Cycle News - Archive Issues - 1980's

fo ul in g th e spar k pl ugs, th e' va lves a n d va lve guides. Since TEL represented a n in expen sive wa y to boos t gasoline octa ne, engine d esig ners set to work on ways to prevent destructive lea d fo u ling . In th e p ro cess, it was lea rn ed that .a lead coa ti ng cou ld act ua lly be be neficia l; that a lead coating preven ted ac tual meta l-to-meta l contact be twee n theexhaust valveand valveseat. Asengine design evo lved , des ig ners took advantage o f th is p ro tec tive lea d ~a r ri er , a nd devel o ped valve m at erial s th at relied o n leaded fu el. Motorcycle engi nes in parti cular ca me to rei y on -Iea d to protect th e ex ha us t valves, since air-cooled hi gho u tp u t m o torcycle engi nes run h igher valve temperatures th an wa ter- cool ed au tomotive engines . Ab out 15 yea rs ago, tw o th in gs happened th at cha n ged th e future of TEL as a gaso line additive: automotive em issi ons reg u la tio n s, a nd increased awaren ess o f th e toxic effec ts of lead. In the earl y 1970s , em iss io n s regu lat io ns encroached on a u to motive d esign, a nd th e a u to industry d evel o ped ca ta lytic co n verters to scr u b ex ha us t emissions, Un fort u na tely , the lead co m pou nds th at coa ted th e valves and ex ha ust tract would also co a t th e p latinum ca ta lys t ele men t. rendering the ca ta lvs t in effect ive. But the catalyt ic co nverter was th e o n lvexpedient piece o f hardware th at co u ld bring exha us t emissions into line, and th e obviou s so lu tio n was to rem ov e TEL from g asoline. In March , 1970, the auto ind us try began a crash program to ada p t engines to o pera te on unleaded gasoli ne. About th e sa me time. th ere was considerable publ ic fu ror over so me ch i ld re n wh o had su ffered brain damage from ea ti ng ch ips o f paint. Pa int formerl y contained huge am ounts o f lead, and to prevent injuries resulting from ea ting pa int ( t), the governm ent banned lead as a pa int additive. Since lead was already a n evil su bstan ce in th e eyes o f th e publ ic, th e Environmental Protect ion Agen cy (EPA ) enco u rage d th e development of un leaded fuels . Metal techno log y had co m e a lo ng way in 50 years , and that flurry of tes ts conducted in th e early 19 70s showed that lead primarily protected 'th e ex ha u st valves. The lead coa ting on the va lve and valve seat had ac ted as a ph ysical cush io n for these com ponents, and had ensured a tight seal a t th e exhaust valves. Surprisingl y, th e intake va lves were unaffected, si n ce they weren't subjected to the searing blast of exhaust gasses. To ena ble four-stroke engines to run on un leaded fuel . technology was dev eloped to harden the valve seat and the face of th e exhaust valve. The other wear factor with unleaded fuel was valve rotat ion. With leaded gasoline, th e va lves wer e en g ineered to slow ly rotate in their seat with every valve cycl e. Thi s rotation en sured that th e lead co a ting would be even on the face of th e valve, a nd prevented localized lead buildup o n the underside o f the valves . With un leaded fue l, this ro ta tion meant the ex haust va lve would scuff against the valve seat and increase wear. For modern engines d esigned to run on unleaded fuel, th e exhaust valves are designed to not rotate: th e valve seats in exactly th e same posi tion with every stroke. Okay, so w ha t about two-strok e en gines run on unlead ed fuel? Si nce the m id - 1970s, mos t two-stroke motorcycles h al' bee n excl usively off -road m achi nes, and exempt fro m ex haust regu la tions. O f course, two-stroke engines do n ' t have exhaust valves no p roblems there, As it tu rns o u t, • lb. 0111)' lWQ.st50k6.titlSoig JU . hat-r-cl,. - o n leaded fu el a re th ose used for co n ti nuous rp m, high -load service, ' like genera to rs a nd o u tboardmotors . For motorcycle app lications, the continuo us o n-and-off th e throttle involved in riding enables th e engine to receive adequa te lubr ica tio n from premix o r injecti on oi l. By the late 1970s, the technology for mak ing fo u r-stro ke engines live wi th unleaded fue l was firmly esta bli sh ed , a nd manufacturers began specifica lly recom me nding lead-free gas to p rev ent lead d eposi ts on the spa rk p lugs a nd ex ha ust tract. Running w ithout lead Wh ich lea ves a big u na n swered questio n : wh a t ha p pens to the motorcycles d esigned 10 r u n o n leaded fuel if th ey're forced to d igest comp lete ly u n lea de d gaso li ne? • Imag in e life as a n e x ha ust valve. Th e spa rk plu g fires, a nd yo u ' re m ashed aga i nst th e va lve seal as co mb us tion pressure blasts th e p iston d ow n th e cy lin de r. Just as th e p ressu re let s u p , th e cams haft jerks yo u o ff yo ur sea t, a nd holds yo u in m id a ir to en d u re a swirl ing in fern o o f ex ha ust gasses , You r sea li ng surfaces heat to over 10000 F, T he p iston co mes rushing up , a nd just bef ore it h it s yo u, th e ca ms haft re leases its . hold, a llowi ng th e va lve spri ng to p u ll yo u back o nio th e sea t. Life's rough for ex ha us t valves. Fo r engines desi gned to ru n on leaded fue l, lead form s a p rotective barri er aga in st th e ra vages o f co m bu sti o n . Lead provides heat in sula ti on , lubri cation, a nd crea tes a su rface tha t m et al wo uldn 't rea di ly adher e to . T he sea ling su rface (face) of an ex ha ust va lve runs hot : a ny where from 600 0 to 1300 0 F, d epending o n engi ne speed a nd load. When va lves d esigned fo r lead a re stri p ped o f th eir lead coa ting, th is h eat , co u p led with co m b us tio n pressure, ca n actuall y " we ld" particles from th e valve sea t o n to th e valve face. Thi s proc ess sets up a destruct ive cycle: co m p ress io n is lo st th rough th e imperfect seal wh ere the part icles were rem ov ed , a n d co m bus tion pressure forces hot gasses through thi s juncti on, m aki ng it ho trer a nd we ldi ng mo re m etal onto the valve face. This welding ultimately ca uses wart-shaped formation s o n th e va lve face, With th ese m et al formati ons on the valve face, th e real trouble begin s. Since th e welding took pl ace under heat a nd pressure, th ese formations arc hard, typi cally testing at o ver 50 o n the Rockwell scal e. Of co u rse e ng i nes designed for lead relied on valve rotation to keep lead deposits in check, so as the val ve rotat es, th ese welded-on formations m ove to o ther a reas of th e valve sea t. Once in a new location, the va lve slams open-and closed to grind th e formation s against th e valve seat. As th e valve sea t decay s, more m etal burns o n to the valv e. Once th e wart-shaped formati ons reach a certain size, th ey ca n be burned down bv the heat and flow o f the exha us t gasses. Wh en bl own o ff in a rush o f exhaust gas, these m et al pa rticles are direct ed a t th e valve stem, prom oting wear within th e valve guide. T h is welding. burning, grinding and blasting ph en omen on is kn own to p owerpl ant engineers as " vain' recession. " For th e motorcycl e owner, valve recessi on means p oor valve seal ing, a loss o f power, increased exhaus t em issio ns, and decreased fu el eco n omy. In a wo rst- case situa tio n , as valve recession oc curs, va lve cl eara n ce is taken up, the ex ha ust valve runs out of clearance, is held off its seat, burns, breaks off, and destroys th e engine. Motorycle engines designed to run , __ 8A Jaade",fw~"Jaade",fw.I, Pn;i~. T he alternatives There has bee n some specu lation that companies will market TE L as , an addi tive for co ns u m e rs to ble nd wi th th eir gasoline. -No wa y. Un for tunately, TEL is an o rga ni c compou nd; its organ ic nat ure is what makes it soluble in gasoli ne (another organi c compound - after all , the stuff is made from o ld dinosaurs ). As an organi c compo und, TEL is also readilv absorbed into th e bloodstream of h urn a n s. The problem is th a t TE L is ext remely toxic, and sma ll quant ities cause extensi ve -d a rnag e to the ce ntra l nervous sys tem . On !): two co m panies arc produci ng TEL Du Pont and the Et hy l Corpora tion - a nd both have stated that rh e v are u nwi lling 10 accept -rh e lia bilit v of p lacing TE L in the. hands o f co ns um ers. ~rhere's a'wides prea d mi sconcepti on that ce rta in gasoline ad d iti ves will so lve th e unleaded d ilemma . A number of cv lis ts kn o w th at lea d so meh ow " lubrica tes;' th e valves, a nd assu me th at a gasoli ne add i tive advertis ed as a " va lve lubr icant " w ill su bst irute for lead. Actu ally , th ese p roducts p ro vid e lubrication fo r th e in ta ke valve g u ide (a nd, to a lesser degree, to th e p iston rings a nd to p end), a nd o nce burned , o ffer no hel p for the exha us t valve. O ils a nd lubrican ts sirnp ly ca n' t ad here 10 the face o f the ex ha us t va lve a t operati ng tem perature. So how much lead is requ ired to protect a n en gi ne desi gn ed for leaded fue l?' Su rprisi ngly, n ot much , In th e heyday of T EL, refineries would add as much as fo ur o r five gra ms o f lead per ga llon o f gas: T ha t's a lot ; i n 1970 (the pea k year for lead ) th e oi l refin eries adde d 463 millio n p ounds o f lead to gasoline - j ust for tha t yea r a lo ne! Th rou gh th e yea rs, th e EP A ha s passed vario us regulation s for maximum lead co n ten t. and a s m enti oned in th e open i ng o f th is a rt icle, a new m aximum o f ' 0,5 gra ms -per-ga llo n (g pg) goes in to effect o n Jul y I. Next J anaury, th e .n ew sta n dard will be a maximum o f 0.1 g pg . Is thi s enoug h lead for the ex ha us t valv es 10 su rvi ve? iR W Valve Division is a major supplier of va lves to the automotive a nd avi ation industry, a nd has a subsid ia ry in J apan, th e Fuji Val ve Co . Ltd" which supplies va lves to Honda , Yamaha , Kawasa ki and Suzuki, Acco rd in g 10 Tim Soucek. Manager o f Tech n ica l Administ ration for TR W , " We' ve found th at eng i nes design ed for lead don't require much , Based o n o u r laborat ory d yn o testing, th e: 0.1 g pg sta nda rd shou ld p rovide enoug h protecti on for valve co m ponents. If a ny th in g , we're happy a bou t th e new standards; we've found that in so me cases lead deposit s ca use s co rrosio n o n the valves a nd sea ts, which G ill lead to weakening o f th e valve, m etal fatigue and valv e failure. Again, our co ncl us io ns a re based o n laborat ory test s. not o n actua l veh icle usc." Part o f th e problem in determini ng th e co n seq ue nces o f unleaded fu el is th at th ere has been no co ncl us ive test ing. Mot orcycle o w ne rs who hav e m a chines thai require leaded fuel typi call y us e leaded fuel : and running a n occasio na l tank o f unleaded gas won't co m p le tely re m o ve th e p ro tecri ve lead coa ting from th e valves, Th e EPA has co nd uc ted , tests with military and posta l fleets, running leaded fue l vehicles strict ly on unleaded fuel- but these were water-coo led ca rs and trucks that have litt le in co m m o n with motorcycles. The fact is, th e 0.1 gpg standard is now law , and as of next January. th a t's the best grade of leaded gas that will be available at filling sta tio ns. Currently. aviation gasoline and ra cing gasoline are exempt from the lo w-lead sta nda rd - bu i these fut ls are expensive and ge nera lly a re n ' t ava ila ble at corner sta tions. The danger is with fut ure regu lation: t ha t th e EPA may declare wa r on that last l Oth -o f-a-grarn. If lea de d gasoli ne is comple tely unavai la ble, cars and motorcycles designed to ru n on lead ed fuel are in trouble. What can be done Let's examine the worst case: suppose the arguments for engine life are ignored by the EPA. and it's J anuary 2, 1988 - the day after leaded gasoli ne is forever ba n ished from th is coun try. \\'hal can you do to p rot ect th a t .o ld H a rl ey (o r BSA. Norton , Triumph, Mo to G uzzi. Ducar i, L,verda _ .. in fac t all pre-I 970 motorcycles)? . If the bi ke ha s cast-iron heads. th e a utomoti ve indus try developed a process ca lle d "ind uc tion hardening ," wh ich ha rd en s th e seats to help p reve nt va lve recess io n , It is po ssibl e to inducti on -h a rd en a m ot o rcvcl e head , bu t it 's a tri cky process, a nd th e head would have 10 be co m p lete ly str ipped. A nother possibilit y isTo hav e a machi nesho p in stall valve seat inserts. Motorcycl es wi th a lu mi n um cy li nde r heads a lready use in serts; iron h ead engi nes ca n be m ach in ed 10 accep t th em . This is expens ive, but proba bly th e best so lu tion for the scats. T he va lves themselves a lso need repl acem ent, p referably wit h the la tes t-tech nology Stell ire-Iaced stai n less steel va lves. Ther e's so me discussion that ce rta in m anufa cturers - BMW and H arley-D avidson in pa rticu lar - will m arket a kit for unl eaded co nvers io ns, co ntai ni ng the appropria te va lves. seats a nd so on . If not, a co rnpet eru m ach ine shop ca n , a t co nsidera ble expense, m an u fa ct u re a va lve to sui,t a ny motorcyc le. Aft errnaker co mpa nies m a y mar ke t s ui ta b le va lves . T hen th ere's the issue o f valve ro tati on. Thi s o ne's to ugh. For so me m ach in es, th e geometry o f th e valve tra in would ha ve to change to prevent rotati on. Other s co u ld ach ieve it with differ ent val ve spri ngs a nd retain er s - but th os e would be in th e minority. What 's likel y is th a t own ers will hav e to a rr a nge for valves a nd seats . . . a nd hope for th e best , knowing tha t engine l ife will never eq ua l th at with leaded gas. • (Co ntin ue d n ext w eek ) Will the EPA go too far? There is-evidence that removing some of the lead from gasoline is a good thing; less lead will enter the atmosphere, and there will be fewer engine lead deposits . But based on their research, the EPA has expressed its intentto completely ban lead as a gasoline additive. However, the EPA has not yet made a f inal ruling, and has conceded that " Som e trucks, farm equipment, boats, motorcycles, and off-road ma chinery may face a greater risk if all lead is eliminated from gasoline , . ,.. That's our cue! There 's a good chance that motorcycles which require leaded fuel can live with next January's 0,1 gpg limit; below that level, engine damage is almost a certainty, Write down your needs as a motorcycle owner, and send them to: The Environmental Protection Agency Docket No. EN-84-05 401 M Street S.W. • ~ ~"hi~~on~ ~.~. ~~6,~ , ,

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