Cycle News - Archive Issues - 1970's

I How to make your 100-100 bike into ! agenuine enduro-type motorcycle 0') I"""'l By Larry Langley A few short years ago the future of the four-stroke dirt bikes looked pretty dim. Two-strokes reigned supreme and, horror of ho rrors, even Ho nda felt compelled to start producing them. As an out and o ut racer, the twostroke does boast a superio r power to weight ratio. However, for enduro competition to p h orsepo wer is not often necessary , in fact not desirable! What is desirable? A good enduro bike m ust handle well, b e able to maintain the speed ave rag es, be able to climb tall h ills in a single bound, a nd last, but not leas t , be reliable as a stone That's Jerry Co u nts, bounding h is little boonie-bounder o ve r some typical SoCaI ro cks t o chec k o ut the DID rims . Bet you d idn't think a 125 would pu ll a 4 .60 x 18 t ire. Accessory taillight ma kes it sorta lega l. God ble ss you Whisperin' Sm ith ! The ne w pipe di d the trick. Note also the move-up job o n the swi ngarm, w ith necessary gussetting . 8 ax. An d th at last is wh ere the fou r -st roke H o n d as shine. Their reli abilit y is legend. Bu t ar e th ey co m petitive? Well , three fo ur-stro ke Hondas made the t op 10 in AMA District 37 this year. Ho nda 's la test en try at firs t gla nce looks like a model chan ge of the old SL-125 but not so . It's a completely new motorcycle. An d it is so much sup erio r to the o ld SL, it's not even clo se. Jerry Co unts is a four-stroke freak. He 's also o ne of my endu ro rid ing partners. He rode a Triu m p h 500 fo r yea rs bu t w hcn H o nda started i n t r odu ci n g th ei r l ig h t we i g h t fo u r-str okes, hc co uldn 't resist b uy ing one, The Triu mph h as bee n in th e garage sin ce. He bough t an XL-I 75 firs t an d ro de in the local end u res wit h it fo r about a y ear. He b o ugh t th is XL-1 25 for his girl frie nd to ride b ut liked it so much h e has ended up ri ding it instead of th e 175 . So und strange? Well, in many ways the XL-125 is a better bike than th e 17 5. The transmission ratios are superior and the suspension is better, at leas t the forks. How much work docs it take to tum a st oc k XL -125 in to a de cent enduro bike ? Surprisingly not that much. Jerry kn ew what th e ro c k fields o f the Mojave Desert d o t o the stock so ft st eel rims, so he install ed a pa ir o f tough alloy DID rims. Since the stock tires were totally inadequat e for o ff-ro ad riding, Jerry rep lac ed the st o ck rubber with a Yokohama 3 :00 x 21 up front and a 4 :60 x 18 in the rear . The 4:60 sound s lik e a huge t ire for a lillie 125 t o pull , but actually it's a low profile tire and with th e pr oper gearing the bike will pull it well. Jerry would have preferred a 3 :50 x 21 but it just won 't fit between the fork tu bes. All the unnecessary stock eq uip ment was re moved. Th e tacho m e ter, battery and tum signals all we n t in to a box. Jcrry preferred to keep th e b ik e " so me what to st reet legal so he m ade a li ghtw eigh t h ead ligh t bracket and b ough t a n accesso ry tailligh r. He rewired the b ike so the ta il an d b ra ke ligh ts wo rked o ff ,of the ge ne ra to r inst ead o f the battery, It is no t tru ly street legal , but close. A Bultaco A/C hom was ad d ed that also wo rked off of genera to r c u rr en t. No w things were shaping up. He fabricated a n ea t fold ing shift lever to pre vent shaft damage {th a t 's an (SOT trick) . Th e stock 428 c hai n was replaced with .52 0 b y using an XL- 175 46-tooth rear sprocket and a CR 250 12 -too th co u n te rshaft. Everything bolts righ t up. Why go to the trouble? The vast majority of dirt bikes usc a 520 chai n and you. never know when you may have to borrow a part. to get home on. The stock X L-125 forks are pre t t y decen t. They are thc same as on the MT-1 25. J err y is always lo oking for a cheap way to impro ve things. Poring ove r Honda par ts h oo ks, he came up wit h the fact th at th e CR -1 25 d amper u n i t s w ould fit righ t in , giving th ree-quart er -in ch more tra vel and provide a lillie better d ampin g. Molly Blue ligh t for k oi l keep s th in gs up . The stock rear shocks we nt a way pretty fast, so Jerry had Charlie Cu rn u t t co nvert a pair off of his Tri umph for th e Honda. A t th e same time Jerry m odified th e swin garm by moving th e shock m ounts fo rward two in ch es. Combined with the 4. i in ch es o f tra vel in the shoc ks. J erry no w had a tad ove r six inch es of rea r wheel tra vel. J erry had to ra ise th e fear fen de r one inch fo r clearance b u t no other mod ification wa s n e c e ss a r y. \\l i t h th e s u sp ensio n modifica tio ns, the sca t h eigh t still re mai n ed th e same. The eng ine was left st o ck except fo r the exhaust. The stock ex hauster is a down pipe wh ich isn't the ho t set-up wh en bas hing over ro c k fields. J crry bu ilt a pipe which fed in to an Me\1 sp ar k-arrest er jsilencer . Whil c it tu c ked in real nice and kept th e noise down, powerwise it didn 't h elp . Th e bi ggest pr oblem was in o b ta in ing the proper one a nd thre e -eighth -in ch d iameter head er pipe , J crry ended up using o ne and one-half-in ch pipe, wh ich was too big. Fin ally Torque En gineering came out with a p ip e for the X L-125 and Jerry wa s do w n there for the first o ne off th e line. Now that pi pe m ad e a diffe rence, Better throttle resp o nsc and two or th ree ex tra ho rsep ow er were un capped . It m ay no t so un d like m uch bu t in a 125 th at's a lo t. The T o rq ue Engineeri ng pi p, t uc ks righ t in next to th e engi ne and exits o ut behind the frame by the shock. Nice. J crry ad de d so me handlebar s to fit him, b uilt some brackets to m ount his speedometer, watch a nd route chart holder a nd went e nd uro in g. The resul t ? First in class at the su per-t o ugh 125 -mil e National J ub ilee E nduro. Not to o shabby, huh ? At the recent tw o-day Last Ch a nce End ur o J erry came in fourth in class . He got lo st a nd gave up man y po in ts b efore he finally go t back onto t he course, o th er wise he had a good chance to win his class there also . The XL -125 fin ished with a b ro ken rear hub (o ne o f the spo kes pulled o u t) . He 's lacing up th e rea r wh eel with the spokes laced in a cross-three pattern in st ead of the stock c ro ss-two. Again playing detective Jerry dis covered th at Honda XL -250 front spokes were a perfect fit and ch ea per than c ust o m spokes. Stronger t oo. The bike has ample ground clearance, but a s kid plate was built anyway. No w J erry h as himself a good little enduro bike wh ich is di fferent than m o st b ikcs compe t ing in Dis trict 37 en d ures. It 's no t su per fast b ut it is a terro r o n up hill s - t he worse th e b etter. J erry d eligh ts in blowing off th e ring-dings pi ckin g hi s way up th e n asty de sert h ills. J erry even too k it u p no rth for a n end uro and fini sh e' but found t ha t a co u, -Ir. of r \ d.ugc::. . .. Id h e necessary to be competitive ir, the lTIU U . J erry is n ever satis fied, so the ne x t th ing on his list to install is a full flo atin g rear brake and a constan t velocity carb off of a CB 350. •

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