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by Svend-Erik Neilsen

When Emil Jern, from Gävle, Sweden had a very early motorbike, he decided to manufacture a cheap alternative: a clip-on engine for a bicycle.  He finished his first engine in 1915 and he named it "Furir".  It was a single cylinder four-stroke that developed 1.5hp and mounted over the front wheel of a bicycle.

The wheel was driven directly with neither gearbox nor clutch; both primary and final drives were by exposed chains.  The ignition system was a German UH magneto and the home-made carburettor was of the Amac type.  The engine was fastened to a sub-frame that attached to the front wheel spindle at the bottom, and clamped to the handlebar stem at the top.  Adjustment was provided to suit different sizes of bicycle.  The construction rights were sold to two people from Gävle who built a factory, "Motorfabriken Furir", to make the engine units.

In 1917 they also started building a stationary engine for driving water pumps.  The cyclemotor engine was improved in 1918, with a Bosch B1 magneto, an improved carburettor, a new stronger 3-litre fuel tank and a stronger driving chain.  The sub-frame of these later units was modified to incorporate leading links.

The crankcase on the original model was cast in aluminium but, after problems with cracking, it was decided to produce them in cast iron.

A larger sprocket could be fitted to the front wheel when lower gearing was required for driving heavier machines such as delivery tricycles.

The company was renamed "AB Motorindustri" in 1919 and the name of their engine was changed to "Colibri".  The water pump engine and an engine for powering boats were also being produced.  12th July 1919 saw production moved to Nordiska Aviatik in Tellusborg near Stockholm and the company became "AB Colibrimotorer, Liljeholmen".

The bicycle was somewhat top-heavy to ride with the engine mounted over the front wheel and, despite the leading link forks, the engine itself was unsprung so that chain adjustment would be maintained.  To overcome this problem a new version of the engine was produced in 1920.  This fitted in the triangle of the cycle frame and drove the rear wheel by chain.  To allow for independent adjustment of the pedalling and engine chains, an idler sprocket was clamped to the cycle's chain stay just behind the bottom bracket.  The 3¼-litre fuel tank was round but with a groove in the top where it fitted to the cycle's top tube.  Modified pedal cranks were needed to clear the sides of the engine unit.  A full tank would provide sufficient fuel for 100km to 130km and the complete unit weighed 16kg.  The frame-mounted engine also had the leading link front fork.  The new Colibri motor cost Kr175 but the front wheel drive version remained available at a slightly cheaper price of Kr150.

A 250cc V-twin motor cycle was also produced from 1921.

The Colibri cyclemotor sold well and was the first clip-on engine to be manufactured on a large scale in Sweden but, despite this, the company went bankrupt in 1923.

Engine type 4-stroke AIV
Bore/stroke 52.5mm × 58mm
Volume 123cc
Magneto Bosch B1
Lubrication Automatic (no oil pump but regulated by a valve under the oil tank)
Carburettor "Colibri" patent
Transmission Chain
Tank capacity 2 litres petrol, 1 litre oil
Weight 16.5kg
Speed 30 to 40 km/h

First published - December 1992
Added to archive - 30 April 1999

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