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/126816
1985 GM250 M-star: A star is born By Kit Palmer M-Star might not be a household word, but the new 1985 GM250 from the small West German factory is out to change all that. Although last year's SC250 debuted a single shock rear suspension system · · I n an d water-coo 1lng, II didn ' t make much of a dent against the better-suspended and more- 10 powerful 250cc motocrossers from Japan. The 1984 SC was heavy -:' 20 pounds more than the CR250 Honda - and the brakes didn 't cut it ; excluding those shortcomings, the SC handled de cently, put out moderate horsepower and was fun to ride. But as a full-fledged racer, the M-Star wasn't a threat. Soon after the rel ease of the SC250, M-Star engineers went to work and came up with the GM250; not much was left untouched - the frame, suspension, brakes, fuel tank and engine were a ll chan ged for 1985. Last yea r's M-Star 250 had a very prpey motor - decent power midrange and on top, but lacking power o ff the bottom. This year, a new exhaust pipe and paning are in corporated to aid low end. The rest of the water-cooled, reed-valve, two-stroke engine remains unchanged ; bore a nd stro ke arc 67 x 70mm, actual di splacement is 247cc. Like last yea r, th e M-Star has two radiators mounted forward o f t he ga s tank, a nd the water pump is con nected 10 th e left of th e cra n ksha ft. • Th e M..5tur's .oIUich assem blvr isi on : th e left, a n d th e ch a in d rive is on th e I right, o p p osite Japanese moiocrossersThe exhaust pipe runs from the . c~nter-l?on cylinder, winds up t~e right side of the frame a nd exits through a rebuildable aluminum silencer. The pipe is hand-made and comes unpainted for th e " wo rks" look. Carburation is h andled by an aluminum-bodv , round-slide 38m m Bing, with a choke pull knob and a tickle push button . The airbox is plastic, carrying dual-stage oiledfoam air filt ers , access to the filter is from th e top, after removing th e seat. The M-Star has a five-speed tr ansmission and a wet multi-disc clutch, same as last year. The clutch still has a very hard pull and a quick, springy return actio n , while th e shift lever is made out of steel and has a folding tip with a rubber pad. The kickstarter lever is also made of steel and has a rubber boot pad -the unit is mounted on the left side of the bike, a nd is a very old design; most Japanese bikes in the mid- 70s had th e same type . The 250 uses a Mor oplat transistorized ignition system , and the magn eto ass embly is g ua rded by a red , pl astic cover held o n by four flathead scr ews. Protecting th e magneto from a derail ed chai n is a sturdy ca se sa ver. but there is n o co ver o ver th e co untershaft sproc ke t; the drive cha in , is u. gold-annodized pl2QRegina . j." T he do uble-cradle chro me-moly- , steel frame is made lighter this year by increasing the diameter of 'th e tu bes and decreasing the thickness of the walls. The steering head is slightly lower this year and the wheelbase is one inch shorter at 58 inches; replacing last year's swingarm isan all-new box section aluminum swingarm that is considerably lighter. The seat height has been lowered by one inch, to 37.5 M-Star called its 1984 single-shock rear suspension system the Twin Link; after major linkage changes, it is nowcalled the Twin Link 2. The linkage has been completely redesigned for a more progressive damping curve, and the Ohlins shock with a remote reservoir used last year was replaced by an Ohlins piggybackreservoirshock with separate, external rebound and compression damping adjustments. The rebound knob is lo cated on the reservoir and has easy access, while the compression damping adjuster is found at the bottom of the shock strut and is difficult to get to. The linkages and levers pivot on new teflon busings (there are three pivot points), and there is one grease lubricating (zerk) fitting. Total wheel travel is a long 13.5 inches. The air-adj ustable telescopic fork is made by M-Star; it's lighter for 1985 and now has teflon guide bushes on the damping tubes. Wheel travel is 12 inches. New th is yea r is a hydraulic front disc brake, which is a good thing last year 's drum front brake was next to usel ess. The 1985 front axle is larger in diameter to increase rigidity of the fork, and both front and rear hubs arc made out of a lighter alumi num material (th e rear hub is conica l) . M-Star hasn't yet developed a straight-pull spoke set-up that the Japanese bikes have had for the past few yea rs. Rims are made by Nordisk and a re co ns tructed of aluminum; tir es a re Perfectcross Metezlers. T he rear br ake assem blv is mounted o n th e right side; the same side as is I' th e.rea r sprockotxaccording ( tl aruM» Star spo kesma n, th is will no longer be the case next year) stopping power is handled by a single-leading-shoe system, and the brake arm is mounted to the chain guide. Between the rear 'bra ke actuating arm and the rear brake pedal is a steel rod that pivots on parallel to the swingarm axle. creating a floating effect. The rear brake can be adjusted by hand. twisting a wing nut on the end of the rod. Cosmetically. the M-Star's radiator shrouds are reshaped, as are the fenders and side panels; the seat is now blue instead of black and the gas tank holds half-a-gallon more (2.8 gal.) this year because the left side of the tank is dropped down six inches. This also lowers the center of gravity to aid handling. The controls on the handlebars are made by Magura , and include the levers, whirlpool throttle housing and the front disc brake's master cyclinder. Footpegs are cleated, but the rear brake pedal is not. Claimed dry weight is 216 pounds (16 pounds lighter than in 1984), making the MStar still one of the heaviest in the 250cc class. Rid ing Before we even got the chance to ride the M-Star. we came across one thing we disliked - the kickstarter. For right-handed riders, a kickstarter on the left side is difficult to use; but even for a left-handed rider, using the kickstarter on the M-Star is a pain. The lever itself is a little too tall, and it folds up when under the footpeg at the bottom of its stroke. This causes the rider's foot to continue all the wa y to the ground, non -stop, while the lever flies back up to its origina l position . It is a terrible nuisance, and it happens every time the rider takes a stab at the kickstarter. Fortunately, M-Star fires easil y. Trying to stan the GM while sitting on the bike is no fun at all, either. Besides that , if the folding kickstarter doesn't cause the rider problems then the litt le rubber pad on the lever does it - slides off the lever after a few ki cks a nd lets your boot slip off. The "p ro ble m . is . worse. UIlder. wet co nd i tio ns .