RS200-MII Charging Problem?

[BSOrion]

Thought I'd throw my biggest challenge out and see what the experienced folks may have to offer.  My BS has what I think is a charging problem.  It is an RS200-MII with a 175cc that runs fantastic... sometimes.  It usually fires right up an goes; however, it will eventually start popping and chugging out of one cylinder and will eventually die unless I immediately turn the key to kill the headlamp and run it without.  I've previously done some electrical testing that indicated the charging was borderline and the manual I have for the 175 DT mentions the following as potential culprits:
- selenium rectifier
- ignition coil (manual indicates that this coil is responsible for trickle-charging the battery
- key switch
As a hopeful and easy candidate in trouble-shooting this problem, I put a new, fully charged battery in it.  That worked for a few days but the issue eventually came back.
It seems as if it may be charging somewhat; yet, not quite enough to support running with the headlamp.

Any ideas or gut feelings to approaching this problem would be greatly appreciated.

Orion

[OldSwartout]

The charging system consists of three charging coils in the alternator, rectified by the selenium rectifier.  Two of the coils are used when running and the third is switched in when the ignition is switched to the lights position to provide extra current.  If any one of the sections of the rectifier are bad, the system won't keep up when the headlight is on.  You need to check the voltage output.  You should have 13 volts or more at 4000 RPM  with the headlight on. If voltage is low, check the rectifier first.  Also, if you are continually running slowly, even a good system may not ever keep up. Puttering around at 30 MPH in 4th or 5th gear will not work.

To check the rectifier:

There is a simple check on page 59 of the 350 service manual .PDF. That quick check will tell you if it is shorted. However, generally, I've found they have an open section or two. A digital multimeter doesn't work well to check those old selenium rectifiers as the meters don't provide enough current to distiguish well between good and bad junctions. You need an old analog meter or a battery and test light. To fully check the rectifier (with all wires disconnected) using a battery and test light:

1. Connect battery Negative to rectifier Black: test light connected to battery Positive should NOT light when touched to each of the other four terminals.

2. Connect battery Negative to rectifier Red: test light connected to battery Positive should light when touched to each of the other four terminals.

3. Connect battery Positive to rectifier Black: test light connected to battery Negative should light when touched to each of the other four terminals.

4. Connect battery Positive to rectifier Red: test light connected to battery Negative should NOT light when touched to each of the other four terminals.

Other things can be wrong: corroded windings in the alternator, bad or dirty connections within the wiring harness, disconnected wires, bad ignition switch, etc.  Check the voltage first, if not good and there aren't any obvious loose wiring connections, check the rectifier, then start tracing other potential problems.

I'm assuming the bike still has it's original style headlight bulb 25/35W.  If it has been replaced with something else (automotive, 65/65 W bulb), the charging system won't keep up.
Karl

[BSOrion]

Much appreciated Karl.  A good break-down on how the charging system works and what needs to be done to isolate the problem...

[BSOrion]

I finally got a chance to do some trouble-shooting.  I took your ideas to task on the s. rectifier with the following results:

1. Connect battery Negative to rectifier Black: test light connected to battery Positive should NOT light when touched to each of the other four terminals.  FAIL! All four lit-up

2. Connect battery Negative to rectifier Red: test light connected to battery Positive should light when touched to each of the other four terminals.  PASS!

3. Connect battery Positive to rectifier Black: test light connected to battery Negative should light when touched to each of the other four terminals.  PASS!

4. Connect battery Positive to rectifier Red: test light connected to battery Negative should NOT light when touched to each of the other four terminals.  FAIL! Bright on white terminal, dim on the rest

So, it appears that I need to replace the rectifier.  The only question I have... would it matter that I removed the rectifier before testing it... does it need to be grounded to the bike to conduct the test? 

[OldSwartout]

Unhook the wires, but it should not have to be actually removed.  Grounding to the frame won't change anything if all the wires are removed.

[BSOrion]

Great... thanks!  I've got a request in to Richard for a replacement.  I'm hoping that will do it.

BTW, just out of curiosity... is it feasible to upgrade the headlamp on these bikes without busting the 25W/35W capacity?  At its best, my headlamp is pretty dull and D.C. roads are dangerous as it is.

O -

[BSOrion]

Just received a rectifier that seller on eBay (well rated as was Jeff's) said was good and it failed the electrical test similarly to the one that came out of the bike.  It was $52.00

1. Connect battery Negative to rectifier Black: test light connected to battery Positive should NOT light when touched to each of the other four terminals.  FAIL! All four lit-up.  Yellow is bright and rest are dim

2. Connect battery Negative to rectifier Red: test light connected to battery Positive should light when touched to each of the other four terminals.  PASS!

3. Connect battery Positive to rectifier Black: test light connected to battery Negative should light when touched to each of the other four terminals.  PASS!

4. Connect battery Positive to rectifier Red: test light connected to battery Negative should NOT light when touched to each of the other four terminals.  FAIL! Bright on all terminals

Anyone know where to get a functioning rectifier?

[BSOrion]

I went for my first ride of the season tonight and with a fresh battery and new rectifier, encountered the exact problem I had before.  So, it's back to the drawing board.  Have some people to bug and some testing to do so will update in case anyone is interested.

Orion

[BSOrion]

All,

I'm going to remove the generator next and it appears the left crank case cover needs to be removed in order to remove the generator.  Looks like a fairly simple procedure and I also noticed there is no gasket for that particular cover illustrated in the parts diagram.  Anyone have experience with this on the 200s?

Thanks for any advice... Orion

[BSOrion]

Here's what happens if your bike was featured on the Red/Green Show...

There's a lot of duct-tape wrapped around the strands and the whole thing came apart with my bare hands... I had a puller ready to use but thought I'd give it a try anyway.  I'm thinking the bearing on the points end should have been more snug.

Anyone disagree?

Orion

[paul25g]

Orion,

Tried to get mine apart once but didn't have access to a puller.  Bearing was very tight.....no way it would come apart without a puller.  Just my experience, thanks!

Paul

[old smokey]

BSOrion - did you replace or rebuild the generator and solve your charging problem?

[BSOrion]

Smokey,  I found a replacement generator on e-Bay; however, when it arrived I found the housing to be damaged (mounting flange snapped off).  With Steve Reed's help, we were able to make a good generator out of my old one and the replacement.  Ultimately, I had two points of failure in the charging system.  Both the generator and the rectifier were not functioning properly.  After getting good AC from all three phases of the generator and employing a new silicon rectifier, I'm getting plenty of DC to the battery, keeping it charged.  I'm also keeping a eye on the battery to ensure it's not too much and so far so good.  I'm wringing out some other very minor issues with the bike but it's been fun to actually drive it.  I'm currently looking for my next victim.

Have a good one.  Orion