where's my volts?

htown16 · Mar 24, 2018

Newly rebuilt 74 Commando, Pazon ei, new Motobatt AGM battery. Seems to want to idle and pulls good in midrange. But off idle up to midrange, popping and banging like ei not getting enough voltage
First test, hooked ammeter in line with wire to battery negative, headlight off. At idle 0 amps, rev it up goes to maybe 1 amp. Should be 4-5.
Second test. 1 Ohm resistor hooked to alternator leads and voltmeter set on 10 volts AC. Pegs the meter when engine is rev'ed, so alternator is good.
Third test . 1 Ohm resistor, negative lead to Podtronics black wire(connects to brown/blue feed), positive lead to ground. Voltmeter set to 10 volts DC, at least 8 volts when engine is rev'ed. Podtronics is good.
Fourth test. Voltmeter on battery positive and negative terminals, start bike. Idle it's around 12.5 volts but rev it up a little bit and the volts drop to maybe 8 or 9 and the backfiring and popping start.
What gives?

oldmikew · Mar 24, 2018

htown16 said:
Newly rebuilt 74 Commando, Pazon ei, new Motobatt AGM battery. Seems to want to idle and pulls good in midrange. But off idle up to midrange, popping and banging like ei not getting enough voltage
First test, hooked ammeter in line with wire to battery negative, headlight off. At idle 0 amps, rev it up goes to maybe 1 amp. Should be 4-5.
Second test. 1 Ohm resistor hooked to alternator leads and voltmeter set on 10 volts AC. Pegs the meter when engine is rev'ed, so alternator is good.
Third test . 1 Ohm resistor, negative lead to Podtronics black wire(connects to brown/blue feed), positive lead to ground. Voltmeter set to 10 volts DC, at least 8 volts when engine is rev'ed. Podtronics is good.
Fourth test. Voltmeter on battery positive and negative terminals, start bike. Idle it's around 12.5 volts but rev it up a little bit and the volts drop to maybe 8 or 9 and the backfiring and popping start.
What gives?

Leaking to earth.. presumably the zenor is disconnected as you have Podtronics , what about the big blue capacitor , try disconnecting and see if that resolves your problem

htown16 · Mar 24, 2018

Thanks for the suggestion, it led me down the right path. No capacitor and no zener, but in a bit of brain fog, I had put a piece of shrinkwrap on the bare ends of the brown/blue and red wire to the missing power outlet, essentially joining them together. Bare ends cut off and each one shrink wrapped by itself. Seems to have solved the problem. The joys of sorting out a new rebuild.

where's my volts?

htown16

oldmikew

htown16

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