09-08-12, 02:20 PM
That rattle (the one that's not the fuel pump) may be what's known as the "Machine Gun Noise"...
It happens when attempting to start the bike with an "almost discharged" or "partly shagged" battery and it happens like this:
at rest ... 12V on the battery- no load.
Stage 1: Hit the start button. 12V on the relay coil. Relay closes. 100amps rushes out of the battery
Stage 2: battery voltage starts to drop (its supposed to go down to about 9V when its "cranking").
Stage 3 : Battery voltage drops below "hold voltage" for the relay (about 6V) ... Relay opens, 100Amps stops flowing.
Stage 4: Battery voltage recovers above 9V , relay closes again. 100 amps flows again.
Repeat from stage 2 about 10X per second.
Its a common symptom of a 10V battery (one that has 5 good cells and 1 shagged cell). a 10V battery will probably start the bike when fully charged on a nice warm day but will cause the "Machine Gun Noise" on a cold day or after the battery has rested for a few hours.
It happens when attempting to start the bike with an "almost discharged" or "partly shagged" battery and it happens like this:
at rest ... 12V on the battery- no load.
Stage 1: Hit the start button. 12V on the relay coil. Relay closes. 100amps rushes out of the battery
Stage 2: battery voltage starts to drop (its supposed to go down to about 9V when its "cranking").
Stage 3 : Battery voltage drops below "hold voltage" for the relay (about 6V) ... Relay opens, 100Amps stops flowing.
Stage 4: Battery voltage recovers above 9V , relay closes again. 100 amps flows again.
Repeat from stage 2 about 10X per second.
Its a common symptom of a 10V battery (one that has 5 good cells and 1 shagged cell). a 10V battery will probably start the bike when fully charged on a nice warm day but will cause the "Machine Gun Noise" on a cold day or after the battery has rested for a few hours.