Dakota 350 electric problem

[Karel Dakota 350]

Hi, my dakota has a problem with spark. Bike wont start. I tested three types of spark plugs. Sometimes is spark good sometimes not and sometimes no spark. I measured the ignition coil impedance and thats not 150 ohm as is written in manual. I measured only 1,6 ohm. Is there someone who can measure it for me please?? Is the value in manual ok?

And the second question, what is this part on foto? Is this the diode? What values and if yes, what is the current electric direction?

Sorry for english, i am from Czech republic an my italian language is on zero level.

[Matte]

Yes, it seems to be a diode (it's like a bridge with a diode inside to permit the current going only in one direction), normally on the body you can find the "name" of the diode himself and with it you can find the specification. The direction of the current is marked by a white collar on the body of diode, at the same time you can easily find it using a multimeter.
The coil, you checked the primary winding (LT), or the secondary (HT)? I suppose the value on the manual is ok.

Ah, welcome in the forum . Make your presentation in the section "presentazioni"

[Karel Dakota 350]

Ok, thank you. Do you know why is the diode in circuit? I know what the diode is, but dont know why is in this  motorbike electric circuit. The data from my diode is unreadable.

In dakota workshop manual they test only primary winding of the coil. It is shown on the photo in the same workshop manual. And they say i may have 150 ohm impedance.

I cant find dakota er350 electric wiring on this forum. Can you help me?

Thank you so much. 

[Matte]

The first thing should be to understand if that bridge it's an original "equipment" or someone did it (I'm not so sure it was made by Gilera). The diode probably is a 1N4007 (1 kV, 1 A). I can't help you for wiring diagram of Dakota, sorry.