GS250TT Sometimes Sparks, Sometimes not!!!

[Guest]

Hi everyone! this is my first post and writing from Argentina.
I bought and restored a 1981 GS250TT. I almost finished but I have an electrical problem!
The motorcycle has spark on cranking every one or two times a press the starting push button.
Without touching absolutly nothing I crank the motor and have spark on both sparks and in the second or third atttemp it wont spark... then again i have spark...

Does anyone know what can be causing this behavior? All the electrical components had been tested according to manual and seems in good working conditions...
Please help!
Thanks a lot!

Ramiro

[barnbiketom]

What is the voltage to the coils ? use digital voltmeter on the + coil wire.. bet it is <10V

[dduberti]

Thanks for the quick response...
You were right... I checked Voltage while crancking in coils and voltage was 8,9 aprox... any solution i might attemp? Only by charging the battery should fix the problem?
Thanks in advance!

[AKC75]

I would start with checking all your ignition contact points and break out the contact cleaner. Freshen everything up and check all your grounds too. And charge the battery to full charge.

You may be looking at attempting an ignition coil relay modification as well. 30+ year old wiring tends to develop voltage drop by the time the power reaches the coils. So you get weak to no spark.

Things I've recently learned myself.

[dduberti]

Hi! I've been trying all day different alternatives but Im stacked...

Some extra considerations:
All the wiring is new.
Battery, TDI, Coils, coil wire and coil caps are new.
Charging system is disconnected as well as all lights and accesories. The only conected is the starter relay and motor and the ignition system.
Without cranking voltage in coils is same as battery 12.75 V
While cranking voltage in coils is 9 V. Can i improve this with a relay modification?
The engine starts and runs ok when i have sparks (1 out of 10 tries)
The other 9 out 10 tries there is no spark at all while cranking.
The signal generator has correct ohm reading according to manual... but maybe this is the problem?

Please help!
Thnaks in advance!!!
Ramiro