RLU help, etc.

[fiveohindc]

This is my first post, so bear with me. I searched the forum already, but can't find an exact answer to my question.

Just picked up a 77 XS650 at Vintage Moto Days. Previously I had a KZ440, and this is my second bike. I'm a newbie, trying to learn the ways of the force... It's been a mixed bag so far.

Love the bike, but today as I was leaving DC, within 30 secs of starting up, I had a plume of black smoke coming from my crotch. Yes, I'm a lady, and this made me panic. Turned off the bike, the Reserve Lighting Unit was smoking badly.

Even stranger, when I turned the bike OFF, the lights stayed on. The left turn signal, the rear running lamp, and the neutral switch. I was baffled. To quit the smoking and get home I unplugged everything I could get my hands on and made it without incident. (I really adored how the Stop Lamp Indicator flashed the entire way. Like, thank you, I'm not frakking moron, Bike!)

Once at home, I reaffixed all the wires. Initially the turn signals would not blink. Then, suddenly as if from the heavens, they did. Okay, whatever. The neutral light also began to behave, turning itself off when the key was turned to off. Whew.

Now the issue is, I can't turn on the headlight at all. When I do, the RLU smokes a ton. The switch also appears to be arsed, because I can turn on the HI beam, but not the LO.

I have read the bypass posts. I'm more of a mechanical gal then an electrical whiz. I read "jumper the -blank-wire to the -blankwire-" and my mind flatlines. I have solderless connectors, can I use those to rig the right colored wires together?

Also, could this be an indicator of a larger problem? Why would the RLU suddenly start smoking away like Bob Marley? Also, at the risk of sounding completely idiotic (maybe I do need that flashing indicator) but where is the fuse box on this thing?

I'm looking to buy a manual, but was hoping to find one in pdf first...

 

[nj1639]

Should be a single fuse under the right air box cover, near the starter solenoid......general area. The rlu can be jumped with your connectors. Trying to remember....blue/yellow to blue/black? Double check on that one and Welcome Aboard!

 

[fiveohindc]

Okay, update. I opened the headlight bucket this morning to find multiple wires fused together. It looks like Chernobyl in there.

The melting goes all the way to the switch at the handlebar. I'm in the process of untangling and freeing it now. I foresee a new harness in my future, or at least a new switch/wiring for that.

My question is, how do I determine what caused these wires to overheat and meld like that? Is a voltage meter in my future (hello, Harbor Freight). I don't really know how to use one, but I take direction well if anyone wants to attempt to explain how.

Are there service manuals for a 77 available online in PDF? I can find one for a 78, and suppose I could use that to get by, but if anyone knows, please help me out. I don't mind paying, but I DO hate waiting...

Thanks in advance.

 

[retiredgentleman]

Okay, update. I opened the headlight bucket this morning to find multiple wires fused together. It looks like Chernobyl in there.

The melting goes all the way to the switch at the handlebar. I'm in the process of untangling and freeing it now. I foresee a new harness in my future, or at least a new switch/wiring for that.

My question is, how do I determine what caused these wires to overheat and meld like that? Is a voltage meter in my future (hello, Harbor Freight). I don't really know how to use one, but I take direction well if anyone wants to attempt to explain how.

Are there service manuals for a 77 available online in PDF? I can find one for a 78, and suppose I could use that to get by, but if anyone knows, please help me out. I don't mind paying, but I DO hate waiting...

Thanks in advance.

The 77 year only had 1 fuse (20 amp), which makes it nice for simplicity, but makes it bad when a short circuit occurs and wire insulation starts melting. The 78 Special started using 4 fuses, which a much better design. If your bike had used a 10 amp fuse in the headlight circuit, the nasty RLU smoking/meltdown likely would not have happened.

Depending on how much damage is done, you may have to run new wires (or a new harness). You can permanently remove the RLU and join the blue/yelow to the blue/black as nj1639 mentioned.

Because the RLU smoked, that tells you where the actual problem occurred. The short circuit happened either in the headlight itself or in the wiring/connectors that feed the headlight. Yamaha only used #19 or #18 gauge wire in the headlight circuit, which is a little on the small side. I did a repair for a friend on his 1980 XS650, because his headlight wiring insulation had melted. I used #16 gauge wire to make the repair.

Check the wattage rating of your headlight bulb (sealed beam). Its wise to use a 55watt low beam, or less. I use a 40 watt halogen low beam. If a PO stuck in an extra high wattage headlight, then that could make the wiring heat up and melt.

Wiring diagrams are available for the 77 year.................there's one in the "Tech" section under electrical.

Yes, you need to get a VOM and learn to use it for testing for resistance and voltage.

If you do end up doing some rewiring, be sure to add a 10 amp fuse in the headlight circuit, and a second one in the ignition circuit as well.

Good luck.............you'll get it all sorted out.

 

[fiveohindc]

Thanks NJ and RetiredGent. I got a VOM and I'm practicing with it now. Not sure if the audible sound is a good thing or a bad thing. (can you tell how illiterate I am with electrics?) I am reading the instructions and whatnot.

I have ordered a new throttle side switch from mikes. The wiring is just too fried on the original, although I did attempt to solder in some new wires... it wasn't pretty.

The headlight looks to be of suitable wattage (40w, but the writing has nearly come off it). I do recall the hi-beam being on for a long period when I first got the bike so maybe that created the heat. I have genuine concern that I will plug in these new ones and do exactly the same thing. Hopefully I can isolate the cause. Then scrap the RLU.

I'm still unable to find this mystery fuse. I thought it should be right under right side cover, accessible in case, you know, YOU HAD TO CHANGE IT. However, perhaps the PO stuck it elsewhere? Or I am blind... ??

 

[5twins]

See that little rubber sleeve to the left of the starter relay? That's where the fuse was originally, a little plastic holder with the wired fuse and a spare next to it .....

Looks like yours has been eliminated. See that single red wire coming out of the harness with the dirty white or yellow wire spliced to it? That's where the fuse should be. It originally ran up to the positive battery terminal but yours is now connected to the starter relay. That's fine, that heavy cable it shares a connection with is from the battery positive.

 

[5twins]

Oh, here's a link for eliminating the RLU. You see what happens if you don't, lol .....

http://www.excess650.co.uk/tips & tricks.htm

 

[fiveohindc]

Well how do you like them apples? I guess I'll have to go hunting around for it somewhere under all that crap behind the battery.

Another dumb question: could this thing be running WITHOUT a fuse? No, right? That'd be ridiculous. Right???

Thanks for the link, also!

 

[retiredgentleman]

Well how do you like them apples? I guess I'll have to go hunting around for it somewhere under all that crap behind the battery.

Another dumb question: could this thing be running WITHOUT a fuse? No, right? That'd be ridiculous. Right???

Thanks for the link, also!

These bikes will run fine without a fuse, if the PO jumpered across the fuse holder. Its just not a clever thing to do, unless you like to see smoke and fire coming from your bike.

 

[fiveohindc]

Thanks guys. So far, I think I'm on my way. I got new throttle side controls to replace the burned out mess. Hooked it up and all looks good. I am going to pick up a new headlight socket though, because in looking at it, doesn't look very long for this world.

I bypassed the RLU by connecting the blue/black and the blue/yellow (and using the RLU as a coaster, currently). That works. Hi and Lo beam look good.

I'm concerned that there is no fuse on this monster. In looking at the pics I posted above, am I correct to assume that I can take that red wire (from the battery, that currently has two connectors and a random piece of wire between it) and connect an inline fuse there? I believe so but it wouldn't hurt to hear from an expert.

Also, I've got the multimeter out to test tomorrow-- how can I test if this regulator is working correctly (as in, where do I put the leads)? Sorry to sound like such a noob. I think it's prudent to make sure I'm not going to burn up more wires, blow something else, etc.

Y'all are the best. Anyone in Northern Virginia need "law enforcement" advice, I'm your gal.

 

[5twins]

Take a look at the positive battery cable MikesXS sells .....

Notice how the red wire for the fuse pigtails right off of the battery end of the cable. You hook your fuse in there and to the single red wire going into the harness.

 

[retiredgentleman]

Thanks guys. So far, I think I'm on my way. I got new throttle side controls to replace the burned out mess. Hooked it up and all looks good. I am going to pick up a new headlight socket though, because in looking at it, doesn't look very long for this world.

I bypassed the RLU by connecting the blue/black and the blue/yellow (and using the RLU as a coaster, currently). That works. Hi and Lo beam look good.

I'm concerned that there is no fuse on this monster. In looking at the pics I posted above, am I correct to assume that I can take that red wire (from the battery, that currently has two connectors and a random piece of wire between it) and connect an inline fuse there? I believe so but it wouldn't hurt to hear from an expert.

Also, I've got the multimeter out to test tomorrow-- how can I test if this regulator is working correctly (as in, where do I put the leads)? Sorry to sound like such a noob. I think it's prudent to make sure I'm not going to burn up more wires, blow something else, etc.

Y'all are the best. Anyone in Northern Virginia need "law enforcement" advice, I'm your gal.

Very simple to tell if your charging system (regulator) is working correctly. Connect your VOM directly to the battery terminals.
Engine off..........should be about 12.4 to 12.5 volts if fully charged.
Engine idling 1200 rpm (wait a few minutes after starting)..........13.3 to 13.5 volts.
Rev engine to 3000 rpm..............should be about 14.1 to 14.5 volts.