Electrical Woes

[mrs minnesotamonster]

Bike: 2004 S4R
Mods: Open Air box, PCIII, Boomtubes
New battery this spring

Ok, this is going to be long winded, but bear with me. 

A few weeks ago I notice my bike has been harder and harder to start, taking a few seconds of pressing the starter, etc, but it would still start. Then, a couple of weeks ago, go out to start my bike to go to work, in the morning and the battery is dead. No big deal, Hop on the wife's bike, go to work. Get home, charge the battery in my bike (thinking the colder weather here had just taken its toll and since I hadn't ridden the bike in a week or two) bike starts. Ride to work for the next week, no issues.  Go to start the bike On Tuesday, Wouldn't start. Take wife's bike to work again, come home, charge battery. Take my bike to work Wed (yesterday) starts and runs fine.

Today:  Go out to start bike to go to work, starts up, (a little slow starting, but it was 40 degrees), go get gas, bike starts up again.  About fifteen minutes into my commute (stop and go traffic) I notice that the bike is idling low as I am sitting in traffic (700 rpms), when I get up to speed, it runs just fine.  After a few minutes off the odd idle issue, I'm sitting stopped again on the freeway, bike dies completely. Pull off to side of road, bike won't turn over, call the wife.  She brings battery from her bike, swap it out, thinking (hoping) that's what the problem is. Bike fires right up, ride the rest of the way to work (20 more miles), no issues.

After work:  Go out to start the bike, won't turn over.  Shit.  End up getting it started with some help from a co-worker and some trusty jumper cables. (no longer thinking I have a battery issue). Bike starts and idles fine for a few minutes.  Head back home.  About five minutes into some stoplights, bike starts stumbling, backfiring, surging, and not accelerating right between the lights.  Finally get on the freeway and up to speed (80 mph) and bike continues to surge/stumble/backfire constantly and not having much if any power. Unbelievably make it almost all the way home, exit the freeway, and I am keeping the revs high, at the light, hoping it would not die, make it through two sets of lights, when she finally stalls and dies.  Luckily I'm only two blocks from home now, and push her into the garage. 

Pretty sure my battery is no longer the problem.

Thinking something in the charging system?  All connections look clean and solid, although I haven't dug through it yet. Figured I'd get some alcohol in me and ask for some advice before I start to try to figure this out.

Ideas?

Thanks in advance

[Oldfisti]

Doesn't sound like the stator is charging the battery.

Bike runs on battery power until the voltage drops too low for the electronics to work.

[minnesotamonster]

Doesn't sound like the stator is charging the battery.

Bike runs on battery power until the voltage drops too low for the electronics to work.

my thoughts as well. Also thought maybe the rectifier/regulator?

[Oldfisti]

my thoughts as well. Also thought maybe the rectifier/regulator?

I would check to see if there was any voltage going to the rectifier while running. At least 14v I believe.

[Howie]

First step is check all connections.  Since you changed batteries those connections are probably good.  An excellent suspect is the engine ground near the breather valve.  Don't just look, take it apart, clean and reassemble. 

As far as the charging system goes, it is possible though it seems unlikely your battery would recover enough to run the starter, fuel pump and computer if the battery ran down enough for the bike to crap out.  Do not throw parts at it.  You can spend a load of money and still have the problem.

Here is a good trouble shooting chart:
http://www.electrosport.com/technical-resources/diagnosis-center/fault-finding-guide

Since your problem seems to be intermittent you might not get it first shot.  When things work they test good.  A common problem area besides the engine ground is the connection where the three yellow stator wires  plug into the regulator.

[ducpainter]

First step is check all connections.  Since you changed batteries those connections are probably good.  An excellent suspect is the engine ground near the breather valve.  Don't just look, take it apart, clean and reassemble. 

As far as the charging system goes, it is possible though it seems unlikely your battery would recover enough to run the starter, fuel pump and computer if the battery ran down enough for the bike to crap out.  Do not throw parts at it.  You can spend a load of money and still have the problem.

Here is a good trouble shooting chart:
http://www.electrosport.com/technical-resources/diagnosis-center/fault-finding-guide

Since your problem seems to be intermittent you might not get it first shot.  When things work they test good.  A common problem area besides the engine ground is the connection where the three yellow stator wires  plug into the regulator.

I don't think the FI bikes use that ground. There is a main harness ground on the other side IIRC.

[Howie]

I don't think the FI bikes use that ground. There is a main harness ground on the other side IIRC.

I think you are correct. 

[evoasis]

I had the same symptoms before my stator was changed out...

[minnesotamonster]

Ok so I finally dove into this. Battery tested at 12.5 volts cold, running at 3k it dipped down to 12.22. Checked the red/green wires from the rectifier, got 1.5. Tested all combinations between the 3 yellow stator wires at 4k rpm and got 45 to 50 and at 5k rpms got 65.

So from what I've read my battery voltage is too low, red/green from rectifier is extremely low and my stator is good.  Correct?

So I called around and none of my local shops have a rectifier in stock.  

So I glance over at the wifes bike and figure what the hell  

take hers out, replace hers with mine and test the battery.

Once again, battery is at 12.5 motor off. But now, with motor at 3k I'm getting 13.95. That's within normal range right?

Just want to be sure before my test ride as I don't really have a way of getting the bike home if she dies on me again.

Thanks!

[suzyj]

Once again, battery is at 12.5 motor off. But now, with motor at 3k I'm getting 13.95. That's within normal range right?

Yes, that's as it should be.

Looks like you found your problem pretty easily.