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Fantic 340

Not to be confused with the 340 Bultaco, the 340 Fantic is a hybrid twinshock machine, which is far better suited to modern conditions than original twinshock machines, and is built using a 240 chassis, and 300 motor (249cc). A properly built 340 is highly competitive, and doesn't need to cost the ridiculous sums of money that are often being asked for much less effective machinery at the moment.


With sound twinshock machines becoming increasingly difficult to find, and prices asked for popular or collector's bikes sometimes being more than that of a brand new modern bike, building a 340 Fantic makes a lot of sense. The 249cc motor was first used in the 300 Professional, and in piston port form with minor detail changes, was also used in the earlier monoshock bikes introduced after production of the 300 Professional ceased, so is still relatively easy to find for reasonable money.  


The fact that the earlier monoshock machines used a power unit that is effectively identical to that used in the twinshock bikes, means there is a ready supply of inexpensive donor bikes that can very often provide nearly everything other than a chassis required for a 340, means that costs are much reduced, and anyone can build a bike to suit their own requirements exactly. Only problem area here being that ACU rules forbid disc brakes in national twinshock events, so anyone wanting to take part in these trials on a 340, will need to fit drum brakes to their bike.

ClassicTrial 340 Fantic twin shock project

Very minor modifications to the 240 right hand lower frame rail, to allow later larger diameter flywheel housing of the monoshock motors to clear the frame tube are needed, and ideally a cylinder head steady of some kind is required  which can be made from scratch or adapted from parts intended for 249cc bikes. However engine performance will be poor if OE 240 exhausts and air boxes are retained, but parts from the 300 Professional can be easily adapted to work properly, but are not that easy to find. Steering geometry changes and alterations to footrest position also make a lot of sense, and in combination with Falcon rear shocks, and properly set up forks, will improve handling very noticeably.


Perhaps the ultimate 340 is one fitted with one of the very last of the reed valve induction air-cooled motors, that is more powerful and tractable than the earlier piston port motors, but bearing in mind that these do require very careful attention to intake and exhaust systems to work properly, and using OE 240 parts will result in something that's not particularly nice to ride, and has quite a narrow power-band. The other problem with the reed valve motors is that the design of the pistons means that motors are often very noisy after any amount of use, and damage can ensue if this is not rectified properly. We have looked at this problem very carefully and can provide special updated forged pistons, specifically designed for the reed valve motors, which increase power, and greatly reduce the chances of a rattling and sick motor.


Finally we would be pleased to provide advice regarding 340 builds, but cannot help with conversion work ourselves, and once more would remind anyone wanting to do a 340, that air-box and exhaust are extremely important, and its not just a matter of carrying out some simple chassis mods and bolting in a bigger motor. Please email classictrial@gmail.com if you need any advice on your 340 project.


* Finally please remember that all of the above information is provided on the strict proviso that any modifications or changes not carried out specifically by Classictrial, are not guaranteed or warranted in any way, and are entirely the responsibility of the individual carrying them out, and that Classictrial are not responsible in any circumstances for  damage or injury, that may occur as a result of poor workmanship. *

Classictrial prepared 340 Fantic

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ClassicTrial prepared 340 Fantic twin shock See also Fantic what’s new

Classictrial 340 Fantic build

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