Hi. I have been having some problems with my bike. It's somewhat of a mutt. 1988 bike, with a 2001 motor (883). The wiring is butchered. I have repaired some of the bad connections, but not every single one. The battery connections are good. I took off the voltage regulator and made sure it was making contact, and cleaned it off so it was grounding.
The problem I have been having is that the bike doesn't run as well with the lights on. It stumbles a bit when I turn them on. It runs pretty well with them off. It even changes the idle speed a bit if I step on the brake and the brake light comes on. It is a little worse if I hit the horn while riding. It doesn't seem to be running the battery down while riding, I can ride for hours, and it always starts right back up no problem.
I found some tests and used my multimeter and the reg seems ok. For the stator, I checked both pins to ground and found infinate resistance. When I measured from pin to pin, I THINK it said 1.9 ohms, I can't remember, I lost the paper I wrote it on. I can recheck this easy enough. I am wondering if this means the stator is toast? I have not tested it while running yet.
I put the meter on the battery terminals, with the bike off it was 12.6 volts. Start it up and it was idling at around 13.5 v. It was idling a bit low, turned the idle screw a bit and it was at 14.5. It never went higher no matter how much I revved it.
I am planning on going over every wire on this bike, and making sure I have good connections everywhere, which is a good idea regardless. The battery is about 2 years old, and is kept on a battery tender when I know I am not going to be using it for a long time. It has not been on the tender since last spring.

 

if i were to guess I would say that the stator winding are badish...from your description the stator is not making the correct amount of amps to supply the electrcial system, so when you run a lot of electrical stuff it can't keep up...but the first thing I would do is load check the battery...just because the battery voltage is good does not mean it has the ability to provide the full current (amps) needed for the system...as a battery goes bad (sometimes) it will lose its current making ability and act as if it has gotten smaller, while still running at the correct voltage when charged...

 

thanks. am afraid the stator is on its way out. i can easilly get it load tested. i have never had a problem with it not charging when i ride it (yet).

 

I discovered a problem with my cheapo harbor freight multimeter. When i touch the leads together, it doesn't go to zero. It goes to about 1.5 ohms. That has me thinking, it read 1.9 ohms between the terminals on the stator plug. Subtract the 1.5 ohms where it should be 0, and i get .4 ohms, which is in the normal range.
I am now questioning the voltage regulator. If it is the regulator that belongs on an 88 bike, it is probably an 18 amp. The stator on the 2001 motor is 22amp. I am wondering if it was mismatched, would that cause problems like this?

 

If you are 12.6 shut off and 13.5-14.5 then you are charging just fine.
Sounds like you have a problem somewhere between the battery and the ignition so that when you turn on the lights you are not getting enough current to the ignition, so get out your schematic and start running down the connections. Check the voltage at everyone along the way and see where you are getting your voltage drop. Look for wires that are twisted together, not soldered right. Check your fuses, check your switches both lights and main ignition.
Clean all your connections with cleaner and then use a die electric grease.

 

If the engine is revved and the voltage doesn't change past ~ 14 volts, you have a healthy voltage regulator !

 

I thought just like you both mentioned that the stator and regulator were functioning correctly. I am going to check every connection. The wiring on this bike is scary. Aside from being hacked together the bike used to be stored outside.

 

If you're measuring 14.5 VDC at a fast idle (according to your OP) with the lights ON, I don't think there's anything wrong with the charging system. I'd be looking for bad electrical connections, starting with both ends of both battery cables, then moving on to the fuses and connectors.

If you haven't replaced the spark plugs lately, I'd do that as well, they're cheap.

 

.3 ohms on a borrowed better quality multimeter. Spark plugs are a couple months old.

 

What is .3 ohms
What is the voltage at your head light?
What is the voltage at the coil with head off and on?
Check it with the bike running the subtract it from your battery voltage that is your voltage drop due to bad conections.
The idea is to get these two numbers as close as possible with as little drop as possible.
Then get back with us.