Cycle News - Archive Issues - 1970's

"" 1 I:'i ", over the small core unit. On a horsepower-per-dollar basis this unit has to be the best hop.up value going for Yamahas with Bailey Pipes. The J&R Spark arresters are actually Horstman-Krizman spark arresters which J&R modifies to fit various machines. They come in two internal sizes, 24 cfm and 60 cfm (cubic feet per minute air flow). We tested only the smaller device on the Sachs. It was a flat disaster: it cost a full 4 hp at 6500 rpm. It did quiet the bike down to street legal requirements, but it had a flat, ugly ton'e to it. The same device when fitted to the Yamaha was not nearly so bad. It 19 TABLE II Motorcycle Sachs Sachs Pipe K&G Eng, K&G Eng. Sachs K&G Eng. Sachs Sachs. Sachs K&G Eng. hi , ,od Sachs K&G Eng. i i !I ' ''--'--i---# -+-'-f----I--+- Sachs K&GEng. ':[1"0;-'="';hi'"~ 11 10Hi Sachs ; : . " : - ,+ -:'I I - ;-+-~.--+f--,-I .: '--i--+-+-+-+- +. , 1 Bob Bailey Bob Bailey Yamaha i / K&G Eng. Yamaha Yamaha . ----j-f--+--+_ Bob Bailey Yamaha Bob Bailey Yamaha Bob Bailey Yamaha Bob Bailey Yamaha Bob Bailey Yamaha Husqvarna Husqvarna Husqvarna A&A Stock Stock Stock Husqvarna Stock Husqvarna AJS AJS Stock Stock Stock 1 •_ ! /; I . ' I r , ,..' SILENCER SPARK ARRESTER: N O ' 5 • >---+-7-1--;- ~=~:'~T~BM: ~ I: YES I NOISE LEVEL: M DB 1 .. ... ' +-+-- ~. SACHSWITHBASSANI __ _ ' : . ~. .. I . _ ••• .~:::. ~: Z'--'-3'--'.---e---.!------,7e-'-'-'-!,-----±.--;,""0RPM x 1000 (2.5 hpj but it gained'a bit in the mid range (1 hpj and it was not nearly as nasty sounding. It brought the Yamaha close to street legal requirements. With the 60 cfm spark arrester, the Yamaha gained all the way from 3500 to 5500 rpm up to 2.5 hp. Loss at the top was less than .5 hp. Good but n.ot spectacular quieting. This is another good hop-up value. IThe J&R Combination silencer and spark arrester was by far the best unit tested on the Sachs. The power curve was almost unchanged: a little gain in the mid range, a tiny loss at the top. There was moderate ,quieting - 1 db worse than street legal - a good tone and it has an approved spark arrester (60 cfm Krizman design). It is also quite light. This unit was also tested on the Husky and pr,ovided 6 db quieting, the best managed on the Husky. A&A MANUFACTURING. A&A sent us an expansion chamber to fit the Yamaha and a silencer to fit the chamber. They also sent a silencer to fit the Sachs. Neither unit was very spectacular as a silencer (3 db quieting on the Sachs, 3.7 on the Yamaha, both a long ways from CHP requirements). The A&A unit on the Yamaha was unusual in one respect, however: it ::0' 2 ,. ., ;~ .~.:: : ~ 0 :.: '7 ~~':"':-+-..jll'+J''\ ,. -+:.:.:.tI---t-:...::.~:.+ I Quieting none 8 dbA 12.7 15 " 10 db 14' .. Z ,.. 13'r---+--++7-;+-1'- +--+--+--+-+, ..J i·;· 161 ,'" I , .. 90 dbA ~ w I. 90 dbA 10 db 93.7 dbA 11 db >C,) 1':..:..--4.---II---';-+---1---1--+---+-+- '2 ! I , I-~~'- YAMAHA I I Dn.e WlifH J & R SPARK ARRESTER t80CFMI , APPROVED: YES '1--4---1 PRODUCTION ITEM: YES 95.7 dbA 4.3 db 106 dbA 90.7 dbA None 15.3 db QUIETING: 15 DB LEVEL: 9108 57 -: illl :: ~. ~,61 .:C. ml 91.7 dbA "-_. 1 =5 2 3' 14.3 db • 41 RPM X 1000 89.3 dbA 91 dbA 15 db 93.7 dbA 12.3 db 92 dbA 14 db 98 dbA 99 dbA 94.7 dbA 93.1 dbA 3 db 4.3 db 5.9 db 95.7 dbA 3.3 db 95.3 dbA 100.7 dbA 97 db~ '0 our test bikes. In terms of-quieting, the Husky was the hardest to quiet, the Sachs was next, and the Yamaha was easy. With respect to power, the situation is reversed. It's hard to conceive of adding anything to the expansion chamber of a Husky and increasing the power. With the Sachs, the K & G Expansion Chamber is very efficient so only small power increases 16.7 db 3.7 db_ ::' ~-+!..: - ._'-.- 3.7 db ~ ~' J. 51==- == r-----. "I~~ . 5 -. '_iJ I ~ ~: ~ !==-~'" :D ~ 3f"+- - . r--+t--' '21 - - SACHS WITH TORQUE -- SILENCER!spARK ARRESTER ~ ::-:::-- : APPROVED: NO . PRODUCTION ITEM: NO . QUIETING: 10 DB ..::::..:-=- .f- -- ,--~- ·-:I.-·~I--"--~'-- _._-- 4 5 F r: '-1--' . , - - e: RPM X 1000 ~lg~ISE':E~~+E1~::..:~ ?~_ 1..:_ ~::: 3 :: :::;: ~ ~ NOISE LEVEL: 92 DB !. I- ._, =: are experienced. With the Yamaha, if you're lucky, putting on a silencer could be more effective than a $50.00 porting job. It seems to depend on how the bike starts out and how close to optimum the pipe is without anything on it. With two exceptions, all the accessory devices were held on with radia'tor hose clamps. The exceptions were the A&A unit which is held on with small springs and the AJS. Without exception, the manufacturers claim the devices will stay on. As an experienced enduro rider, I don't believe it. If 1 were required to have one on my bike when I f1I!ished an enduro, 1 would provide another clamp, to the frame or stick an 8-32 screw through both the device and the stinger. This doesn't apply to the AJS unit. It should stay on through several crashes. Hope this helps you to go faster quietly. " /I III II" c=_ f--- PRODUCTION ITEM' YES QUIETING: 8 DB 3 . -- 71=4-+-I'f=--...:.t-+-=--t-c:-I=+ 6~ ....,7( _ ~'2 2L.....J3'--l.-=-..:·~· ":':'-!c':"-:"=< ....::::::!l.:::--=·..~:t::.=-=:,~~ -1-l-' :. .. ::: ,.. t:=:- SPARK ARRESTER: NO . , 5• :a if 9~_~___ s ~12 6, 7 8 9 Dn-c YAMAHA WITH J & R I!:"- '::~....:::: SILENCER (SM. COREl ::: .':"j-'rlH-o8!""-.:.:+-l-SPARKARRESTER: NO ., t-'!-r-f-t-/o-h- , _, PRODUCTION ITEM; YES:'~ 10 LEVEL',~ ~;:: ,.: .. -'~:' .. ,. 7 .. - . • 1-:::::]::1::l+: --I;:::::t:~ . ·'QUIETlNG: 15.3 RPM X 1000 \ +.:.--~ "-'f-!.,,.L-.h-:;7_1!E~!=j.:;:j: . 5' ::: ~6 _:~- ~,~_ ~::_-<~-t -:::.: ::= -:~~I~-m their machines, so AJS, makes a silencer for their motocross bikes. It is a thoroughly professional job with an exterior clamp that goes on the frame. It only cuts the noise by 3.7 db which is not much but it definitely takes the bite out and makes the AJS pleasant to listen to. We did not have the machine available for the dyno, but Mike Jackson says it has been tested in England and there is little power loss. What have we learned? Well, it's not only possible to silence your bike, it's possible to gain 'horsepower at the same time, the problem is that you don't know which device will work for you and which won't. Now is the time for ~ .~ -=:: :~: : .:J.j:~~. ~r:::::: ~~W :D 52 3 4 5 6 7 8 9 10 R?M X 1000 some enterprising manufacturer to rent some dyno time and test his products with a lot of different bikes. Then when you buy a silencer you can get a curve with it that will tell you just about what to expect. There is one not-so-obvious conclusion that we can draw: The closer your bike approaches the limits of its potential and the better the expansion chamber, the less improvement you are going to be able to make with a silencer or spark arrest.er. We can see that from 13-+t-t+-l"'1"T+, ~~----t-r.......... '2:~ -.:J ~:~. _._- ._- ..:.:- :~;.; 1---'-- -- ......-t-.-..- '8!ii.F1 :< ~L7j', ..:: i:j ggB 17.:;-:-:.. '8 --- r"?c ~~-- _ -. _ .. .. h::-' .. , , ,- Iii \ , I • -.I:':":'I~!:: : -1::::::1=i ,. ~'-+-'-f----+J;..I-+--_+-'-f----I':::"'-+- ,:_~~. 11!,,---'-f---.:.::.j-"-"-f--/--+-+-+--+--+-- ,. >-.....j--'--+-J'-'I--+-+-+---+-'-'--e: /: ,-'Of-I'-+-+----j..:...:....+' .: '01'-'-=-+,.L-=+-_+--',+-_+--I_-+_-+_-I-_ '31:--+-+1--':+ I l' .I----j--+-+-h>....-II--+--t--+--t- 12 I-'-.....j--+~I+-+-+-+---+-'-'-f" I::--l--I-'.J. '-t--f-.--l--+--+-+ : 8 F.::+:....:..+-'-~-+-Cl\+'-+'-'-+-+-+1 7 101-=-.....j--J.l'l--+--+--I--+--+--l- 10 showed a horsepower gain over the open pipe over the entire range, ev~n at .the high end. This result however IS subJ~ct to some skepticism. The open A&A pipe shows quite a bit less horsepower over the range than the Bob Bailey ~ipe use~ for the ollier tests. When the silencer IS attached the Bailey 'Pipe and the A&A pipe are quite simila~ in perf,?~nce, so it looks like the sliencer IS Just one element of the pipe without which, the pipe doesn't, work. . AJS SILENCER. In England all IDOton;ossJiders.are...r.eqJliu:d tQ.silenc C,) 6.3 db 89 dbA W 10DB 90 dbA ~ I III I I . .. >--'T-+---i--'SACHS WIT.H J & R S'ILENCER- ~ ~ !. (SM. COREl 0; • :;; 87.3 none K&G Eng. ':.1 ,",) 1 i Noise Level 100 dbA 92 dbA J &R silencer (small Core) J&R Horstman/Krizman Spark Arrester J&R Combination H/K Spark Arrester and silencer Torque Engineering Silencer Torque Engineering Spark Arrester/silencer Bassani' Engineering Silencer Hooker Headers Spark arrester/silencer A&A Products SilenceI' None J&R Silencer (Small Core) J & R Silencer (Large Core) J&R Horstman/Krizman Spark Arrester (24) J&R Horstman/Krizman spark arrester (60) Hooker Headers spark arrester/silencer Bassani Engineering silencer A&A silencer None J &R Silencer J&R Silencer spark arresrer Hooker Headers Spark arrester/silencer Bassani silencer None AJS Silencer K&G Eng. II 1 . " ' !.;:! !;: 18 Device I 8 _:-::: ':::c" =-=: ., ,11', .- :~ :~~-- f- 7 : ._~- --- . ,: -~--::=r.1 :.._. - 5 I---- 2lI 1 5 .,.. SACHS WITH TORQUE '~-"- SILENCER t.: 1111-I~SP!A!R!KIAlRlRlEST~E:R;,. NO:JII 5" 2.Ptr5r~ PRODUCTION ITEM: NO QUIETING: 10 DB I .!"---'--f---oH ~~ . ~~ ~~~~~ !~1' L:~ 1~~WIT;J.-~ --_.N--. 1=::::= '~""'_ --:-1 r:.::..:.t=.:.-j':'·:":f-'+.::=--r:..:::. : :-~:. : l-----j~4-,--_+.,,-+ t, 8 r : .. _.--:..:.:If: . 81== _. ::1;'::.. != LEVEL, 80 De 4 _'_'__ 8_~-L":""'!";~ - . .- ~ __ ,., _," ._.- ., ::::, --C'" !I ::'::'~?l;'-': = .. __ "' ../3,'·· ~, .... :~~: ": :APPIIOVEO, YES .:_:-:.,.:-.;PROOUCTIONITEM: YES '_'.'_0I'QUIETING:12.7DB '1 NOISE LEVEL ~ .:. ..-_. -- ._:-:...:: .... 81.3 :.....:1~. :=r.::-:, __.. _+. --I· 6~f:-:.:·: .,.:. ,f -'J-I ~~~~~~~~~.:N~ES f-.':.:' . f-::':':: , HORSTMAN-KRIZMAN SPARK ARRESTER: (24CFMI ,.I ,. on.e WITH BASSANI ! ::..:..:.t:: •= - YAMAHA SILENCER :~," - 7,.. ._. L~'~_.::: QUIETING: 14 DB LEVEL: 9208 =~ ::.:..:1= ~--==r:.: i_- _ ::....:.:.F= -.'':::~ ::.:. ." 8 ~=Jr,:.=-i':":'-+--i--+-+-+===+=F i· ~ ~1~:,:~c~;,~:~:,~-=.~~;~_:":4:::.;=r=;~=o,;: _ _.J F . -- ;'2'- 3 :"::"'F 8 8 .=~~ •

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