Starting the bike it makes a half assed cranking noise then rapid clicking. To me this is a sign of low battery voltage- confirmed with a volt meter around 12 volts. However, the battery took a charge with a trickle charger and was able to start the bike. What I'm unsure of is whether its my battery or alternator. How can I measure the output of my alternator? When does the bike switch from using the battery to the alternator? Of course, the bike dies without the battery in the loop and jumper cables are removed so cant test voltage there. I did replace the gasket on the alternator cover -could I have messed something up there?
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Fin
The most likely thing is that the battery is on its way out, even a dead-on-its-feet battery will show about 12v on a multimeter, its the ampereage that coumts.
Obvoiusly you don't want to buy a new one if it is a faulty charging mechanism. I do not have the figures for the GS but my Haynes manual for my Yamaha XS400 says to test the alternator put a test meter across the battery terminals, start the engine, hold at 2000 revs and you should get a reading of 14.5v plus or minus 0.3v. The bike is very similar being a 400 paralell twin so I would expect the figures to be there or thereabouts.
Suzuki states 13.5 to 15.5 V at 5000 rpm at the battery
3x 75 V for the unloaded alternator at 5000 rpm
Yeah Markus sounds like he has the right numbers, but if the bike dies when the cables are removed, you definatly have a broblem. If your battery is totally shot it may die once the cables are removed, but if it can hold 12v it should at least run for a little bit. You could try jumping it from the smallest battery you have, without the vehicle running, and checking the voltage. If you rev it up to 5,000 rpm, even while hooked to a jumper battery, the voltage will stedilly go down if the alternator is shot, and it should be arround 14.25 or so if it's working properly.
If it dose this while hooked up to the jumper battery, then dies with the cables removed there could be a short in your battery or something, but if the voltage is decreasing then your alternator is shot. Or it could be the regulator/rectifier/black box. I hate electrical shaZam!. :mad:
Good luck :cheers:
The engine shouldnt die when the battery is taken out of circuit. The fact it does suggests there is no generated voltage present in the bikes electrical system. The engine is running on what is in the battery and at the same time is not charging it, just slowly draining it, when it fully drains or is removed the engine will stop as there is not enough current present to generate a spark. If you have recently been working around the alternator its not unrealistic to suspect the fault could be related. I would remove the cover and be looking for trapped and shorted and/or broken leads. Identify the 3 leads from the alternator winding and check them for circuits, yellow, white/green, white/blue, there should be three balanced resistance figures across them and a open circuit or very high resistance to earth. If this proves ok the next step is to check the voltage output. Get the bike running at 5krpm, disconnect the 3 alternator leads at the regulator/rectifier and check the voltage across the 3 phases, anything under 75vac indicates a faulty alternater. I have lifted this info from the service/workshop manuals. They quote very good step-by-step troubleshooting procedures relating to the electrical/charging system and quote static and dynamic go/no-go test figures for the components. You should get one and follow the instructions you will find it a big help.