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Upcoming Trail Ride Event

Apr 4 2022 - 15:00
Llandovery (SA20 0NB Wales)
Llanerchindda Farm, Cynghordy

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    Sleekest, prettiest bike of the end of 70’s

      250 RS GS1978/79

The SWM 250 GS is a strikingly beautiful red, white and black machine; but there is more to the SWM than good looks!

 Its main purpose is to win ISDT type events. A good ISDT machine needs a strong flex-free frame, powerful engine with a transmission that furnishes one mph in low and 80 mph in sixth, quiet exhaust, strong and waterproof brakes, enduro lighting, large unbreakable fenders, centre-stand, good suspension, nimble handling and a heart made from Kryptonite to endure the torture of six-day competition.

Not many bikes can claim all these features in stock form. The SWM 250 GS can. Completely stock it will out perform the abilities of all but a handful of professional riders.

SWM makes its own frame, pipe, seat and tank. Other parts are supplied from Bing, Marzocchi and Bosch. The engine comes from Rotax, an engine builder in Austria . It has generous finning on the cylinder and tons of horsepower. Bore measures 74.4mm, stroke is 57.5mm for a total of 247cc. A 32mm Bing center float carburetor sits behind the cylinder and feeds fuel through a long intake tube to a left side rotary valve that opens a port into the engine’s lower end. An electronic Bosch ignition furnishes spark for the plug and juice for the lights and feeble horn. The transmission has six widely spaced speeds and a gear is available for almost any situation. The counter-shaft sprocket is placed to the rear and the frame is constructed so the swing arm pivot rests as close to the sprocket as possible. A good case guard surrounds the front of the sprocket and prevents damage to the magnesium castings if the chain does happen to derail at the rear. The shift lever has a spring loaded end to prevent internal transmission damage if the rider jams it into a rock or tree root and primary starting is used, an appreciated extra when stalled on a muddy hill or creek bottom. Restarting is as simple as pulling the clutch and stabbing the left side kick start lever. A die-stamped snake pipe, made by SWM, is used on the GS. It manages to pull even more horsepower from the strong Rotax engine than Can-Am gets, but at a loss of low-end power. The large silencer effectively silences the two-stroke crackle but isn’t forest legal as it doesn’t contain a spark arrester. Pipe and silencer are securely mounted and vibration is isolated by rubber blocks.

The frame on the GS looks as if it was built in a custom frame shop. The steering head is set at 29° and rotates in tapered roller bearings. A large single front downtube leaves the steering head then splits into two smaller ones just above the exhaust port. The smaller tubes curl under the engine cases and terminate at the swing arm pivot. Cross bracing is employed in several places below the exhaust port, adding strength and furnishing protection for the engine cases. A big backbone tube is used but ends at the tank’s rear, where two small diameter pipes weld to it after starting at the lower part of the steering head, heading rearward to the backbone’s end then curving down, ending at the swing arm pivot.


Seat rails and sub frame tubes are equally sized and three triangles are formed from straight pipes in the area under the seat. Frame flex? No way, not with a frame like this. A straight tube swing arm pivots in tapered roller bearings and uses double cross tube bracing at its front. An excellent centre-stand is furnished. It is made from small tubing and folds to a position that acts like an extension of the frame’s lower part, a position that lets the machine slide over fallen trees without hanging up. The frame, swing arm and center stand are made from chrome-moly tubing, nicely welded and expertly painted red.

Marzocchi leading-axle forks are used. They are the 10 in. travel models with 35mm stanchion tubes. Action and control from them is good until a square hole or sharp ledge is hit, then they jar the rider. Enlarging the compression damping hole slightly makes them almost perfect though. Wonder when the Marzocchi factory is going to start doing this for us? Laydown number 4 Marzocchi reservoir shocks are stock on the rear of the GS. They offer an air valve for controlling internal pressure and can be adjusted internally by changing the valving. Once broken in, they smooth out bumps and holes without kicking the back of the bike or jarring the rider. High speed users will have to fool with different damping valves and pressures.

Sachs conical hubs are employed front and rear, laced to Akront aluminum rims. Spokes aren’t exceptionally large but only loosened once during several all-day outings and none of them broke. Tires are Italian-made Pirellis and don’t match the high standards of the rest of the machine. They skate in corners and offer poor traction when braking or starting. After our first day of riding, the SWM rep replaced them with Metzelers and the front wheel skate and traction problems vanished. Tires that are less than first rate shouldn’t be standard on a $2100-plus motorcycle. Nice nylon fenders are used on the GS. They are wide, long, and do the job they are supposed to do—keep mud and water off the operator. The rear has a straight, flat section between the seat and rear frame loop. This and two frame tabs either side of it provide a place for carrying an inner tube or spare parts, a necessity in six-day competition. Slightly rear-set side number plates are also made from tough nylon. Vent slots are punched into the front of each and allow cool air passage for the shocks. The choke lever on the rear-set Bing carburetor is reached through the lowest one on the left side. A combination number plate, headlight housing and speedometer guard is held to the forks by stout rubber straps. A very good nylon airbox is used on the SWM. It has a removable top that keeps water out but lets the owner in for maintenance. The carburetor and engine vent hoses are also routed into this box so fording deep creeks won’t pose a problem.

The SWM has a rather short, rounded seat. Its shortness is intentional; more room is provided for carrying parts on the rear fender. Foam firmness, width and thickness are perfect. The tank is a shape that seems strange to us hut blends nicely into the seat and is mounted low on the frame. Made from steel, the tank only holds 8 litres of premix.

Serious European enduro riders have furnished much input on the SWM. Best of all, the factory has listened. Both brake arms have return springs so even the muddiest conditions won’t cause them to stick.

Probably the most overlooked feature on an enduro machine, and one of the most important to the serious enthusiast, is utilizing as few bolt head sizes as possible, thus reducing the amount of heavy tools he or the hike will have to carry. The GS has had special attention directed toward combining bolt head sizes. Bolts that screw into a tapped hole use 13mm heads; if a loose nut is used the nut is self-locking with a 13mm head and the bolt has a 6mm Allen head. The machine can be almost completely stripped with the following tools: 5mm Allen wrench, 6mm Allen, 13mm end wrench. 10mm end wrench, flat blade screwdriver, and a straight bar to turn the rear axle nuts. Removals of engine side covers, shift lever and kick starter require only one small tool—a 5mm Allen wrench. 

Starting the SWM is almost always a one kick procedure, hot or cold. The kick lever is left-side mounted but doesn’t seem clumsy. It is easily reached without stretching, completely clears the footpeg and spins the engine with minimum effort.

First time SWM riders should he cautioned about the high bhp engine and light front end characteristics. Rapid acceleration in a sit-up position will result in instant wheelies through fourth gear and the machine is very easy to loop if the rider doesn’t lean over the handlebars.

Clutch pull is heavy, but the clutch completely disengages once in. Shifting is stiff and requires the use of the hard pulling clutch when shifted fast, otherwise it will balk and refuse to move. Handling is quick and positive, almost too quick for all but expert level riders. Bars are overly wide and contribute to the machine’s sensitivity to rider input. We trimmed about an inch from each end. Both brakes are excellent and they stop the bike in a controlled and progressive manner without being overly sensitive. The powerful engine lets the SWM conquer hills without breathing hard, yet is perfectly happy at a turtle’s pace.

The SWM 250 GS is aimed at the serious enduro rider and beginner/novice riders will find the bike too much of a good thing. Its ultra quick handling, explosive power and light front end could spell danger for a rider who hasn’t yet developed the quickness and skill the SWM demands. But an ‘A’ or ‘B’ rated guy on the GS could very well fill his trophy shelf with first place gold.


                                                                            Moto Cycle World mid 1979.