SWM 280 Mono

My father always wanted to make my SWM 350 Jumbo into a monoshock, but strugled with the centre carb and suspension , plus I rather liked the bike  and didnt want it hacking to bits !


I saw this  picture some 25 years later and just thought wow it was possible afterall !


I then saw another bike , it looked like an SWM to me but with a Moto Villa engine , what was this SVM ?


SWM  to me had to have a Rotax engine  and so the next project began ......



SWM 350 Mono


Aprilia TX 311

Armstrong Mono Prototype

Aprilia TXR 312M

Armstrong TA 280 Mono

The above bikes  with rotax engines inspired me  and I decided to go for a 280 engine and use an Aprilia frame set up, exhaust front pipe and cylinder head.  whilst the Armstrong was similar even with its SWM rear silencer, I wasnt sure about the alloy front section of frame. I still had no idea what engine, suspension or brakes to look out for?  So the search began ..........

Should I buy a complete bike or parts , well  at the time not many bikes about so I ended up with a load of bits above from an Aprilia TX311 rear drum brake  version.

Wanted to see what the tank would sit like , so in with the air box and built up the rear subframe,  alot of  head scratching and looking at this point , biggest area to modify would be the whole of the rear subframe so the seatbase would sit flat on the frame.

Next step was to try an engine and wheels to see how things looked, straight away it was  going to need the steering stops on the frame moving if I was to use betor yokes, the Tank is sat on the frame but is not level with the front pipe, then what about the fuel tap! 

Look at the rear frame and mudguard mounts  all sat far too high! 

So out with a tape measure and  took some rough measurments  from the 350 Jumbo, It confirmed my earlier thoughts the rear frame needed to be altered. Not going to be just as easy as I would have liked........

​Basically a complete new top section of the rear subframe including filler panels and seat base mountings. 

Okay so starting to feel really good about how things are going but my 320 Jumbo needed its engine back, at least everything now fits and looks right especially the exhaust front pipe, still have a major worry over the fuel tap.......

Front tank mounts made and a coat of paint starting to take shape, came across  an Aprilia TXR 312M rear shock, so a quick mod to the front frame and job done.

Look closley at the clutch cover, no water pump just a cover, interesting could I get an Aprilia Climber and turn it into an air cooled?

I was going to buy the Aprilia TXR 312M   for the clutch cover and then all the parts, not that many about , one in italy for 1400 Euro that was in very good condition?  So what about going totaly the oposite and get a climber for the electronic ignition, hydraulic clutch  and so on?

A 1994 Aprilia Climber like the one above  came up for sale about an hour away  game on lets do it !

A bit damp in the worshop but as you can see air cooled barell and head fitted, hydraulic clutch  and rear brake resovoir added to frame

decided to go with a stainless steel sprocket  cover rather than the Climber plastic one, used the TX bash plate a bit of rear shaping and fits spot on

The finished product with Aprilia TXR 312 M  forks and yokes , Climber wheels  , front wheel has different internals  and bearings to take the smaller diameter front spindle  for the forks.  The fuel tap was off the Climber fitted a treat ......  the bike actualy rides really nice just need to ride a trial on it now !

The bike  was  simply built as a tribute to my father and  Pietro Sironi with the intention to ride in modern trials  against modern bikes !


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