Ok so was heading J&S yesterday with bigtartyboi bike started fine. Stopped of in frodsham for cash machine jumped on bike and it wouldn't start (relay wasnt spinning-less than 3month old). Bumped it n carried on (starter relay span while engine ran if pressed) as expected had to bump when leaving J&S and every other time I turned off the bike. But then the light started dimming, horn stopped working ect all signs of a dead battery, first thaught replace the rectifier.. have done and charged the battery. But still relay ain't spinning all lights dim horn won't work and hen I bump start it'll cut out after about a minute. As far as I can tell all my wires are ok. U guys any idea what could be draining power ?
Lights dimming when engine is running, sounds like your charging system is kaput! Speak to @ExOldRacerGit as he recently went through a similar ordeal and eventually replaced parts of his Honda CBR600F charging system.
Get a volt meter on it - you should get usually 13.8 - 15v on most systems, lights on or off. I think from my past experiences, on a T3 Guzzi, a GT550 Kawasaki and a Triumph 900, you will find you get battery voltage +0.2 - 0.5volts with the lights off and somewhere below battery with the lights on. It sounds to me like a broken / loose wire for the load sensing circuit, so changing the reg/rec won't make any difference. Jury rigging a battery +ve feed into the sensor wire point will show that up as it will start cahrging higher. Tracing the faulty wire will probably be a bugger though. I'm sure Cabernet remembers the fun and games when the Guzzi did exactly this sort of thing while in Belgium years back and I had friends front and rear as my lights coming back 50 miles from the port in the dark.
Battery looks a little dud.. Less than 2 month old or is t normal to look like this.. View attachment 764 View attachment 765
Sometimes the easiest wire test is to rig up a new one round the outside, fed into the back of the connector blocks on the section you are testing. Effectively doubles your circuit route for it, one wire at a time. Can be easier, particularly on circuits that are internally broken and still making intermittent or poor contact. Also if you find one that way, check that the connectors in the end blocks are secure (retaining tang not broken off / bent), intact (not corroded or full of shit), not burned out/melted. I've had all of those faults over the years and they can be sods to find.
