Not charging?

The battery is 4 mo old, takes and holds a charge. However will gradually lose charge over time as I ride it. I have a maintainer that I use any day I don't ride, which makes the battery charge last longer, but will still drain off. Where do I need to check for voltage from the stator, and how much should I have at idle. I have another stator, and could swap it out in 10 min. I just want to make sure there aren't any missing wires or anything before I do. I also don't know if there is a drain on the battery somewhere while its sitting. I figure if the I am getting the right charge at idle I can look elsewhere for the culprit.
Thanks.

check the output at around 4000 and see if you get at least 14-14.5 volts dc at the battery. then go from there.

ive read here that short journeys at low rpm of which i am guilty of doesn't put the juice back in the battery.

new stator is a good idea im gonna get one too they are wound different so the give more juice at low rpm.

i also have a trickle charger always plugged in for now this works ok.

you will never get the proper charge at idle. you need to check it at a higher rpm.

Disconnect the alternator from the regulator/rectifier at the plugin. Get a multimeter,set the selector switch on Alternating Current (A.C.)with the range at 100 volts, have a person help as this can be difficult reading the output and reving the engine to 4K rpm's.

The output may vary from 50-70 volts(depending on the model of bike)This is what is changed to Direct Current(D.C.) to run the ignition and the bike's other systems.

If the output is low the stator of the alternator may be shorted internally and needs replacement.

The website www.electrosport.com has a troubleshooting diagram to aid in finding out if the alternator is bad.
www.rmstator.com and www.customrewind.com are two more alternator websites to look at.

I know you think your battery is OK. Most folks who have a bad battery think that. A bike battery is kind of junky made with too few plates and a tendency to sulfate. I have seen tons of 6-month old batteries hit the junk pile. Get a very small hydrometer from the auto parts store. They cost about $3. They look like an eyedropper. Find a small piece of hose and draw in some battery fluid from each cell as each cell must be tested separately. If any of the balls in the hydrometer fail to float, that cell is pretty much shot. If the battery passes muster, top it off with distilled water and take the time to check the connections coming off the battery. The black cable will go down to your engine or to the frame and must be securely fastened. The red connection will go to a lug on your starter solenoid. Make sure these connections are clean and then slather them with dielectric grease to ensure they don't oxidize in the future. You can get dielectric grease at an auto parts store.

If your battery is OK... go to the next step. Otherwise buy a new battery. If you do, charge it with a low amp (1A) trickle charger for at least 12 hours. Don't use a car charger as these charge to fast and lead to a very early battery death.

To clarify what MFolks suggested, if you disconnect the stator wires from the reg/rec, and you have a three wire stator (they will all be yellow or pink, blue and yellow, the three stator wires should be measured to clarify MFolks post. You put the probes of the meter on pair A & B, then A & C then B & C. You should see the same AC Voltage. I would put the meter on a lower range as well; perhaps 100VAC. You must measure between all three wires in pairs and check that the values are the same or close. I also don't believe you will see 70 VAC on any pair on a vintage Kaw... more like 35-50 VAC in my experience. If you get NO value between any pair, it means there is a short. If the value is low, it means the stator is OLD and partially demangetized.

If you have adequate voltage (35-50VAC on all three tests), then reconnect and stop the bike. Now put your meter on VDC in a lower VDC scale; perhaps 100VDC. Start the bike. Put your probes (red to pos and black to neg) on the battery and measure at idle. Normally you will see just a shade over 12VDC at idle with headlight on. Rev engine to 4K rpm and you should see 14.5VDC. If you see less... say in the high 12 volts range, your reg/rec is bad or you have dirty connectors coming out of the reg/rec and connecting to the battery OR main harness... this will be the white and/or white/red larger gauge wires. Disconnect these and clean with electric contact cleaner (spray) and daub with dielectric grease. You can find these two items at an auto parts store. Repeat the test and if you find that you still have low voltage at the battery at 4K rpm, the reg/rec is likely the culprit.