Grassracing Summer 73

7/28/2019 Grassracing Summer 73

1/11

.). YAMAHA

GRASSRACINGSUMMER '73

lt lYemaha lntemat ional Snowmobile Service Dept. July 17, 1973


2/11

WARNING

Thi$ tIook is d ~ l J f 1 to provide info'mIIl ion 10 the f OC.. - who i. intt'fE'Sled in ob t. in-ing I> iitt.... perf ormance from hi, production Yamaha Snowmobile ,Some of lhe modifica tions in this t>ookle l may ,horten the life of me m"""ine.YAMAHA INTERNAT IONAL CORPORATION can no! be held respoll,i ble fordamage 10 the engine parI< '" chm,s as ' .. .ult 01 modifications pr


3/11

WEIGHT REMOVALSl


4/11

Chain and Sprockets; On the 29 2 a doublerow chain i, suff icient , and on the 433, atr iple row chain i"ufficiem. Don'! forgetto cut off the ~ t r a sprocket roW$ andinse n . '1''''''' ' in place e l l ham.DRIVETracie An inner drive track made of anextremely flexi ble material should be used .Gales Rubber Compeny and GoodyearRubber Company manufactur. trackl ofthi. ty pe. Care should be taken that th edrive sprocket! are matched to th e type o fIrlll: k used . Gates inner drive t r a c h anddrive components Can be obtained fromK. IIll1 81oo Engineering, P.O. 80 x 8154,Grand Rapids , Michigan 49508, (616)5343661. &/t- - , . r-f2 _::tt:. C; ISuspension: There I re Ih.H choices ofsuspension lVi'll ..... ilabla.1. I....tall bogie wheel. and link plates,either directly in Itte Challi., or in a subframe which is bolted to the challi.2, Install a "bogie rail" type IUsperl.ion.Kl lamazoo Engineering ma""faetur. . a suspension of Itti. type called th e Saondblalter,which is available seporltely or in I complete gra. . racing kit .3. Bell Industr ies Griswold (1 OB I Highway 3B E. at Junction 61. St. PaU, Minnesota 55 109 ) manufac tur. . a new type ofsuspension . uitable for drag racing use,called the Fiex-O-Bar. This is also availablees a complete kit. t;:...J:Z 5Spindles: If th e ski. drag on the grounddur ing acceleration, use th e shor t est available Ipindlel (Part Number 856-23853-1000). These spindles mHlUre 10mm from

the ~ m of the ski pivot bo h ho le to thefli t " IN . bove the hole.

ENGINECompression: Hi""'e. compression ~ n beu,ed 1(>1" drag racing only , due to tha sho rtlength of the race. This increaMd comp"'$$;on i, in addition to th e engi" " speci ficatio ns shown in th e incHvidual 8flginespecifications, end .hou ld not be uwd for" ,y race longer than a drag race.To raise Itte compression, ClJt lmm (0.040")from the cylinder Ilead gasket surface.For operation at a ltitude1 above 2,000', anincrease in compression will help to reogainpart of the power 10$$ . Cut ' " additional0 .25mm (0.010") for each thOU$llnd feetabo .. . 2,000 feet altitude.Cut 00 more from the heldls) than correspond. to the lowest altitude that you willrace at . " you race at widely diffeoringaltitude1, yo u may desire to have differentheaciJ for each altitude. Do not exceed200 p..i. cranking prlllSUre.

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5/11


6/11

Belt : On the SR 292 only. a standardIB061 belt may be used for d,ag no,i ng.The standard belt, being th inn. , and mo,eflexible, i. more efficient than the SR (820)belt ,When you chose to u. . the 806 belt in' tearl01 the 820 belt on the SR 292, check the806 belt to be ,ur. it m ~ . . with thetel erane. . lor the racing (8201 !>ell. Thelength. and tolera""". a,. '

File the Ilat e


7/11

s....u.e of ...nout ~ - .o l l l ndduri", the ....n .- . . . . . . .. it ill not rKOIn""'oded 10 modify tho SA 6438 ongiIw.Ua " " ,., . if you "- . . . . no ->ous . .lI'abl""b ' f"! , ....t if ....t only if y felltN l e little ....... ~ ....nsiWlifi.CoWltl., imlln:Mo you. ......11. you CoWl II"/'the loI ' - ing -..ggesti"....

SA 6438

Meximum honepwor rpm B50CI

Cylinder Held: Cui 0.25mm 10.010")'rom 1M gasket .. . ,1.... Re'er10 CylinderHeld Modificati on . pg.6 .

E ~ a. .nbw : II you h. . . . . .1Ndymodiroed your a>qMtItion m..nt .rs ~ing 10 SR BulIWn No. 17. you .-d only.....- - .t -.Idltionlll IOmm10 . " 1313r1from th I hud p i ~ n. ...-t_iIII ......Idw owed !Tom tho fitR 80mm 01 Itp i ~ vohich tIM no ~ Relocale th I~ hooks il .. WV . The IiniohtdJIipe will "" di-t from tt. . origi. . . .equipment (unmodiIiMl) p ; ~ ItIOWI'l..-

"':"OV' 11 .....It l . " : t lOlO" l ' f

CIIT otr

, .J,., ,u.t ..I

Piston : ~ th I itIt1l


8/11

,,,

Cylinder: Rai'" the nh aust port to 35mmfmm tile lop of the cylinder. Refer toChroom a l ~ Cylinder Modificalion, PlI. 7.

I, I,, ,t'. L.1 t ~ H ! \ '.. "F " ~

E, pan, ion Chamoof: Remove 50mm 12.0")from the ""ad pipe lbot...,.", the cylinderand the first c""el on each e' p" r"l$ ioncham t>e 10 removethe therp edge (sar>ding with a medium gr;1. .ndpaper is ulually enoo!t ,

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9/11

m Ill! ..... th Jt .11 1)011 joinu. . .m.!dMd 10 ell".;. . . . . "fllIP'" th at . . . . . . . .1Iow Don'I owtrlook gHkm (cyIi...._ "",,all, ...-b gMkm, etc.) ~ mayutend into "_ P' g I, Trim oft . ,y- ' ;eI thai Iand IftlidlI m. 1)011.Q'lro"" . t e d Cylinder Modlflcalion: Thamodi!H;Jt lon of c;!Irome p1. ted eylinde be et.d


10/11

and the engi"" rpm doesn't rise drMticallynear the end of the rac. , Ih. gearing i."""eel. II lhe mark il ~ m o v e d . but the""91"" rpm ' ;eck Lin: Memor ize 0. copy the follow-iog check lin. and 9" over il before eachrace day.

Track Alignment: Track alignment has .,eff e fuel for ....er. 1 run. Th i.hel"" to IlVoOd _ation 01 the '""I,Carburetor Fuer Level' If thrott le r


11/11

ENGINE _

CHECK LIST

IgniliO

Grassracing Summer 73

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