Topic: CB650 Hybrid charging

[Scott S]

 Bike is a '71 CB500 with '82 CB650 engine and carbs.

 After poring over multiple wiring diagrams and consulting with a friend who is an electrical engineer, I spliced together the wires coming from the CB650 alternator (stator? Field coil? The three yellow wires, neutral, oil pressure, etc.) with the correct plug from a 500.
 That way it plugged right into my 500 wiring harness and I was able to use the existing regulator and rectifier, which are separate units on a '71 CB500.

 Tested the stator before installing: Passed. Tested the rotor, and it failed, so I replaced it with one that tested good. I did NOT do anything with the brushes other than visually inspect them. They were nice and long and it looked like both had been contacting the rotor.

 Bike cranks, starts, idles and runs great. I tested the charging system with the bike running.
 Headlight OFF: 15+ volts
 Headlight ON:  13.9 volts
 headlight HIGH: 13.3 volts.

 I would like to see over 14 volts, but this was just sitting in the garage and revving the engine. I've yet to attach a voltmeter and actually ride the bike to test charging.

 Long winded.....stick with me.....

  About 100 miles on the engine swap so far. Tonight, I went out for a ~20-25 minute ride and all was well. Just got of I-77 and was waiting at the traffic light at the end of the off ramp when my hand brushed the kill switch by accident. When I tried to restart the bike, it was sluggish and the battery barely turned over the starter motor/engine.
 
 Tried briefly to push start it, but noticed that the battery tried harder if I waited a minute or three (headlight was off). After sitting in the median for about 5 minutes, it turned over...sluggishly...but started. Rode home with no problems and put my voltmeter on the battery: 12.10 volts. Tried to restart in the garage and same thing, and noticed that the voltage dropped as the starter motor tried to turn over....8.something, 6.something,...
 
 I have it on the charger now and it's up to 13.1 volts. Cranks up immediately.
 What should I investigate first? We know the rotor is good. I check the stator (you helped me over the phone). The brushes look OK, but maybe I should replace them? There's not much I can do about the regulator, is there?

[Scott S]

 Also, I unplugged the battery tender before I went to bed and the battery had 13.1 volts. This morning, after sitting overnight, it tested at 12.6 volts.

[scunny]

battrey is fine, you will find the trouble with your hot start issue is the solenoid, or earth to your frame. 

[scunny]

try searching for "hot start issue" kit had the same problem.

[Scott S]

 Solenoid...Hmmm...I wonder if the 500 starter solenoid is not compatible with the (larger?) CB650 starter?

 That's probably the original 40+ year old CB500 starter solenoid on there, too.
 I feel pretty confident about the battery ground, as I cleaned the strap, frame and bracket there. Are you talking about another ground?

 Off to search "hot start"....

 BTW, I've done multiple stop/starts on this bike when tuning, but that was probably the longest single stretch of riding after the swap. (Also...I had just taken her up to 95 mph on the interstate and she was still pulling when I chickened out....shhhh... I did let her coast back down to ~60 mph for a mile or two before the exit ramp).

[Scott S]

 Found the thread and linking it here for ease of use:

http://forums.sohc4.net/index.php?topic=42826.0

[Scott S]

 Still reading through Kat's thread....

 This morning, I pulled the alternator cover and cleaned the rings on the rotor with 600 grit sand paper and some electrical cleaner. There was evidence that the brushes ARE contacting the rotor. Tested the rotor and got 4.5 ohms.


 Speaking of brushes, here's a pic of mine. Look brand new.


 Noticed the rust on the stator winding....probably from when I degreased the engine...so I cleaned it with 600 grit and electrical cleaner.
 Bike fires instantly and now I'm getting 14.7 volts to the battery with the headlight on and 4-5,000 rpm.

 I'll see how she does and if it continues to give me problems, I'll check the solenoid/grounds and maybe consider replacing the battery. It's about three years old now and I've had to top it off with demineralized water a couple of times over the years.

[iron_worker]

You sanded the windings? Seems like a good way to short out some of your windings? Or do you mean the magnet surfaces?

IW

[Scott S]

 Very lightly sanded the magnet surfaces on the windings...sorry.
 Just enough to get the surface rust off of them.

[curemode2002]

Couple of things to watch out for Scott S.

My old rotor tested great (5.2 Ohms) when cold but as soon as it hit normal engine temp I was getting no resistance at all (0.3 Ohms). So I had to get another rotor that held resistance when hot.

Test the resistance from the rotor brush to the connector at the rectifier you should have very low resistance .1-.2 ohms. When I depressed one of my brushes the resistance would shoot way up (65+ Ohms) then back down as I released pressure so that one was dead and had to be replaced.

[Scott S]

 Which wire are you testing at the connector? I know it's not the three yellow wires. I know which one is neutral and which one is oil pressure.
 Remember....I spliced in the connector from my CB500 to the 650 alternator wiring.

[curemode2002]

The rotor wires are white and black if memroy serves correctly. If you still have them bundled the same they will be the other two in the loom with the three yellow wires from the stator.

[Scott S]

 So, unplug it from the main harness and test resistance between the two wires? With the bike off, I assume?

[curemode2002]

Yes the bike off and from the terminals to the brushes you will want to depress the brushes during the test. You can also go from the Black to White and see the live resistance on the rotor.

[scunny]

my 650 started suffering the dreaded hot start issue. pulled the solenoid apart, cleaned up the contacts and haven't had the problem since.

[davesee]

i had the exact problem for a while, and cleaning the starter solved it for me.

[Scott S]

 I've only made it to page 6 of Kat's thread (lots of trouble shooting info in there that didn't solve her problem...yet), but can anyone cut to the chase and tell me about rebuilding the solenoid?

 I have a CB500 wiring harness and solenoid. Are they the same? Are they rebuildable? I can probably figure it out once it's in my hand, but pics or a guide is always helpful.

[Scott S]

 And maybe I'm just thick....but when you say cleaned the contacts on the solenoid, do you mean the posts or did you actually open up the solenoid and clean something internal?

[scunny]

opened the solenoid enough without unsoldering the wires, gave it a resonable clean and put it back together. hush did a wee walk thru I shall try and find it.

[Scott S]

 Cool. Just dug through my parts pile hoping to find one to experiment with or clean and replace, but all I found was one for a CB650 wiring harness. It has some plugs on it that the CB500 doesn't.

[bjbuchanan]

If it is like a 750 solenoid, which I'm pretty sure it will be It will be a flat copper bar that contacts on/off. Loosen up the plillips screws after opening up that wire crimp to hold the wires snug to the solenoid. Open it up while working the wires thru the cap and clean up the dark spots from the electrical connections, just the tiniest bit of dielectric grease on the exposed plunger shaft.

Without unsoldering stuff you could say it is a quick and dirty clean but it really isn't much in there to work over.

[Scott S]

 Well, I think cleaning the rotor and stator solved my problem anyway.
 
 I went on a ~112 mile shakedown ride today with my Dad. Lots of long stretches of 550-65 mph, some loops around the lake (still in top gear at 50+ mph), some back road riding, etc. Made several stops, from 2-3 minutes to 20-25 minutes. Always cranked instantly.

 When I got home, the header pipes were all under 300 degrees, the cylinders were 270 degrees and the battery had 12.65 volts.