That definitely sounds like a phase down now if that was a 50 amp alternator you could probably survive like that for years and not notice if you don't run aux lights, heated kit etc.
Its worth remembering that the same alternator but with a different drive interface was fitted to most of the single spark 4 valve r bikes.
I've attached a excellent PDF on alternator R&R for additional reference.
Trouble shooting a battery draining short:
Please read these instructions all the way through before proceeding. If you have never used a VOM before, get help from someone who has. Please have him or her follow these instructions carefully. Do not assume because someone has a VOM and has used it that they will know how to do these tests.
You will need a VOM meter for these tests. A digital VOM will be best. You'll need one with a high Amp feature of 10A at least. A pair of jumper wires with alligator clips will be helpful but not absolutely necessary. It will help to have an assistant.
Do these tests out in the open if possible. Please be careful around batteries as a spark can make a battery explode under the right conditions. First, remove your bike's main ground wire from the battery NEG post, and any other grounds attached there. Move the NEG leads down and away from the battery before proceeding. If you have more than one NEG lead on the battery you will have to join them using the battery nut and bolt. Again do not create sparks near the battery.
Use a VOM on high Amp setting (usually 10A). Usually this means moving the VOM's POS lead to the high amp (10A) socket on the VOM. Set the VOM for high current reading.
Your VOM should be placed well away from the battery and connected using jumpers with alligator clips. Do not place it on the seat above the battery, but rather on the floor beside the bike.
Connect one jumper to the battery's NEG post and its other end to the NEG VOM lead. Then, then connect another jumper to the ground leads you took off the battery and the other end of the jumper to the VOM's POS lead. This way your last connection is well away from the battery to avoid sparks near the battery
When first connecting the last jumper connection, be careful. You might have a large short that is greater than the VOM's 10A ability. In that case your battery would discharge very quickly, so it is not likely. This article assumes at this point that you have a small drain on the battery, but rather than blow the fuse in your VOM, be careful and disconnect the VOM from the jumper immediately if it shows a very high reading or sparks fly.
It is likely you will see a reading less than 1A. Even a small current like 200 milliamps can drain a battery in a few days or less depending on the charge of the battery and its state. Any current higher than about 5 milliamps (no clock) is a problem. Ideally your VOM should read zero as in no draw on the battery. I will now assume that you have found some current draw, that's why you're reading this in the first place, because a problem is draining your bike's battery. Now you have seen it and know for sure.
Most clocks will drain maybe 20-40 milliamps. If you see more than the normal clock current you know you have a problem. If you can, disconnect your clock if you have one, this will make testing much easier. Or if you can find out what your clock's drain should be that will help.
So you now either know you have a short somewhere draining the battery, or you know you don't have a short. Another possibility is an intermittent short. You might only have a problem for example when it rains and there's more moisture. Or there may be something that causes the short which is missing, switched off, or different at the time of testing.
This article assumes that your battery has been going dead when your bike sits for awhile. With a decent battery, a clock should not drain the battery for several months. So let's assume at this point that you found too much current being drained from the battery and proceed with the rest of the testing.
You might want to have an assistant to watch the VOM for changes during the following tests.
Pull one fuse at a time until the VOM reading drops to zero. After pulling one fuse and checking the VOM, replace that fuse so you don't mix them up. Don't forget any fuses which are in a fuseholder on any accessory circuit that has been added to the bike. In fact, check those fuses first.
Once you pull the fuse which causes the VOM reading to drop to zero, you now know the circuits(s) where the problem is. Note that if the problem is on the clock circuit and your clock is still connected, the reading will only drop to the clock current level. In this case disable the clock temporarily. There is likely a connector on it's wires you can unplug. But also check the rest of the fuses while you're there.
Note which fuse is the suspect. Look in your owners manual or wiring diagram to find out which circuit(s) that fuse controls.
Now you'll have to work with your wiring diagram while physically examining the circuit which is the problem. If possible make a blow up B&W photocopy so you can trace the wires using color markers, using a different color for each circuit on that fuse. If you're lucky it's only one circuit with one load on it. This will allow you to easily find and trace the wires you need to.
Now you have to find where those wires and their connectors are on the bike. You're looking for places where the wire may be pinched, broken, or dirty. It is very likely this is close to the steering stem or where it exits the tank, on a connector, where the loom bends, around the radiator, seat, etc. Check the easy places first. Look for physical damage, look closely.
Look for the wire(s) by color. Note that your bike may have different wire colors than the wiring diagram, it is possible. If you know which device the circuit is powering you can work back from that device, noting the wire colors and verifying them on the wiring diagram.
As a last resort you might have to strip some wires out of the loom, but before going that far, examine the wires where they are in the open, and their connectors. Hopefully the problem will be found.
If you can disconnect some connectors along the circuit you can then know whether the short is upstream or downstream from that connector.
Depending on what is on the circuit you may disconnect the load and check the VOM. For example if it's the headlight circuit pull the bulb(s). Sometimes a bulb will short circuit internally and you can find the fault this way. In the horn circuit disconnect the horn and check the VOM, etc.
Grease or oil or water around connectors can sometimes create a short to ground so clean anything suspect. Look for the easy stuff first. It's rare that a wire gets broken inside a sheath of wires unless there is physical damage evident so look for damage.
Look at the wires where they are exposed and connected first. Hopefully the problem will be easy to find. The main thing is to find out which circuit has the problem. After that you have to find the problem. This is a good time to check all the wiring on the bike. If you have one problem, there may be more just waiting to happen.
One more thing. It is not that rare that more than one problem exists. The VOM reading is key to finding if you have one or if you have more than one problem. You may find that theh VOM reading drops when you pull one fuse, but not to zero. Leave that fuse out and pull the other fuses one at a time in that case until the VOM reads zero.
