Bike stalls at stop lights? Carb or electrical?

[sgallaty]

did you replace your headlight bulb with an uprated bulb by chance?

Sorry if I missed it, but did you ever check +V across the battery with the headlamp on?

Erratic timing light can be weak spark.

 

[section8joe]

I think it dropped down about 2v when I switched the lights on. My headlight was bought at a swapmeet. I'm not even sure what in there. I'll have to check when I get Home. The past few months everything would charge fine with the lights on. This has been the first few days that the bike has been on the road though. Maybe something came loose? I'm just trying to find a place to start. My taillight also is burned out. Maybe something back there is causing it to drain the battery.

 

[sgallaty]

ahhhhhh -- you know what, I bet your taillight isn't 'burned out', but shorted.

I'll put some money on that your running light is shorting.

The stalling at lights may be the brake light trying to work...

 

[XSLeo]

Yes, legs. The alternator is a three phase. Each phase is a leg. So if one leg is not working a light load will seem to charge fine. Add more load as in the lights it can't make enough power to charge.
You need to go through all your electrics to be sure there are no shorts and good grounds. Then test your chargeing system.
Your repair manual tells how to check the charging system parts.
Leo

 

[section8joe]

Ok, taillight is burned out. I'm going to have to check my stator legs. Gonna suck because I solders my stator to rectifier/regulator and all my wires are wrapped up pretty tight. Can I just stick my voltmeter probe into each end of the wire wires(where they go into the stator and R/R) and check for connectivity?

 

[GBGRIDER]

It sounds like to me you have a straight ground in your lighting circuit. What i mean by that is you have a + connected to your ground some where. if your taillight blew out that might be a good indication to check there. I would tried to find a loose,crimped, cut wire some where in your lighting circuit. Good luck trouble shooting........PS if you are looking for a good small battery check this out..Shorai LFX14L2-BS12 it cost some dough what it is well worth it.

 

[XSLeo]

On the stator, it is a series of windings wired together in three groups. Each group is a leg. To do the ohm check it needs to be unhooked from the rest of the wiring.
To do the AC voltage check it needs to be hooked up.
If you can unwrap the three white wires to get to the connections then you can do the AC checks. With it running and checking white wires for AC voltage you should get better than 10 volts AC on each set of white wires.
If you don't get the 10 volts AC on white wires then you will need to unhook them to replace the stator.
I would reccomend using a plug like in the stock set up. Makes trouble shooting and replacement easier.
Leo

 

[section8joe]

I just took the bulb out of the taillight and I have connectivity from bulb to ground. I assume I should not have connectivity from bulb to ground right? I'm tracing it back as we speak. My taillight wire runs from my taillight through the fender and into my oilbag. I also cut the wire inside my oilbag and checked for connectivity. I check connectivity from the now isolated taillight wire to ground and I get no connectivity. Which I think I was hoping for. Now the other side of the wire(which is connected to everything else) still has connectivity to ground. Am I on the right track? Is there a way to isolate this without snipping all my wires?

 

[sgallaty]

Cut the wires in sensible places, install inline bullet connectors, would be my solution.

 

[section8joe]

So I'm on the right track? I should not have connectivity between my wires and ground right? Unless it's a ground wire.

 

[section8joe]

Alright, I think I made a bit of progress. I cut my blue problem wire between the oilbag and the headlight. I'm getting no ground connectivity on the oilbag side. I'm still getting ground connectivity on the headlight side. I have my headlight ground on the outside of the headlight ring. juice to the headlight is fed through a small hole in the headlight. The wire was rubbing on the hole but I don't see any cuts in the casing. I disconnected the wire and there was no connectivity to ground. I checked for connectivity to ground on the juice terminal of the light and there was connectivity. Is my bulb bad? Am I doing something wrong? Would this cause my bike to die when I hit the brakes? Here are a few pics of my bulb. It looks like its a bit melted but it still works. I left the pictures large to show detail.

 

[section8joe]

Ok, after everything said and done. I'm not sure If I made any progress. I cleaned the two rings on the rotor and I test the resistance. Everything checked out ok. I also measured the brushes and there were around 12mm each. I have my stator soldered to my rectifier and I'm not sure how to test the legs. I did test for connectivity by using the probes on the voltmeter and they seem to all have connectivity. I'm stumped and pissed so I walked away. I have no idea what else to do so that's it for the night. I appreciate everyone's help!

 

[gggGary]

Replace the brushes, near wear limits is not good enough. The XS650 uses up brushes, it's part of normal maintenance to replace them.

You should have a ground wire from the headlight back to the frame. Otherwise you are sending electricity through your steering stem bearings. Yamaha figured out that wasn't such a good idea about 1975. Brushes are the number one cause of charging system problems on XS650s, closely followed by or aggravated by, owners continuing to use bad batteries. Using a bad battery puts excessive strain on the charging system as it works endlessly trying to bring the battery up to proper voltage, which the battery can no longer achieve. Result? the charging system craps out under the abuse. A $40 battery replacement just became a $200 + troubleshooting nightmare.
To REALLY trouble shoot you will need to cut the connectors and measure the stator.

 

[section8joe]

I'm going to use curly's guide and trouble shoot the charging system. My brushes are 12
Mm. That's only 2 mm shorter them brand new. You think those are too small?

 

[gggGary]

S8J I didn't measure before posting LOL. Should be OK but these threads are for other lost souls as well as the OP too short brushes are the number one cause of charging system problems so I always bring it up. The curly's is good as far as it goes but needs to be updated with lots O pics and plain easy peasy test methods.

 

[section8joe]

I still haven't done curly's test but I did have five minutes today and I check voltage at my brown wire at the key switch. For some reason is was almost 2volts lower then the battery voltage. Maybe I'm onto something. Hopefully I can do a complete charging test tomorrow.

 

[GBGRIDER]

If i read what you said right, Your positive feed to your light has continuity to ground? That would be a big problem. Make sure you disconnected the ground wire from you light before you do that test. If it reads the same trace out that wire cause there is something wrong there.

 

[section8joe]

Yeah, I traced it to my headlight. I'll disconnect my ground on my headlight and let you know what I find.

 

[section8joe]

If i read what you said right, Your positive feed to your light has continuity to ground? That would be a big problem. Make sure you disconnected the ground wire from you light before you do that test. If it reads the same trace out that wire cause there is something wrong there.

I checked and I do have continuity to ground. I unhooked the ground at the headlight and the taillight lost continuity to ground but the headlight will not work. I ran a ground from the headlight bucket to the engine and the light comes back on but then I have continuity to ground at the lights again.

 

[section8joe]

I'm getting super frustrated with this whole problem. Everything seems to be working against me. My voltmeter broke and I bought a new auto meter from Radio shack and it's working weird. I lost the cover screw to my taillight and my taillight and brake light keep vibrating out of their holders. Plus it's hot at hell outside and my garage is hot and sticky.
OK, enough bitching! I charged my battery to 12.5v. I checked power to my coils and they're getting 11.15v. I'm getting 0.00 resistance between the power and ignition at the switch. Although last night I thought I was getting 0.5 but I could be wrong about that. When I start the bike at idle I'm getting 12.4 and 13.6 at 3000. When I switch the lights on I get 10.9 and 13. I tried to run the bike at idle with the lights and brake light on but the brakelight keep falling out of the holder with kills the light because it looses ground.
I started to do curly's test and I got to step one and I passed. My feeler guage pulled to the generator cover. What step should I do next? Curly's test is unclear. Should I go to #4 and check for voltage at the brown wire at the brushes?
My brushes are also fine but the left brush looks it has a weak connection. What do you think?