Home. Back. ...... The Gas Gas Guru. Technical Information.
Hi Jon,

firstly thanks for the tech info on your webpage, its the best source I have found. I live in the UK and have a 1994 250. I need some advice please!!! I have had a problem over some months where the bike has become increasingly difficult to start. the only way I could get it to start was be closing the plug gap to less than the recommended gap. It now has got more severe, and the bike will not start with the gap more than .007"(seven thousandths of an inch). I have checked electrical connections, cleaned the earth at the rear of the CDI unit, made off new ends both ends of the HT lead from the CDI to the plug, but still the same. I suspect the magneto coils or CDI unit are at fault, so I looked at your wiring diagrams, (http://www.gasgas.com/Pages/Technical/Electrics/wiring-ducati.html) the diagram is excellent, but the font is a little small for me to read the resistance value on the various leads and windings. Could you possibly send me the ratings in an Email? Any other suggestions greatfully accepted, Many thanks keep up the good work

Sean,Wales UK.


Thanks for the compliment. Sounds like you have done the necessary initial things to check out the possible problems. It does sound like weak output from the ignition system to me too. The plug electrode gap should be set at approximately .020" in the older type Gas-Gas for best results rather than the .024" of the new models. I like the Platinum or "rare earth" type plugs as I found they take less voltage to fire and have a slightly extended heat range compared to the regular thick electrode plugs.
Here's the spec's for the electrical system:
Black Ignition "Box" (module)
Terminals at the box
White-0 Ohms
Red-474 Ohms
Green-88K Ohms
Black-infinity reading (this is the kill switch wire)
Connecting wires to the Black Ignition Module

White-Connects to ground
Red-102 Ohms
Green-471 Ohms
Black- Infinity (push kill button, it should then read 0 Ohms)
Silver box on frame (Rectifier/voltage regulator)

Center terminal-Less than 1 ohm with bike not running. 9.5 volts AC with engine running.

Yellow wire-Less than 1 ohm with bike not running. 13 volts DC with bike running.
Thermostat switch
Blue wire-2.87 Meg Ohms
Red wire-Less than 1 Ohm

Let me know if this is what you needed. Good luck.

Almost forgot!

The spark plug lead is 5.35K to 5.29K Ohms. Just to make sure you have all the info.


Jon, thanks for getting the info to me so quickly, I think a night in the garage is on the cards for tonignt! I am assuming that the ohmic values you have given are for between the test point being measured and ground? Please confirm if this is the case, thanks Sean.


Right, that's between ground and test point. I got them from the owners video for the 95 JT25, Ducati Ignition, done by Jim Snell. Let me know if
you need any more info. I don't have all the answers but can contact people who do.


Professional tuner and 'Trials Competition' writer Jon Stoodley has very kindly stepped up to the plate to answer your questions. If you're having problems, or need some advice just send an email to Jon. If it's something that could be useful to others, we'll post it on the site.
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