electrical troubles

[greatwhiteshark]

I have some troubles with the electrical system on my bike which is a 1980 xs1100 special . I just bought the bike a few months ago and the signals and headlight seem to work sometimes and then other times not , this is what happens the headlight will not come on until the bike is actually running and the signals will come on when the bike is not running but will not blink, when the bike is started they will blink most of the time I figured out from reading this forum that it was probably corrosion in one of the plugs throughout the wiring harness or maybe in the handlebar switch I managed to find another handlebar switch at my local salvage yard but after installing it there was no difference . I have gone through many of the wiring plugs and sprayed them with electrical cleaner and worked them with a little brush but I have not come across any serious corrosion and since doing this there has been no change . The other thing is the p.o. had the fuse box rigged up and a couple of fuse wires were stuck together with no fuse there so I am wondering if this could have any bearing on the lighting problem . Also I am about to put in a new fuse box but I don't know which size of fuses goes in which spot . sorry to go on for so long ....but any help would be really appreciated ......thanks.........mark

[Ken Talbot]

Welcome to the world of 20+ year old motorcycle electrics. It sounds like you are well on your way to sorting out your problems, but you've still got a few more connections to clean. Your headlight is supposed to work the way it is - it is not supposed to come on until the motor starts. This gives more juice to the starter. Signals that don't flash is also pretty common until the motor is running a bit above normal idle. This is just a voltage problem that will go away once the entire electrical system is clean, and as long as your battery has a decent charge. You will find that start and stop city driving will draw the battery down and the signals will stop flashing at idle. Again, this is normal because of the way the charging system was designed. Check out the various electrical articles in the maintenance, repair, and modifications sections of the forum for more.

BTW - have you run into any of the other XSives in your neck of the woods? There's actually quite a contingent on the island.....

[TopCatGr58]

Hey there GreatWhiteShark,

If you will go to the Links section, you'll find a link for an owner's manual for the 81 H/SH, but it should work well for your 80 as well, that's when Yamaha changed the design from the 78-79 series. It's about 6MB PDF file, just download it and you'll have your info about the fuses and other basic maintanence stuff until you can get a repair manual.

The grounding straps for the rear lights are connected to rings that are part of the light mounts, on the inside of the rear fender, and lots of corrosion/rust can form there. Poor grounding is another reason for turn signals not working well. You may want to unbolt them and check and clean those contacts as well as the other connectors and fuse block and such. Keep at it, you'll get it working fine in no time!!! Welcome!

[greatwhiteshark]

thanks for the info I did end up finding the problem with the signals it was a combination of a corroded handlebar switch and a faulty flasher unit the signals now work great even when the bike is not running.....thanks again guys...mark

[markb80]

electrical problems

I have the same problem with turn signals not always flashing at idle. The bike needs to be revved up a little to make them flash.
I have also noticed that the voltage at the battery drops to about 12 volts at idle. This seems too low. I did the ohmmeter tests in clymer manual, and both the stator and the reg/rectifier check out ok. The resistance on the stator was .7 ohms instead of .5 though, but no shorts. Are the tests in the clymer manual adequate? I cleaned the contacts at one of the 2 stator connectors, no improvement. The other didn't look bad. I will check taillight ground. Is it possible that the field coil is given to weak of a command by regulator due to ground issues? Maybe the regulator is not commanding the right field coil current due to aging of electronics. If that were the case, I wouldn't think that revving engine up would fix problem. Maybe its the .7 ohm reading at the stator. Not sure. Next I may try to monitor the field voltage/current at idle and when revved up. If the field increases, then the regulator is not commanding enough current to stator. If the field current does not change (it shouldn't), then the stator just isn't putting out enough current. It is possible that the stator isn't grounded well enough. Any ideas??????

[markb80]

One correction to my previous reply. I believe the field current should drop as RPM increases to regulate the stator output voltage. This forms a feedback control loop. I will have to look at some alternator theory to be sure that the RMS alternator voltage is proportional to the RPM and the field (excitation) current. If this is correct, the control loop formed by the regulator/rectifier and the stator should have gradually decreasing field current as the RPM increases. If so, this means the field current at idle is at its maximum value. If the maximum current capable of a reg/rec gets lower with aging electronics, then maybe the reg/rec just can't deliver enough field current at idle..... Or maybe I just have grounding issues.

[young nip]

flasher at idle

Great white,
I have a little problem with mine too at idle.i can sit ata light and blip the throttle to make mine flash, Ive cleaned and dialectric greased every connector in the flasher signal line and every other one on the bike plus repalced fuse box too.( amzing what a litlle sand paper can do), still if mine idles at 1000 the left flasher is tardy some days.weak wire some where ?perhaps. I fiddled alittle and found if i adjusted my idle to about 1200 rpm( after warm up) my flashers will work fine at idle and that rpms not too high. Has something to do with the voltage Ive read.(beyond me).I dont have to do stop and go city,( hot bike ,weak flashers) luckily,Im a small town guy and Im on alot of open county roads. Hey these flashers are nature of theold beast. The 1100's still do the best of everything a bike can do regardless. Havent seen to many 25 yearold bikes around that do what these bikes still do.gotta live with and adjust to the quirks.
good luck
Steve

[greatwhiteshark]

Hey Y N I'm not much for working on electrical systems but I did manage to get mine working great again . I'm just wondering if you had a look at the handlebar switch itself I know mine was pretty bad inside you can take the whole thing inside apart and clean parts. I ended up having to replace a switch inside and luckily my local salvage yard had the parts I needed......good luck....mark

[markb80]

Did the switch cause your battery voltage to read low? I need to look at schematics, but I guess it is possible a voltage drop at a switch to cause the regulator to measure a higher voltage than is actually getting to the battery. What would have to happen there is that the battery gets 12 volts and the switch gets 1 volt, so the regulator doesn't try to push more field current to the stator field input.

I learned all about bike electrics from fixing an old yamaha RD350, the previous owner shorted the field winding to ground by re-attaching wires wrong after putting in new points. The manual didn't show how it should be connected, so I had to figure out the theory of operation. Amazingly, the original reg/rec wouldn't blow with the incorrect wiring, but a new solid state unit melted. The old unit was probably ok, but bike wasn't charging with the field shorted to ground. The stator checked ok, so I thought it was the regulator, turned out to be incorrect wiring.

Thanks for response.

[markb80]

charging system

I looked at schematic. The brown/tan wire on the reg/rec is the sense (voltage measurement) wire. The green wire is the field current to the alternator. The field current is like a valve allowing the alternator to put out higher AC voltage (and current). The higher the AC voltage, the higher the rectified AC voltage. Since the tan wire (sense) is measuring voltage after the switch voltage drops (2 V typically), the controlled voltage is the actual voltage to the battery (after the switch drops). This is assuming no voltage drop across the fuse to the battery.

The manual says at idle the rectified voltage output is about 14-15 volts. However, there is at least 1.8 (probably higher) volt switch drop. This leaves between 12 and 13 volts for the battery. This charging system will keep the battery charged marginally at idle. I have seen other bikes that will put 13 volts to the battery at idle. So an XS11 must be ridden to really charge the battery.

Back to the turn signals. I think the cleaning of grounds will hopefully solve my problem. But I think the flasher unit may be barely functional at idle due to the marginal 12 V output.

It is possible that a more modern regulator will push more current to the field input of the alternator and bring up the voltage at idle. The new unit I put on my rd350 worked great. The headlight stayed bright at idle and tue turn signals blinked quickly. I will post the manufacturer (can't remember name). It was a universal 8 wire and may work on xs11 also. Newtronics of England makes a good one too. They run around $100.

[markb80]

A couple more questions/suggestions.

For greatwhiteshark - What does your battery voltage read while idling? My xs1100 charges well and runs well, but at idle I only get 12 volts, which I know is not ideal and will run the battery down if I idle too long. The bike may work fine with low voltage at idle, but its kind of hard on the battery in the long run. Youngnip's bike is working fine, but his charging system is marginal like mine at idle.

I think these bikes probably had more like 13 volts originally at idle. High resistance in the switches can't cause this issue because the sense wire of the regulator reads the voltage after the switch drops, with respect to ground.

There are two likely possible causes. First the regulator's field output (green wire) has a weakened output stage transistor due to age. The regulator is putting out its max field current at idle, but it isn't enough to make the alternator produce the 13 volts (across the battery) that the control loop is trying maintain. A new regulator can fix this. I bought one from www.partsnmoreonline.com that made my RD350 crank out 13+ volts at idle, it works great, but you have to modify mounting a little. Newtronics makes one, but I think the size and mounting holes won't work out as well as the one I bought from partsnmore.

The other possibility is that the permanent magnet(s) in the alternator just ain't what they used to be. I will look at manual to see if it can be disassembled. If I can find out the magnet(s) spec in Gauss, I can measure it at work and see what mine reads. If its the magnet, there are two ways to fix the issue. First is to replace or remagnetize the magnet(s). The second is to compensate with more field current at idle. A more modern reg/rec with higher output current capability would probably fix this too. It's possible that my RD350 had a weak magnet(s), and the new reg/rec compensated for this.

These bikes are still great, but if the charging system continues to deteriorate we're all gonna have problems.

[Geezer]

I'm working on a replacement rectifier/regulator unit for the XS11. I have a rectifier that I’m more than satisfied with (55 amps) but I’m working on a regulator that is small enough so the completed package will fit in the same place. I’ll let ya’ll know when it’s finished.

I want to run it on my bike before for a while before I sell any of them. Mine won’t be so over priced and under guaranteed as the ones from parts & more.

http://mysite.verizon.net/res1fbiq/

Geezer

[fusionking]

Way to go Geez!! Looks like a bright future for your project!

[MartyA]

You guys are too cllo. Me and electricity never make a connection. Keep at it.

[markb80]

Sound good Geezer. Do you agree with my explanation of the operation of the voltage regulator/rectifier? Please correct anything that is not 100% correct. I'm an electrical engineer, but motors/alternators are not my specialty. I wouldn't mind testing one of these out in the lab.

When you say 55 Amps, do you mean the regulator field current output will make the alternator produce 55 Amps? Is this dependent on the condition of the alternator/magnet(s)? I know the newer units have more field drive capability, but I will have to find out the capability of the original vs the new ones.