1200 LTD Alternator

[EasyBadger]

Hi Everybody,

I was always wondering why I'm getting always a hot ankle. I figured out, that the alternator housing is getting petty hot. I measured the amp. with my clamp meter and on one phase I got 18A on the second 15A and on the third only 3A. This sounds very unusual for me. The Volt meter on the dash shows around 13.7V while driving.

Any suggestions.

Safe rides,
Jens

[CrystalPistol]

The Volt meter on the dash shows around 13.7V while driving.

Any suggestions.

Safe rides,
Jens

13.7 … what are you wanting to fix?

[DaveO430]

Your stator is probably failing. Why that would make it get hot I don't know. Handy to have an amp clamp to check it with.

[Rednaxs60]

You are doing the readings with the alternator assembly hooked into the system. To properly test the output of the stator/rotor assembly you need to disconnect the stator wires from the RR and check the AC voltage on each leg, should be about 50 volts at 3000 RPM. It will fluctuate depending on RPM you should see the voltage increase from idle as you apply throttle.

13.7 VDC on the dash voltmeter is good, but if you want to check the alternator output (this is a 3 part alternator system consisting of a rotor/stator internal assembly and an external regulator/rectifier) hook a voltmeter up to the battery and go for a ride and compare the readings - you may find the dash voltmeter reading is a bit low.

What is the engine temp when you are getting a hot left ankle? These bikes don't shed heat very well and it bleeds most of the hot air from the engine compartment where your legs are. Both mine do this. It's especially noticeable in stop/go traffic, and city driving. It's also summer and this does not help reduce the heat signature of the engine compartment either.

Good luck.

[DaveO430]

You are doing the readings with the alternator assembly hooked into the system. To properly test the output of the stator/rotor assembly you need to disconnect the stator wires from the RR and check the AC voltage on each leg, should be about 50 amps at 3000 RPM. It will fluctuate depending on RPM you should see the voltage increase from idle as you apply throttle.


Good luck.

While this is a good test for most people who don't have the right tool for the job using an amp clamp, which he did, is a much better way to determine the actual output under load.

[EasyBadger]

Hi Ernest,

I think you meant 50V instead of 50amp. I thought about the warm air from the cooling system at first, but when I touch the alternator casing it is very hot. It is only on the left side. I am checking the system tomorrow further.

Safe rides,
Jens

[Rednaxs60]

Yes I meant 50 volts not amps.

I did a test of the electrical system on my Victoria bike and had approximately 17 amp draw at idle. You would like each leg of the alternator to be the same or close regarding amperage but I would submit that this may not be the case.

The RR has two outputs to the electrical system, one is a straight thru to the electrical system, the other is controlled by the regulator section of the RR that monitors the electrical system voltage and dumps excess current to ground. In other words it robs from the straight thru current and dumps it to ground.

I agree with Dave that checking the current is a way to monitor what the electrical system is doing. Doing this is one way of checking the electrical system, but you should do the other checks as well.

Good luck.

[DaveO430]

I agree with Dave that checking the current is a way to monitor what the electrical system is doing. Doing this is one way of checking the electrical system, but you should do the other checks as well.

Good luck.

Thanks but I wasn't referring to the entire system, just the stator output, it won't vary no matter what the rest of the system is drawing. On thinking about it some more if there was a problem with the rectifier it could cause the load to be different on 1 or more legs of the stator. The only way to be sure would be to switch leads and see of the load moved.

[Rednaxs60]

Agree. Switching the stator wires would provide an indication of where to concentrate your efforts, stator or regulator/rectifier - would still do all other checks. The RR after 34 years could have weak diodes.

Hadn't thought about the amp flow in the stator wires before, just the electrical system. To do the amp check of my electrical system I finally broke down and have a clamp on meter for DC amps - not that expensive and works great.

Cheers

[CrystalPistol]

In my experience with the 1200, that alternator case housing the stator and rotor and some engine oil, the housing bolted solid to the engine, will likely be near same temp as engine and hot enough to cook meat.

The 50vac test 3000 rpm across all three pairs of disconnected yellow wires will do. 13.7 vdc at battery with bike running is OK.

[EasyBadger]

Thanks guys for your suggestions. I cannot change the wiring so easily, because it is hard wired. Let's see how it goes until the end of the season.

On the weekend we are doing a 1000 Mile Cannonball Ride through southern Alberta and BC. There are 250, 500 and 1000 mile rides all over Canada.
Information at www.Cannonballrides.ca .

Safe rides,
Jens

[Rednaxs60]

Good luck and safe riding. Know of these rides, have looked into them.

Another suggestion, if you have a battery tender connection, you can get a battery tender voltmeter to plug into it. Would give you a more accurate reading of the electrical system voltage when at idle and on the road. There is also a USB battery tender unit that plugs in as well. Most bike shops have these.

Enjoy. Cheers

[EasyBadger]

My wife and I had a blast on our 1000 mile ride and the bike performed pretty good. From time to time it hesitates in the lower rpms. As longer we rode as better the gas mileage got, but with 6.6 l/100km it is still to high. I think, I have to ride more and long distances , because for a 33 year old bike there are 73000 km nothing. Now I rode it already 3000 km in 4 weeks. And by the way, the alternator is not getting as hot as it did before and the voltage is still good.

Safe rides,
Jens