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Fantic Trials Update

* 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 warranteed 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 *

Adrian Cairns 240 Fantic

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ClassicTrial picture, Adrian Cairns 240 Fantic, click to enlarge click pop-up to close.
Over the last few years, higher level twin-shock trials events here in the UK have been largely dominated by modified Fantic machinery, and these bikes remain the best possible choice for anyone interested in serious twin-shock trials competition.

One of the main reasons the Fantic works so much better, is simply down to the fact that it is the only twin-shock machine with a power unit purpose designed for trials use. The format of powerful, light, compact, high revving motors, with gearbox sprocket close to swinging arm pivot having been successfully adopted on all modern machines!

Machines using motors derived from road going designs, are at a great disadvantage, as the gearbox sprocket is generally a long way from the swinging arm pivot axis (which compromises rear suspension action and reduces grip) and the sheer physical bulk of the road based motors means its very difficult to build a frame with appropriate steering and suspension geometry.

However while Fantic machinery is much more competitive than the available alternatives, there are several areas which can be greatly improved upon. The 240 in particular benefits from alterations to the steering geometry, and the fact that the standard frames distort relatively easily, tends to accentuate the already relaxed steering geometry.

Beta chain tensioner mod

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ClassicTrial picture,  Beta chain tensioner mod, click to enlarge click pop-up to close.
Main reason for the frames distorting is due to the swan-neck design of the front down tubes, with tube bends in the most highly stressed area of the frame adjacent to the steering head. To counter this problem, the factory used dual down tubes (extra tube inside outer) on the later bikes, but any frame with cracked headstock gusset plates will be distorted to some extent and have a longer than standard wheelbase.

In effect what this means is that in some extreme cases handling will be comparable to an old Spanish bike, which is obviously not ideal for modern conditions! To deal with this particular problem we are now able to incorporate additional tubes in the headstock area of the 240 chassis, which strengthen the frame considerably and help to prevent distortion in future.

Rear suspension geometry on the Fantic twin-shocks was designed at a time when tyres didn’t work particularly well, and seems to be intended to allow riders to weight the rear wheel directly for increased grip in slippery conditions. With modern tyres wheel grip isn’t that much of a problem, and alterations to the progression of the rear suspension provide better handling, and gives increased traction.

240 modified rear shock angle

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ClassicTrial picture, 240 modified rear shock angle, click to enlarge click pop-up to close.
Volume of air-boxes on stock Fantic twin-shock bikes is adequate, but performance can be improved considerably by fitting a modern flat slide carb, and larger volume air-box. On 212cc bikes fitted with 249cc motors, retention of the stock air-box and exhaust will reduce performance very noticeably, and this needs to be looked at very carefully before fitting a larger capacity motor. Modified 300 Professional front pipes work reasonably well, and can be altered to fit relatively easily.

Many people who alter the footrest position on Fantic's seem to think there is a need to move the rests back considerably. On any twin- shock machine using modern tyres this is generally a big mistake, as weight on the front wheel will be reduced, and tendency to lose control in very difficult conditions will be increased. Moving the position back very slightly, and down to the level of the bottom of bash plate is all that’s required!

Steve Martin's 340 Fantic during build

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ClassicTrial picture,  Steve Martin's 340 Fantic during build, click to enlarge click pop-up to close.
Braking on any bike with 125mm Grimeca hubs was very good when the bike was new, but many years of use will mean that hubs will almost certainly be well worn, and brake linings will only be contacting part of the drum surface. Fitting a 300 Professional brake plate with floating operating cam will improve things slightly, but the same effect can be achieved by boring the brake plate spindle hole to 16mm on a lathe, and fitting a heavy duty front brake cable. However for ultimate braking, oversize linings must be fitted, and machined to suit diameter of the hub exactly.
Front fork action on some 300 Professional's seems to be very poor, and for some reason or another the internal damping parts on affected machines seem to be very crude in comparison to other Fantic machines. The stock 35mm forks can be fitted with modern type cartridge internals, but this is quite costly, so the best option if you want to retain 35mm forks is to use those from a later orange/white mono-shock bike, which work far better.

Rear suspension action is compromised to some extent by the upright position of the rear shocks, which reduces the amount of progression and travel available. Progressive rear springs are commonly available, but these are unable to provide a linear rate of extension, so are not likely to work as well as linear springs fitted to bikes with rear suspension geometry properly designed for modern conditions (rear geometry on the TLR Honda is very good).

Performance of the ignition system of any Fantic can be improved by fitting a replacement CDI/coil unit, as the capacitor inside the CDI is something that deteriorates over a period of time, and while the bike will still run, spark intensity will be reduced, and firing point will vary slightly. This is particularly relevant to any bikes still fitted with original Dansi alloy cased round coils, which are likely to be well past their best!

Clutch lightener

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ClassicTrial picture, Clutch lightener, click to enlarge click pop-up to close.

Classictrial 300 Professional air-box

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ClassicTrial picture,  Classictrial 300 Professional air-box, click to enlarge click pop-up to close.
With regular use a Dell Orto carb is likely to be significantly worn after about a year, and even though parts are easily available, fitting these is not cost effective if carb body itself is worn. Using a more modern flat-slide carb is something that makes a very noticeable difference on nearly all trials machines, as fuel atomisation is improved, which means better throttle response and more power at most engine speeds. It is worth stating though, that improperly set up flat slide carbs while often working better than worn out OE parts, will not offer the greatest possible improvements!

We feel the best all round Fantic ever made is the 200 Professional, which is a 156cc forward kick motor fitted into a slightly altered 240 Professional chassis. However these bikes are very difficult to find, and a rear kick 200 is easier to locate and almost as good as the 200 Pro! The 240 Pro remains the most popular machine though, but it feels heavy and cumbersome in comparison to the 156cc bikes, and handling is very often impaired by distorted frames (check by measuring wheelbase).

Buying a used Fantic for anyone who is not familiar with these bikes can be very difficult, as it is only to easy to end up with a tarted up Ebay wreck, which may well cost £2k + to restore to ridable condition. However most parts are still available, and forward kick motors from later 212 and 249cc mono-shocks can be fitted to earlier twin-shock frames. However we would suggest its a very good idea to try and find a good condition ready to ride bike though, rather than buying any sort of “project” needing work!

Phil Wiffen 300 Fantic

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ClassicTrial picture,  Phil Wiffen 300 Fantic, click to enlarge click pop-up to close.
It is possible to fit the forward kick motors into the rear kick FM250 chassis, but this requires re-location of the swinging arm pivot, as well as fitting a longer swinging arm from a mono-shock machine. However for anyone with a well equipped workshop and basic metalworking skills, this isn’t a particularly difficult job, and its possible to build a highly competitive bike for very reasonable money using donor parts bought from Ebay!

Exhaust systems on Fantic twin-shocks are very often neglected, and front pipes clogged with carbon, and back boxes choked with unburned oil residues are very common. To avoid this re-occurring after pipes have been properly cleaned out, we would suggest remembering the fact that if you ride a Fantic there is no need whatsoever to use excessive amounts of inappropriate oil, which will quickly block your newly cleaned exhaust!

Kit form 340 Fantic

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ClassicTrial picture,  Kit form 340 Fantic, click to enlarge click pop-up to close.
All Fantic machines will run best on 70:1 mix, using fully synthetic 2T oil. This will mean clean trouble free running, and no need to cut open the front pipe to remove carbon, and repack back boxes on a regular basis, which is what any trials rider using castor oil at 40:1 ratio as recommended for Bultaco trials bikes, will need to do to ensure best possible performance! Contrary to popular belief using the correct amount of oil in 2T trials motors, does not accelerate wear.......... but does improve running noticeably!

Please contact us directly for more information about updates and improvements on your Fantic trials machines, or if you need help and advice about problem areas. We are always pleased to assist if we can, and its worth remembering that our advice is free, but having to contend with rebuilding/restoring Fantic machines in poor condition can be very costly!

Steve Martin's finished 340 Fantic

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ClassicTrial picture,  Steve Martin's finished 340 Fantic, click to enlarge click pop-up to close.