Voltage Drop To Coils

[Guest]

I have been having a starting problem with my 82' GS550L. I checked for voltage when running and I'm getting 13v at idle and around 14v at 4000rpms. But with the headlight on I'm only getting 12.5v at idle.

But I checked the voltage drop at the coils and I'm getting a 1.7v drop. The bike has a hard time starting, when cranking the battery reads 10v, so that tells me at the coils I'm getting 8.7v while cranking.

If I put the battery charger on the bike it fires right up. if not it will just turn over but not start.


I did just replace the stator and regulator. So the battery is probably pretty weak. What should my voltage would be at idle with loads like the headlight taillight on?

What should I check?

Thanks

[posplayr]

See the quick test in my signature. Do the test and report back the results. Also see gs charging health. You probsbly have dirty connectiond affecting charging as well as coil voltage . If the battery is known low then charge it first before proceeding.

[curtie94]

I did your tests and I noticed the stator wires where running through the harness still, so I wired them directly to the RR. now I'm getting 13.5-14v at idle. as the rpms rise is goes to about 14.5v.

But I'm still getting voltage drop.

I cleaned up the harness a little bit this morning and i managed to get the voltage drop down to about 1v. which to me is still high, I like to see lower then .5V

Is there anything else I can do to get the voltage drop to a minimum?

I checked at the fuse block and to the red fire form the battery there is 0v of drop. but to all the key on power (orange wires) I'm getting .7-.8v of drop.

What can I do?

Thanks

Curtis

[Steve]

I checked at the fuse block and to the red fire form the battery there is 0v of drop. but to all the key on power (orange wires) I'm getting .7-.8v of drop.

What can I do?

The only thing between the red and orange wires is the ignition switch. You have to remove the headlight to get to it, but it's not all that bad after the light is removed. When you get the lock assembly off, the electrical section is at the bottom. Just a couple of screws hold it to the lock assembly, be careful when you take it apart, there might be a couple small parts loose in there. Clean all the contacts well (don't forget the 4-pin connector that feeds the switch), instal some dielectric grease and put it back together.

If that does not fix your voltage drop, you can install a relay between the battery and the main fuse. Use the orange wire coming from the key to trigger the relay, you will get full battery voltage to the fuse box.

.

[posplayr]

0.7-0.8 volts is really not that much on a stock wiring harness even if it is "pretty" clean. You need a relay to circumvent the voltage drops to the coils due to the multiple connections going from battery==>fuse box==>ignition switch==>back to fuse box==>kill switch==>coil.
You can get rid of most if your clean everything. DeOxit or equivalent is easiest. The wire contributes some, but it is the lessor of the whole drop you are experiencing.