Cycle News

Boy. is Leo Payne going to be surprisep., CXl w Z U .., ~ > :; W ..J U >- , By Keith Arnold A650cc Yamaha Two-Stroke Automatic . For several years now Yamaha International has had a 650cc two-stroke tWin. The main problem in relation to motorcycles has been the fact that the motor is for snowmobiles. Until this changes, the only people to possess this workhorse will be those willing to adapt this mactiine to a motorcycle. To say that this machine is unusual would be understating the case. There is no clutch or transmission nor is there any need for one. Word has it that this motor is in a motocross frame but no one seems to have seen it. The one that many have seen is Gary Bowers' super Quick drag bike. This kind of machine could be the bike to beat as it has already far surpassed all national records for its class. . This is the little goody that makes the whole thing work. Doesn't look like a big thing, doesn't feel like it would do much. However, what you are looking at is the clutch. Or at least the thing that makes the torque converter work. This v~belt, moving between two sets of expanding or contracting discs, is the transmission and the clutch all in one. Under force the front set of discs expands while the forward set contracts. What this does is effectively increase the overall "gear" ratio from essentially nothing to one ratio to a final 1: 1 at top speed. This eliminates the need for the standard trans and clutch assembly. This saves many pounds. While this may handle the gearbox chore, there is still the need for a countershaft and rear sprocket. The main difference is that the countershaft is really a jackshaft, one end of which holds the one half of the torque converter and the other holds a sprocket. " • • • - Withoul Ihe rider, Roger Cavis, Ihe enlire bike weighs just 186 Ibs. This is Ihe whole Ihing. The frame is a s~per light chrome moly skeleton. The weight with a rider is hard to believe, just over 350 pounds. According to the Lions Technical Inspector, this is the lightest 650cc motorcycle ever ridden at the strip. The power to weight ratio is 3.6 to one. The frame, made by Schwerma, only weighs eight pounds. This plus wheels and components gives a dry weight of 93 pounds. What you can see here is the rear disc brake by Kelsey Hayes. The tire 'is an M&H bike slick. The large vaned aluminum round goody is one half of the torque converter. The small drill holes a're for balancing. In this shot you can see the footpegs. Notice that there is nothing for the feet to do but hold on, The brakes and all other controls are either up front or just not there at all. Still not convinced? Read on. It you follow the racing scene, you know the all new '72% Puch is a real winner. For those 01 you who don't: On February 20, 1972 Jeff Wrigtlt became the first but one of Saturday's 1.000 entrants, for second overall willner. Sunday, Jack Morgan, on a 175cc Puch, won overall in the 250cc Open Expert Class. Currently Bill Friant is leading the AMA 37th District Division 2 lightweight class on a 175cc Puch. If you're still not convinced. come into yOuf nearest Puch dealer and see one. Seeing is Believing. PUCH DISTRIBUTING 9825 MASON AVENUE CHATSWORTH. CALIFORNIA 91311 PHONE: (213) 882-8272 This is the whole motor. The heads are of the hemi variety with slighty domed pistons. The size of thiS motor is only 643cc yet it produces in excess of 100 horsepower. Within the starter housing is the electrical system and flywheel. The basic motor components are very simple. On top are the heads and barrels; the upper case comes next and with its partner. They house the crank. Stick in some huge pistons and there is a big two stroke. Your Official Western States Puch Dis!. person in California history to win a desert hare and hound race overall aboard a 175cc machine. APuch of course. Jeff has been putting it on Ihem at Ascot Park's nighl MX series, too. To date Jeff has put logether an unbroken string of 6 wins, Luck you sa't? Read on. At Ihe annual Elsinore Grand Prix this year, Jeff beat all

• Cover