Alternator: bad regulator?

[Inline4play]

So, I noticed there's about 70 volts coming out of one of the wires to the alternator. This is when the alternator is unplugged and measuring one of the two red wires from the alternator with respect to ground. When I do connect the alternator back up, each wire reads around 14-15 volts even with a fully charged battery. I understand the battery is acting as a load dropping the voltage substantially, but are these readings normal?

[Qweezark]

On the 98+ kats the voltage regulator of the generator is internal and shouldn't ever read over 14.4V. My book says 13.6-14.4 @ 5,000 RPM is typical. So when everything is connected properly reguardless if the battery is fully charged or not, you should be reading between 13.6 and 14.4 Volts @ 5,000 RPM. If it's reading over that when the bike is running it's fairly safe to say that the voltage regulator has gone bad or possiably burnt a diode or 2. I would suggest replacing it if you're getting more than that.

[Inline4play]

Well, with the battery connected, it falls close into that range, but we also saw it go to 14.8 to 15.2 volts with the battery connected.

Is part #10 all I need to replace the regulator?

'88 Katana GSX1100F
1: ALTERNATOR ASSY
[ALTERNATOR ASSY] 491088-001 $651.71
14-1: SCREW 466026-001 $0.55
19-1: NUT 467138-001 $0.97
23-1: BOLT 465855-001 $1.89
3A: COVER,BEARING 491165-001 $2.62
3B: RETAINER,BEARIN 491152-001 $5.88
3C: SCREW,BRNG RETA 491156-001 $1.33
3D: DISCONTINUED 491157-001
$8.61
2: FRAME DRIVE END 491150-001 $198.17
3: B1 15X35X11 BRN 491162-001 $16.82
4: ALTERNATOR ASSY 491206-001 $168.53
5: COVER, BEARING 491166-001 $2.62
6: B1 15X32X11 BRN 491163-001 $19.48
7: COVER(2) 491164-001 $2.62
8: DISCONTINUED 491161-001
$76.75
9: HOLDER SUB ASSY 491172-001 $133.33
10: REGULATOR 491568-001 $145.10
11: HOLDER BRUSH 491195-001 $30.31
12: COVER RECTIFIER 491198-001 $2.77
13: WIRE LEAD 491139-001 $15.71
15: WASHER,LK,4.1X7 467215-001 $0.86
16: SCREW 491199-001 $1.37
18: COVER 491169-001 $55.45
20: SERVICE KIT, AL 491213-001 $23.99
22: SPACER 491210-001 $10.57
24: GEAR,GENERATOR 487415-001 $91.47
25: HOUSING,GENERAT 487423-001 $43.48
26: DAMPER,GENERATO 487030-001 $2.29
27: WASHER 466848-001 $1.44
28: NUT 467170-001 $1.48

[Qweezark]

That should be all you need.

[Newbie2it]

And here I sit with one of these sitting right in front of me. I went to the local dealer due to an overcharging problem and suspected the same thing. The dealer told me they had one there, I tear apart the bike and get there with the regulator in my hand and nope, They didnt have it. I had them redline one from someplace overnight.

Put the bike back together and it was still overcharging. For me, in my instance, it came down to a faulty Ignition switch plug end. One end of the plug melted enough to cause it to overcharge at 15.2. When i would first start the bike it would be around 14.4 then eventually climb. The waire that cooked was the one coming from the alternator/battery. I had to physically unplug the ignition to see one end was discolored and melted slightly. Something to check before getting the regulator. I cant return the one I have, so now I have a spare for when mine does crap out.

Just my two bits

[kwebbel]

Check ALL wires and connectors, CLEAN them thoroughly, use some dielectric grease and check the voltage again.

Allmost dare to bet voltage will be fine....

[Inline4play]

thanks for the dielectric grease idea...low and behold it's now reading 14.38V at high idle (choke pulled out)

Last week when I read the 15.4 or so volts across the battery, the engine/alternator/regulator were warmed up.

after I put the dielectic grease on today, the readings were with a "cold" engine so the internal resistance of the regulator might be different than when read last week.

It's in a trailer in storage so I can't exactly get it warmed up and rev the engine past high idle. All I was able to do short term is pull the choke out and start it for 10 secs for this test.

so, is there a good chance it's fixed, or do guys that have been through this get 15+V with a cold startup?

[Newbie2it]

thanks for the dielectric grease idea...low and behold it's now reading 14.38V at high idle (choke pulled out)

Last week when I read the 15.4 or so volts across the battery, the engine/alternator/regulator were warmed up.

after I put the dielectic grease on today, the readings were with a "cold" engine so the internal resistance of the regulator might be different than when read last week.

It's in a trailer in storage so I can't exactly get it warmed up and rev the engine past high idle. All I was able to do short term is pull the choke out and start it for 10 secs for this test.

so, is there a good chance it's fixed, or do guys that have been through this get 15+V with a cold startup?

If the battery is totally up to snuff and it isnt loosing its charge, then on startup it might very breifly hit 15 but should return to 14 in quick time. If the battery is weak and questionable, then I would say theres a chance the regulator might be trying to play catchup with it. However, on cold start on my bike, with a new battery. (I just double checked it before posting now) When i start it I get 14.4. 5,000 RMP with the highbeam on is when you should check your readings.
Paul

[Inline4play]

Thanks for checking your voltage

coincidentally, the battery was just replaced 2 weeks ago due to it sitting while in storage. I purchased a solar charger for the new battery while this thing sits

http://www.batterystuff.com/solar-chargers/SP60-12.html

when I pulled off the solar cell yesterday, the battery read 12.8

when I turned the fuel pump on, the battery read 12.6. Then with the engine at high idle (no tach) and fuel pump on, it read the 14.38V.

I don’t have a headlight to compare with. It may sound odd that there is a fuel pump but it’s not in a bike and not a gravity fed machine

Sounds like I should be set; maybe I’ll install a digital voltage guage. Tough to decipher while in use between 15.2 and the 14.4 with the ol' analog gauge
Brandon