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/126338
;; • s t lIS -; 00 r--. (j) ~ ~ 1-0 q; ..c S q; ;> 0 z Remote reservoir Ohlins shocks come on the production version. I I I The forks feel like big fluffy pillows without the bulk. ' 11 \ 1 Trans-AMA Bike Impressions: Chuck Sun's 1979 Husqvarna 390 CR By J im Gianatsis Photos by Chuck Tannlund an d Gianat sis Over the course of the next eight weeks or so we will have the rare, if not exclusive privilege of providing you with direct technical and riding impressions of the major factory bikes entered in the 1978 Trans-AMA S ries.The purpose of these e . . ~epons will be to. give. you an Idea of the englneenng ad- 1 0 vancements taking place in motocross, and how these exotic works machines relate to their production counterparts of the present and near 'future. If along the way we draw a few comparisons between the different works bikes , then things will be all the more interesting. . T~e first bike to fall u?der our scruuny was , Chuck Sun s ~90~c H~sqvama, prepared by tuner Er ic C~ppa ". Husky has a much closer re o latlo?shlp between proto~ype and pro· duction t~an th~ major Japan~e ' tea,;!s, so II wa~ with no ,rea l. su~pnse we ound out t at Chuck s bl~e IS actually the new 1~79 pro?uctlon C.R, due ~o ~e ~vaI1able In America som~tlme . In ovember. Only ~ few modlfica.tlons were ":ad~ t.o the bike to prepare II f?~ Ch.uck s riding sty~e a~d the compennon It ,:"ould be facing In the Trans·AMA Series, The engine remains nearly jdenrical to the present 1978 bikes. its ~90cc dis pl~ce~ent being fed by a. ~8mm Mikuni through two pyramid reed blocks of four petals each , The transmission ratios are shuffled around a little. though. to take better advantage of the ~90's broad powerband. Wide ratios replace first through fourth gears. while close - ratio gear sets remain in fifth and sixth. The result is the off road gearbox ratios already in use with the OR model Huskys. This change should give the 1979 ~90 CR more versatility as a dual -purpose bike for motocross and cross country racing. But the wider tranny ratios also make the ~90CR a faster , easier bike, to ride since less shifting will be required in the lower gears, allowing the rider to take full advantage of the broad. tractable powerband that pulls readily from 2.000 rpm . Crippa admitted to having done a little work to the stock CR cylinder (porting), though most of ,this was just normal cleaning and matching of the alumi num cylinder to the steel liner. which helps to improve torque throughout the rev range. What's really new on the 1979 model is the chassis. which we saw in prototype form ridden by Hakan Carlqvist in last year's Trans-AMA , Series. The frame is all-new to incorporate geometry and design changes needed for longer travel suspension. Also it was changed to house the new airbox design in a more conventional location, inside the frame behind the engine. replacing the side-mounted magnesium airbox used previously. The side of the new plastic airbox swings open to allow easier access to the foam type filter . Suspension changes also help put the production Husky back on par with all the other works bikes. Front forks are Husqvarna leading axle air/spring units with 11.8 inches of travel. The rear has a matching amount of travel , controlled on Chuck's bike by experimental Ohlins DeCarbon type shocks which have their reservoirs fixed to the shock body like the Showa shocks that come on the RC Hondas . Attaching the reservoirs to the shock body probably provides a lit tle, smoother dampening control , but more important Iy is lighter. less bulky, and more reliable than remote reservoir shocks. Production Huskys will continue to come with the present remote reservoir Ohlins for at least this year. with the fixed reservoir Ohlins expected to be phased in sometime in 1979 . Something really interesting about the shocks on Sun's bike were the springs. They included the normal soft initial spring. but the straight wou nd hard spring was replaced by a Etogressively wound hard spring. Cripi'a didn't know what the specific spring rates were since Ohlins just provides him with a selection of different color coded springs. and _ when Chuck doesn't like one color. they try another. The only major modification to ,th e bike was a one inch lengthening of the sw-ingarm just behind the swingarm pivot. This in tum required the prototype shocks to be a little longer fh'I m the stock 16.25 inch Ohlins which come with the bike - otherwise, a littl e rear wheel travel might be lost. This increases' the wheelbase on the bike to 57 ·58 inches depending upon chain adjustment. Such a modification might slow up handling in tight turns. but Sun is a pretty light rider, and needs the longer wheelbase to keep'the front of the bike down and tracking straight under hard acceleration . •.) (1) Complete. ready to ride weigh t on Chuck's Husky was 229 pounds , making it just in the ballpark wlfen compared to the weights of the othtr. more exotic. factory Open class bikes . But it is a good deal lighter than other Open class production bikes. with the exception of Maico. But the difference in weight is made up for by the i dditional inch of suspension travel ' the Husky hi'S over the Maico . 11 How competitive the new Husky will be was demonstrated by Sun in "the opening moto at Mid-Ohio's Trans AMA. In his first race on the new pro' duction bike (only his second 500cc