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/125874
Diagram 1 (magn.eto.ignition generator) . r: '- (electronics bo xl '-'j-'- ' l I I I Mill head .0 2 0 I I I (spark PIUg)..l. Diagram 2 o With reed (no boost ports, stock pipe) • St ock 125cc Endu ro 1&.0 D IN HP * E.C. work s engine 56x54 o E.C. works engine corrected to 54 x54 24 22 W 1 1 / - \\ .\ / V- I If b I 'I I: 14 1 // , "" 13 12 W l\ / /' ::> 16 :> 15 u, / \ .... 2I 20 19 18 17 o A <..f) 11 0:: 10 . V ~ \ r-, 1 "'-.. I. o ~ \ I. / V y/ 6 5 -, <, 'f I7 I'\. <, ~ 2 11 1 '" I 4 3 2 I - 7000 11 0 0 0 9000 R.F?M. .l , t 3'60~6 I 6s '6 2 ,.2 ~0 ISO '[gD Diagram 3 DD Boost ports MX ( 28 Reed asserrb tv 1 * 23 0:: Boost port ) Endu ro ) ( ) D'D DO Diagram 5 Diagram 4 have a problem, eve n with the engine in stock form it's no t very good (but it is quiet). If yo u build your Rickman and don't do something with the pipe yo u won', notice enough top en d hor sepo wer to make it wo rthwhile, but . you will inc rease your bottom end torq ue a bunch. Yo u can always get your high pipe modified later, or ge t a - low reed pipe if you want t he m axim um that the engine can give you. Reed porting: follow the steps in Diagram No .3 and yo u won't be very far off for MX or TT racing. For Enduro or woods riding leave the ports as they are, and install the reed as per Diagrams No: 3 and No.4, Diagram No .5 is for MX. Don't use finger ports, and by all means don't let the tip of the ring run in t o a reed port o r it. will be sleeve time fo r you. Modified reed cage and stops, worth an other six to eig ht tenths of a horsepower, cost $10.95 . Now I know you have been loo kin g at the dyno chart and wondering ho w in the wo rld did I get 23 .0 p lus horsepower. I can get m o re now because this power cu rve was plotted almost a year ago. September 19, 1973 , and now I'm pu shing 26 .0 HP. To get thi s kind of reading you're looking at a works engine with a special sleeve, .080 maximum legal ove r-bore and everything' possible done to the inside of t he engine: b lueprinted. mainshaft a nd rod shot-pee ne d, balanced, E.C. b utton mag. It costs, rounded off, abo u t $28 per h orse. A lo t of today's engi nes are capable of 20 .0 HP at the rear wheel wi th so me work done to them . Zundapp . Sachs. Hodaka, Ho nda. Suzuki, and Yamaha (to name a few). all have one co m m o n' problem, th at 's the lower rod bearing . The factory hea ri ng just can' t stand the load s a racing top end can put on it. I' ve been using a special lower end rod bearing in a very extensive test for the past t wo years. It is made by hand o ut of a special space age ni ckle bas e alloy. The ro llers are of a special grind that makes them a hai r sm aller o n the end, which keeps them from scooti ng. This heari ng was bu ilt by Mr . Bob Burris for cart engi nes. and I've no w made it usab le fo r motorcycle bottom end rod bearings. This E.C . bearing costs $14.50 and comes wi th , ins tallation instructions. So me engines ha ve to have machining do ne to t he crank wheels a nd pis ton to use this hearing. If you want to take t he easy wa y out , send us yo ur cr ank asse m bly an d pi st on and we will do a ll the machining and ins ta ll the bearing fo r yo u . In'st allat io n cos ts from $50 to $75 dependi ng o n the crank . Is it wo rt h it? Well. it's up to you. I've ha d t hese hearings go for mo re than a year and a half in a racin g engine wit ho u t failing. In fac t. I' ve never had a p ro b lem wit h one o f th em . At the p resen t we have t his hea ring in one size o n ly. which fits m ost all engines . T his bearing will wor k with any rod with a 24m m eye and a crank pin of 18mm. T he 125cc to 150cc sleeve kit is th e same liner fo r these sizes. T he plus .080 over piston is a special, pis to n I have made fo r m e by Ve nolia. It's a forged piston and co mes with an unbrea kable dyke rin g. You can 't b uy it from Venolia because it's a special design of my own. Piston wit h ring, spacers, and pin (if need ed ) is $36.95. T he 150cc engine size is the biggest yo u can make your engi ne wi thou t machining your cases or using a special liner. There is another kit o n th e m ar ket and the last one I saw was all wrong. If yo u try and use one of th ese , yo u're in for t rou ble, If yo u have bo ug ht o ne of them and wasted yo ur cylinder, m a yb e we can save it. The, biggest that yo u can Piston reed ports MX & enduro .60 0 bu ild yo ur Zundapp withou t a ton of money is 160cc. T his takes a sleeve 0.0. of 2.850 and a pisto n that is 62 mm bor e size. Is it wort h the ex tra cost? No, I d o n't think so . The 150 cc will p u ll li ke a 450cc Maico on th e bo tto m end a nd blo w 99% o f th e 250s in the weeds . The Zundapp has ano ther engin e for yo ur bike . Ric kma n chose it fo r their bike an d they don't do th in gs hal f way. Tom Baug h p u t a. Zundapp in h is Penton because h e li ked it be tter th an the Sach s engine it came with p lu s the Zundapp e ngine is seven po un ds ligh ter than t he Sachs engine. T he Pendapp weighs in at 1 76 poun ds with gas. T o m is a CMC Pro r ider and win n ing races is the way he m a kes his living. Ho pe I 've shed so me Iigh t on th e Zundapp for you . If I'v e left o ut anyt hi ng Y0U need to kno w, give m e a call o r drop a letter off to "Ask E.C . ", Cycle Ne ws Wes t. East o r Cen tral. Is a Zundapp for yo u? On ly you can answer th at question . b u t you could d o . m uch wo rse . Fo r m y m oney I fee l the Zundapp is one hell of a bike . •