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/126980
to the YZ were co mpletely designed by Baker, su ch as the rear disc brake. T he dua l-a ctivated pi sto n rear disc an d hub is built from scratch using 20/ 24 alu m in u m a lloy. The com p lete rear d isc brake system is sligh tly ligh ter than th e stoc k drum brake. In the sus pension department, · Bak er reva lves both the rea r shock a nd fro nt fork for less. co m p ress io n, a nd he rel ies on th e standard sp rings. H e uses Kal- Gard 5w t. oi l in th e shock a nd in th e fork, measured six in ch es below th e fo rk tube. Ba ker trash ed th e stock five-speed tran sm ission a nd replaced it with a 1983 Yamaha IT250 six-speed transm ission. Some m odifications were needed but n othing extre me ly m ajor. H e had to add a 3.5m m spacer on th e dead end bearing o n th e im p ut shaft, a nd drill o u t th e imput shaft by 15mm for th e cl u tch push rod. T he new transmission required fin al drive gea ring to be cha nged, as wel l. The stoc k YZ co mes w ith a 14tooth co u n tershaft sp rocket and a 51tooth rear sprocke t. Bak er rep laced th at w ith a 14/ 49 co m b in a tion . Baker des ig ned th e rear sprocke t out o f th e ex tre mely ligh t but strong 20/ an Answer Products sp ark arrester/ si lencer attached. A h ea vy-d ut y al u min u m sk id plate, built by DBP , wa s installed on the Yamaha. Bak er said his skid p late mounts sturdier and is li ghter than most aftermarket skid p lat es. Although th e YZ we rode didn 't : h ave a lighting system inst alled, Baker has m ounted th em o n o ther YZS , u sing a Yamaha T ri-Z ATV ignition an d half th e cran k, which also g ives the YZ a heavier flywheel effect. Baker u sed p roduc ts from a few other a ft ermarket co m pa n ies to finish o ff th e Ya maha. H e installed a la rg er , 3.5 ga llon, sano-lookin g IMS (Interna tio nal Motorsports) gas tan k tha t bolts ri ght on a nd uses the stock YZ radiat or shrou ds. Baker u ses a lower profi le YZI25 seat padding an d b lu e co ver, both built by Ceet Racin g Pro du cts. T he Ceet p adding, says Bak er, is more durable th an stoc k p adding. T h e front n umber p lat e/head ligh t assemb ly a nd h an d guards ar e made by Acer bis P la sti cs; th e tailligh t is a bolt-on Flanders Int ern a tional accessory. Bak er in stall ed blue H onda C R for k boo ts o n th e Yamah a, an d he replaced th e stoc k Yamaha handlebars for Intera m H on da C R-be n d h andl ebars, w hich have less kickback than the stock u n its. Dallas Baker swapped the stock five-speed t ransm ission f or a 1 9 83 Yamaha IT250 six -speed tranny. (Right ) Pipe is made by Pro Circuit . Hop up: Dallas Baker Products' Yamaha YZ250 Enduro It's more'than just trick By Kit Palmer Finding a production 250cc, two-stroke en duro bike these days is getting a little on the tough side. There just isn't a whole lot out there to chose from, especially if you wa n t to go J apanese. There are a few E u ropea n rno d e Is o u t th ere but .J a pa n ese-wise _ " ' , zi lch l T here is a n a lte rnative, however. You can take a productio n J a panesemade 250cc, two-stroke motocrosser a nd tra nsform it into an enduro machi ne, w h ic h is exact ly w ha t Dallas Bak er of Dallas Bak er Pro - d uc ts (DBP) d id to a 1987 Yamaha · YZ250. . D II B k ' . I d . a as a .er ~ co~pa ny IS oca te 10 Orange; California, a nd he specia lizes in b uild ing and des igning performance engine, fra me and suspension parts for just about any make motorcycle . One of Baker's latest crea tions is hi s Yamaha YZ250turned enduro. Some of the modifications made Baker des igned a sano, dual-piston rea r disc brake for the YZ . Braking power was strong and we had no problems w ith fad ing . After Bake r's motor modifications, the Yamaha produces tons of lowend torque, wh ile maintaining plenty of power on top. 30 24 alu m in u m alloy. The co u ntershaft a nd rear sprocket were bu ilt by C ircle Industries for Bak er. Baker swap ped the stoc k dri ve ch a in for a stronger RK O-ring chain. Baker a lso repl a ced th e stock Mikuni ca rb ure tor with a Keihiri, which ca me pre-jetted fro m Sudco Interna tio n al. The Keih in, acco rding to Baker , is more responsive and eas ier to jet , a n d isn't quit e as affect ed by a ltitu de a s th e Mikun i. Baker also port ed th e Yamaha to give it m ore p unch a t low - to midrange. Most of the porting m odifica tio ns were made to the exhaus t p ort and auxi liary ex ha u st p ort areas. Other motor changes include th e additio n of Boyesen reed valves an d a Pro-Circui t ex haust p ipe wi th Bake r u ses the re lia b le ICO odome ter set- up to ha ndle ti me kee p ing. ICO also offers bolt o n clocks a nd co m p uters. R id in g the YZ was pure p leas u re. What impressed us the most wa s th e easy-to -use motor, an d th e rear di sc b rake. First o f a ll, th e m o to r w a s extre m ely ma nagable for a ll types of en d u ro si tu a tio ns . It p ulled ex tremely well at low RPM and . rarely, if ever, fell off th e p ipe in those lo w -sp eed , engine-boggi n g sections. The increased bottom-end power from th e porting, pipe and ree ds, combined with th e six-s p eed tranny, made th e Yamaha extremely potent o n the trail. It was easy to ride fast on tight trails and had