Yamaha Jog Non start

[Webbo1989]

Hi :

Got a Jog that has no spark - tested all feeds to cdi and tried a new cdi unit - still no spark - suspect a faulty magneto - anybody any experiance of these or can help ?

[baldy]

Try hard wiring it straight into the cdi from the magneto. You may have faulty wiring. Have you checked that the ignition switch is working? You can test by removing the black and white wire from it. Try it while this is disconnected and while connected. Have you also tested the pulse coil?
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[Webbo1989]

I have rechecked today and suspect the signal from the pulse coil as when measuring it on a scope i get the correct signal but only 4 volts - measure it's resistance and it's 175 ohms - the manual says 460-600. My question is : is this enough of a problem to create a non start / no spark ?

I have checked all wiring and power supplies to the cdi unit as follows:

Brown - ignition live 12v+ve
Black - negative 12v -ve
Blue / white - signal from pulse coil (as above)
Orange - output +ve to coil (has signal but very weak)
2 x black/white's - 12v -ve from ign switch when switched on

As explained above unless i'm reading the diagram wrong the black white from the switch should be earth when on therefore it will not run with it disconnected.

Am i right in the above and has anybody had pulse coil failure on these please ?

[Webbo1989]

Think I might have sorted it now - tried another cdi unit and this works - got a spark now but no fuel

The vacuum valve below the tank does not allow fuel out due to no vacuum in pipe - tested it with gauge and no suction !

Tried a compression test and getting 60 psi

Will investigate more tomorrow - off to pub now !