WillBrown Internet -
In general Fantic’s are perhaps the most reliable of all the twinshock machines, but a fault that is quite common, is breakdown of the ignition source coils insulation. This is something that very often causes a bike suffering from bad insulation, to stop running when it gets hot, but to start and run fine after it has cooled down fully.
The bikes this fault affects most commonly are early twinshock models fitted with the “Dansi” ignition system, which is easily identified through the fact it has an external ignition pickup, that is activated by a trigger on the outside of the flywheel.
Luckily this is an issue that’s very easily rectified, and simply entails removing the flywheel, and replacing the faulty coil, with one that has been rewound using modern epoxy insulation, which is far more durable than what was used on the original coil, which will mean the problem is not likely to occur again in future.
There is a specific resistance value for the source coil, but relying on this to determine whether or not your coil is faulty, is not a particularly good idea, as it is common for the resistance to vary with heat, and a coil may well check out fine when its at room temperature, but will fail when its fitted to a bike, and obviously has to contend with much more heat/load.
We would recommend a careful check of the ignition system wiring initially, with particular attention being paid to wiring related to the stator (pictured), which will require removal of the flywheel and the stator plate itself (remember to mark it before removing). The HT lead and plug cap must also be carefully inspected, and an NGK silicone rubber competition plug cap without any sort of internal radio suppression resistor, is always a very good idea.
If all of the wiring checks out OK, then its pretty likely that the source coil will be the cause of ignition failure, and we would suggest contacting someone who can help with supplying a rewound coil on an exchange basis, and check the resistance of your coil with the figure the supplier of rewound coils will be able to provide (Fantic spares suppliers can be found on our links page). However its worth bearing in mind the fact that resistance values can and do vary with heat/electrical load.
On Dansi equipped bikes which have not already had the original cylindrical alloy
Finally its worth making sure that ignition covers are properly waterproofed, as water in the side case, is the main reason the OE coils fail, and this problem is something that can be avoided if the side cover can be kept free of water.
Fantic Dansi stator (source coil on right)
Click to enlarge
Fantic ignition fault
* 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 *