ianpr2 Posted May 24, 2015 Report Share Posted May 24, 2015 Hi, I recently bought a Fantic 300 ( It was my bike which I sold years back so I knew the bike reasonably well). The guy I bought it from assured me it still runs, but hadnt been started in a while. (I suspect it has been sitting in a shed for about 7 years or so). I should have insisted he started it for me.... When I tried to start it I found it had no spark. I pulled the coil off - the insulation on the earth (frame) wire was perished where it goes into the coil. I sodered a new wire on, but that was to no avail - still no spark. The coil has a Red, White and 2 Green wires and the Earth/Frame wire (1 of the Green wires runs to the kill switch) I put a meter across the wiring coming from the motor (the Red and White wires and Gnd) and kicked the motor over - I was getting some sort of voltages across them. I am at a bit of a loss where to go from here - can anyone help? What Plug should the bike use - -It had a resistor plug in it which doesnt seem correct? Thanks Ian Quote Link to comment Share on other sites More sharing options...
dadof2 Posted May 24, 2015 Report Share Posted May 24, 2015 If a wire on the outside has perished insulation its a fair bet the fine wire insulation inside the coil is on its way out as well. Borrowing a known good coil would be my first try. The output from the should be 25 V ac or more if you take the plug out of the bike and spin the engine with an electric drill, or push it swiftly in first gear. Resistor plugs are used to prevent electrical interference on TVs etc (+ other reasons) find out what you bike should have and fit that. The resistor in resistor plugs does age and wear out. 1 Quote Link to comment Share on other sites More sharing options...
ianpr2 Posted May 26, 2015 Author Report Share Posted May 26, 2015 Thanks for the help.... I will give the engine a spin with a drill and see what voltages I get - never thought of that - good idea. It is going to be a bit of a headache trying to borrow a coil locally - I live in Cape Town South Africa - I doubt if there is another 300 around here. I presume a 240 Coil will work for a test - if I can find one locally. Ian Quote Link to comment Share on other sites More sharing options...
furse Posted May 26, 2015 Report Share Posted May 26, 2015 You need to measure the resistance of the red and black wires, not the voltage you get, and dont turn engine over when you are doing this. The perished wire is common, once you get the ohms readings speak to Bill Pye, get a new CDI coil off him and if needed get stator rewound (motoplatt uk), all in will cost about £120 but the electrics will then be fine. Dont go for the cheaper flea bay versions they dont last. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted May 26, 2015 Report Share Posted May 26, 2015 You need to measure the resistance of the red and black wires, not the voltage you get, and dont turn engine over when you are doing this. The perished wire is common, once you get the ohms readings speak to Bill Pye, get a new CDI coil off him and if needed get stator rewound (motoplatt uk), all in will cost about £120 but the electrics will then be fine. Dont go for the cheaper flea bay versions they dont last. When checking ignition source coils the voltage output is a far better guide to condition than resistance. As I will explain. As a coil ages the insulation can break down and the coils start shorting together. This has the effect of lowering the resistance. As a coil ages the joints between the thin coil windings and the thicker wires breaks down gradually, this increases the resistance. One fault cancels out the other so the resistance readings stay within tolerance. When it comes to the voltage (and current) produced, both faults result in reduced voltage and reduced current so the fault is clearly measured. In general, as a coil ages the current generated falls even more than the voltage but this needs a sensitive ammeter linked to an oscilloscope to be accurately measured. It is this loss of spark energy that often causes poor starting even though a spark can be seen when the plug is out of the engine. Quote Link to comment Share on other sites More sharing options...
axulsuv Posted May 26, 2015 Report Share Posted May 26, 2015 (edited) As Furse Said , Check The resistance and check the trigger too , The Dansi ign. is much stouter than the Motoplat used in the early 240's , Like he said , late model CDI coil and go from there , The primary coils usually are good or bad/open not much in between , if it loses spark when hot then go for the rewind ... fantic_240_electrisch_schema_1982.pdf These should get you started , all the fantics are about the same ... Have fun , I know you love the bike or you wouldn't of bought her back ! Glenn , The one you have to download is a colored schematic ... Edited May 26, 2015 by axulsuv Quote Link to comment Share on other sites More sharing options...
ianpr2 Posted August 27, 2015 Author Report Share Posted August 27, 2015 Hi, I am still battling with my 300 Spark Problem - got put on the back-burner for a while..... I want to get the Flywheel off to check the coils but I need to find out what the Flywheel Puller looks like. I know someome who possibly has one locally (in Cape Town). It is in his workshop - as he last used it a while ago, we need to know what we are actually looking for. Anyone got a picture or a drawing of one?. Thanks Ian Quote Link to comment Share on other sites More sharing options...
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