¥i.oo"'\l ~.> ~BC 1a 948wonderfu lly noof MAN '48 Is l e ISLE s talgic r e co r d of the TT • short but of Man TT, (# 1097) 1948 sow a record number of e ntrie s as Norton , Velocette and Mo ta G uzzis dominated . Sta rs of the post-War e ra - Fredd ie Frith , Bob Foster, Artie Be ll, Omobona Te nn i and other fam ilia r faces we re d rown once more to th is legenda ry ro a d ra cing festival. Pro ba b ly the first n film p roduced after the seco nd World Wa r, this re cently disco ve re d film wo n an a ward for its enthusiastic producer Sam Co les . There is no sound other tha n the info rm e d co m me nta ry of Graham Wol ker, b ut th is in no wa y detracts from the atmosphere and excitement of another chapte r in Isle of Man roa d racing history. Features a ll the p re -r ace activities involved right up to the wo rm up and the G rand Parade, as the bikes and riders are ma rched to the starting g rid flanked by the Boy Scouts. - en en en 36 m inutes from White Star / Duke Video. To Order Videos, Use the Video Order Blank Elsewhere in this Issue of Cycle News This release $34.95, Order Videos On-Line at WWW..cycieneW.s.colT1/product/videos.htmlinciudes shipping. 17