Voltage Drop Question?

[Pigford]

Not related specifically to a Zed

My latest project (1980 Guzzi 850) is being a pain.

I have just fitted a h/d battery (replacing an older decent one) and still have a voltage drop issue.

The wiring is okay - there is a good +12v across the whole system including complete spark system.

When the starter is operated it spins nicely, but the voltage to the ignition (Lucas Rita) drops to just 10v

Lucas Rtia works well but needs the full 12v to work as it has a long dwell period, plus its 1980's technology!

Any idea's why the voltage drops so much - the new battery has 300CCA power and is fully charged - did it on older 190CCA battery too!

[z1bman]

does it have a bosch starter motor fitted ?

[Pigford]

No - Valeo

[z1bman]

i would have suggested the Valeo as the Bosch starter is known to draw more current but to be honest a 2 volt drop when cranking a twin is not that much . is it have problems starting ?

[Pigford]

i would have suggested the Valeo as the Bosch starter is known to draw more current but to be honest a 2 volt drop when cranking a twin is not that much . is it have problems starting ?

Yes, the Lucas Rita system needs the 12v to fire - it has a long dwell sequence and 10v doesn't do it

Thanks for your input by the way!

[walshyco]

Piggy how much current is the starter motor drawing ? Is it a new starter motor if it is drawing too much current you will get a volt drop.

[Pigford]

Piggy how much current is the starter motor drawing ? Is it a new starter motor if it is drawing too much current you will get a volt drop.

Hi - the starter looks original...... it's earthed well but had been standing a few years - wondered if the brushes could be shitty or the solenoid contacts dirty?

Not sure if I can check current draw with a basic meter???