Cycle News - Archive Issues - 1970's

~ Power of Silence (Continuedfrompage3) 1 openthepipe curve is In eachin.case the on facing page. dotted R 0> ~ o ,; ~ 1!1 S ~ W 13 ~ s~own. lines the device curve, In soltd line. The verti~al scale indicates horsepower while the horizontal scale denotes the engine speed (r.p.m. times 1000). Again representatives. ·of several of the manufacturers were present, keeping us honest. I've heard it said by people who should know better that you can't measure two-stroke performance on a dyno. This just isn't true. Not only can you measure performance very accurately but on setups like Axtell's, the tests ::re repeatable. In any kind of scientific testing repeatability is the key word. U you can not set up the same conditions and get the same results, you can never be sure just what caused a change. Axtdl measures and records everything. even room temperature and barometric pressure. The main variables. of course. are the devices that ,:"e were han..Jing onto the ends of the pIpeS, but there are other things to be taken into consideration as well. The most importaut side consideration is the engine condition. If the engjn~ is badly out of tune. the tes~s will be difficult to repeat. The Sachs 18 fairly new and was in close to perfect tune. Timing and carbureti0I! were spot·on and it could be started WIth half a kick at any time during the tests. (For those of you who have read the advertisements claiming 17 or 18 hp, who wonder why only 13hp was measured on the dyno. I offer you"MT. Axtell's surmise: "Maybe they measure horsepower at the wrist pin.... Or maybe they lie a little. The Sachs 18 stock and goes as fast or maybe a little faster than an other stock 125.) We were not quite so fortunate with the Yamaha. Its timing was a little off and the camuretion had been adjusted to compensate. Although this does hun test repeatability. there is a side benefit: The Yamaha's tune probably comes closer to the tune of the average dirt bike. so the results for prospective WILDCAT••• a reliable motlrcycle owners will be similar. Both bikes were strictly stock with the exception of the exhaust pipes. For the Yamaha we had a Bob Bailey pipe and and A&A pipe. On the Sachs is a pipe which is close to stock but has been built by K &: G Engineering so as not to burn my leg. It has a slightly larger than normal stinger which seems to help low end performance quite a bit. Now let's look at the devices individually. TORQUE ENGINEERING SILENCER/SPARK ARRESTER. This devices is still in the prototype stage. The spark arrester has not yet been approved. It is quite. co~pact :,nd provides fairly good silencmg..It 18 a little bit heavy and fell off durmg the test. The -most serious difficulty is that jt causes a 3 hp loIS at 6500 rpm. The Torque Engineering Silencer'is bigger. and does not have the spark arrester feature. It also does not quiet bike any better than the smaller unit!' It too " IS /\ .' 17 J , 11 ,. •I ~ , , I ". 2 . " I I ! I I i : ! I I I I ' , 'I ; : 1/: : ': ·ji--If '. , I i Iii I , • S :D 2 I i I ! I • YAMAHAoT1-eWITHA.A' '\ S ... i 'i I " " . . .. IT iI ~ ! , ~ " " " , iI h ----":7 If ; /1 r 1 .~ " " !~ 't'. CHAMBER AND SILENCER ! I • •AAK ARRESTER: NO PRODUCTION ITOI: YES I QUIETING, • De I LEVEL' • De : , i I .- _. ... - .. .. . 1 ~ I 4 3 s RPM X 1000 • • • 10 BII.s IIld plrb lvailible ilamedlately. Diller inquiries invited. ,,'1--1-+-.+,--+--....1---+-+-1I, '21--+---+-- ---+;--,,~4-+-t" I--+---+- • ~-L-f-Ir":-'~-+-i-+-tsl--L--#- !' • f--i-+1f- I' 21: 2 zL--!-.---!.--,s!-:.--±-.--,!,,---,.!---;.-:,:,., RPMX-1ODO causes significant hp loss at 6500 (2 hpj. It is still in development stage. The BASSANI SILENCERS for the Sachs has a nice tone but doesn't quiet very much (6.3 db)'. It loses about 1.25 hp at 6500 rpm, gains a little in the lower-middle tange. It seems well constructed and has a replaceable element. The Bassani Silencer (Yamaha). Although essentially the same device, there was a considerable change in the performance, much more quieting (14 db) and. a considerable honepower gain in the mid·rllDge (2.25 hp gain at 44(0). There is negligible loss at the high end. The Bassani Silencer (Husky). On the Husky. the silencer did little more than take the edge off (3.7). It was not tested on dyno. HOOKER HEADERS SILENCER SPARK ARRESTER. We received two devices of similar construction hut different size for the Yamaha and the Sachs. They were the biggest and heaviest units of the bunch. but they are still in development stage. The device did a good job of silencing the Sachs and came closest to making it street legal. hut it cost about 1.5 hp at the high end. On the Yamaha substantial horsepower was gained in the mid-range. bnt some was lost at the top. It didn't quiet as well. On the Husky. it only produced 3.3 db of quieting. In its present configuration. the device would be difficult to keep on the bike without special mounting ~gements. J &: R PRODU~S. J&:~ sent us silencers with two different SIzed corcs. spark arresten in two different s!zes and some combination units. Taking the silencers fint. they were the lightest units we received. They come in two core sizes. The small core variety was fitted to the Sachs. It caused about 1.5 hp loss at the high end, and did not provide much quieting (7 db). There was a small gain at the low end. Now get this! The same type of unit when fitted to the Yamaha gained almost 1.5 hp through the entire mid range from 3500 to 5500 I}'m. It lost less than .5 hp at the top (6000). It provided 15.3 db quieting. The large cQl'e silencer ~~rked even better on the Yamaha. gammg a full 2 hp over much of the range and losing an almost immeasurable amount on top. Cost in quieting was only 1 db On each of the graphs, the dotted line represen1S the pow. of 1IIe bike with an open expansion chamber. The solid line respresen1S 1he power wi1ll the same pipe fitted with the test device. ATRACO WlldcltDlslrlbulor: FRANK WHEELER 659 W. Laaclsler Blvd., Lane. . .r, CI. HI·PERFORMANCE EQUIPMEJlT (885) 942-2312 PO 11I12611, Pall' Verdes Pen., Calif. 98214 ethe specialtyit Jawa/C-Z,] spedalze machines. The Bike Shop 2021 Via Burton Anaheim, Calif. 92806 , • (714) 635·1450 IOn State College Blvd. 1 blk. north of Riverside Fwy.1 SPECIAL LONG FRO(,NT . ENd ' (213) 894-9218 WARREN WILSON MOTORS MOTORCTCLI ilolli - ilRVICI SOuth of :\ordoll in So'puh t'dll. ('..hf. 9000 SEPULVEDA BLVD. RICKMAN BRIDGESTONE Ir lleCiSiOft Cycle For the rider that demands the best in porting. pipes, service & sales. 14727 Hawthorne Blvd. lawndale, Calif. MAICO E.C. (213) 676-6123 JOE ST.P IIITO TN. PUCH ·s ClltCL. TRIUIIPB·BONDA·BSA RIDERS· The Fiust II MotwcYcle Stnice 2040 5. Main St., santa Ana, Ca. ,Ph: (714) 540-0033. 1Ir--.-,--,--.-,..-,--.-,.. 1I1-:--+-+-1---.:+~+.-+---t-+ HUSQVARNA 171-:--+-+-H-l~lV--+---t-+ 111--+-- Distributed bJ 161--+- Med-International 4190 Palm Ave" La Mesa, Calif. 92103 SU"" , ---- ---' I , -'--j SACHS ._--, aecassorias parts & I , BMW Specialties 411 West Whittier Blvd. Montebello, Calif. 90640 (213) 724·9474 SILENCER SPARK ARRESTER TRIUMPH, ' H·DGLlDE, SPORTSTER Seamless, ground 1015 tubing: 4"·12" $18.50 - 14"·24" $19.50 Seamless, ground 4130 tubing: 4"·12" $28.50 - 14"·24" $29.50 Chrome Plate add $14.00. r 'Norfo!]) ' . QUIETING: 12.3 I _~~~L~~?. -_. --~--·_-t ~ s i'---ll----i -- - -. ~- --- ---I LIGHTEST SUPEIB,rE ~62 P.df'c C •••4. ••st 2073 W. Plclflc Coast HWJ• .....1lI. CI: PII: (W) 321-3818 YAMAHA plus handling. 1----'-,HAPl'ROVEO' NO m Open 7 days $10.00 deposit, balance C.O.D. -f ~-L-I-''~~~~T'UITH~KER~~ -+ fOlfTAIIA Yamaha-Sach's- 9008 Sierra Ave. Hodaka-Maico- Fontana, Calif. CZ parts - Sales- S~ic~ (714) - 822-2252 , 1 3 4. 9 RPM xTOOG J•••• "'I'~ s.,s ,. '.s.,••ee "Her .r. De.ler'" We carry all types of insurance coverage - garage Ilabi I ity fire - theft & dealer bonds S••• Up T.251 JOHII •• MAYliARD IllS, 3441 .... A"., L.A., Ca. (DI)I3&-52ll , . ." ','

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