SpencerPJ

I would be somewhat comfortable soldering. If I go there, I'll ask for more advise... So, I took bike out today, gas gauge seems like it was working correctly, 1-2 bars left at 140 miles on odometer, and I get a solid 40mpg continually. It took 3.5 gallons to fill. However, I filled up, brimmed off, and not good. Gas gauge showed no bars. Put maybe 30 miles on it, started showwing full, all bars, So, I again think before I take CMS apart, I will once again, take out gas gauge (2 minute job anymore, lol) and see if the wiper etc are connecting as they should. Seems they might be very temperamental. Of course the bike is filled with gas now, and can not remove gas gauge, besides, it's smoking dang hot outside.

Post pictures if you do it. Like Snyper316 said, anythings possible.

Try this for part numbers, I've never run into your problem (yet) https://www.yamahasportsplaza.com/oemparts/#/l/yam/50042475f8700209bc787e25/1983-xvz12tk-parts

Never hurts to disconnect the battery for 5 minutes and let everything reset itself. Sometimes quirky things fix themselves.

I'm guessing pin 9 is the middle, pin 6? I zoomed in on my PC, there might be some crusty on a couple terminals. If / when I take it back out (after my check tomorrow), I will be sure to clean everything. I'll update ...

Thanks for that link Steven G. So, I investigated my Tail Lights not working. After checking electrics back there, checking both bulbs, Figured I would unplug from the CMS and start there, I noticed that the CMS unplugged fairly easily, did I not firmly seat that plug?? (NOTE: when you unplug CMS, the brake lights don't work. ) So, I sprayed with electric cleaner, plugged back to gather and voila, now the rear running lights work again. Whilst apart, I took out the gas gauge again. Manually ran it up and down, did not make any change on the CMS, acted like it wasn't even connected. Checked the ohms, and they did change on a linear fashion. SO, I'm back to only the gas gauge not working correctly, and I do feel that it is the CMS causing the issues. I plan to take apart again, and resolder as the above link suggests. And to throw another wrench into it, I took for a 50 mile ride, I'm at 100 miles on tank since fill up, gas gauge reads 3 bars. Could it be accurate? I as going to brim off again, but sure is hot outside. Sounds like a reason to go for morning ride.

Anything very slim and solid. Some say they have used plastic bottle, IMO that's getting a little too thick. Maybe even a screen protector for cellphone. As mentioned, Google it, there are a few youtube videos. But basically, slide it in, go around the whole fork. Here's one:

Update: This bike is possessed. I did get the temperature gauge working, was the loose brown wire at the sending unit (so it seems). The Gas gauge is still not correct, but that could be the mechanical slider that needs adjusted, maybe not. I will dig into that soon. My newest issue, after a 80 mile ride, the little notification for 'No Rear running lights' came on, in the cms. Both the 1157 bulbs seem good. I will dig into that. I need to scour the schematic, but first glance, could the that cms could be causing my gas gauge and now 'No rear running lights' issue? Brakes and turn signal lights work fine.

Awesome ride, enjoyed the read, thanks. I'm from Indianapolis, and was at the Dunes State Park with the TT on the southern tip of Lake Michigan 5/30-6/4. I know about the winds and chill you spoke about. Great camping though. I just gotta upgrade from my 83 (or ad to) and get out and explore the country as you did.

I clean mine it seems yearly. I use an old 35mm film negative, slides in easily, and cleans out the funkies, usually bug splat. I have never replaced either side, and both sides have leaked.

Steven: we are on the same page.. Earlier, I found the Temp sending unit, and felt the connection was not on all the way. I pushed it on. I ran bike a while and the Temp gauge did NOT fluctuate with RPM, I may have found it. I want to again get into the gas gauge and move up and down while connected to the CMS, and I will do the continuity check then as well. I went to remove gas gauge and guess who brimmed off their tank? I need to burn a gallon of gas before I can remove my gauge, and rain is nearby. I will hopefully get this done tomorrow and report back. Thanks for helping

First off, I have seen posts over the years that Skydoc17 sells the perfect set-up. I agree with luvmy40. I like this link to get part numbers, then scour the interweb for deals https://www.yamahasportsplaza.com/oemparts/#/l/yam/50042475f8700209bc787e25/1983-xvz12tk-parts

Voltage reading with ignition on, Battery alone, both sides of all fuses, really the same, 12.2 volts, including #4 , the brown line. That's just sitting, not running. Damaged after fall, left rear turn, left fairing a bit. I have dug into those sides extensively, unplugged this and that, especially anything related to 'brown wire', can not make any change in readings. After chasing the schematic, seems brown also connects into rectifier? I don't seem to have charging issues, but I guess I'll go find that and at least inspect plug. Any other ideas?

All my boards appear spotless clean.And what would explain the fact I can plug only the CMS module in and it acts up, OR i can plug only the dash / temp gauge in, and it acts up?

As Freebird suggested, I did a complete inspection and electrical check of my fusebox area, and everything seems solid. Voltage seemed correct, I wiggled everything and no changes with the meter. Although an upgrade is a good idea, it just doesn't seem to be the culprit of my problems. I completely dismantled my dash, and what I have concluded, even with everything removed and un-plugged, I plugged only the CMS in, and gas gauge still did not work correctly. Because I also have issues with the temp gauge fluctuating with the change in rpm (sometimes), I just don't see how the dash or cms are my problems. I ran several temporary ground wires thinking that it could be a glitchy ground? Can anyone point me in a direction to investigate next?

So I started to tinker with my issue..s I got the bike looking like Frankenstein. I unplugged the CMS, took for ride, and the temp gauge still responded to the throttle / tach, so something not right (maybe a ground issue?). I then was at a stop light, wiggled the main positive wire fuse area, and bike died. Pushed to side of road, and it refired, and rode on. A mile down the road, I pulled over to plug cms back in. gas gauge still not accurate, reading 2 bars so maybe accurate?. Being at 150 miles, I stopped and filled up. (took 3.6 gals to fill almost to brim) THEN, stupid bike would not start, NOTHING, dead. I pushed to side of station, bam, fired up. I do not remember now if the lights were on dash when dead or not. The gas gauge now reads empty, and red light blinking (with a full tank). I drove it home, and today, I plan to start at battery connections, and go through everything electrical related, and take the dash out if need to. Rain is in the forecast all day, so we will see. Any or all ideas are welcome... I'm not super great with electrical. thanks

I loved the bike parade, to funny. Crazy place.

I kinda feel the same way. I have not gotten into cms or back of dash, lots going on, kids in town, etc. House empty next week, I will see. All I know, I slightly wiggled the big connector, things are acting strange ever since. Here's one for you, the temp gauge changes with the rpm, like the tach is somehow bleeding into it. It sure seems that I have some loose connections or loose solder joints after the 'great fall'. It ran home missing, and acting like the fuel filter was clogged, and it's not, I have a glass one, clean and full as it should be.

so i took a stick and lightly wiggled the back of the main connector, and now the bike is running crazy. Temp gauge is acting up, motor cutting in and out. I limped it home, and after it cools off, I plan to get into the CMS area, and do better investigating. Anyone have a quick link on how best to get behind the dash?

I would tape over the blinking red light, but the fuel gauge is kinda important. I know I could always refuel at 200 miles and be pretty good, just miss it being accurate. I will begin messing with connector as Snyper suggests.

A couple weeks ago, my 83 kickstand broke and left by bike on it's side in the driveway. Ever since, the fuel gauge has acted erratic. Never reading correct. I have searched this forum, taken the sending unit out twice, and still, no luck. The sending unit has been cleaned, the wiper works well, I get a nice change in ohms from empty to full, so I think that is ok. Do you think something came loose in the electronics on the handlebars, I think they are called the cms?

I pay at the pump. I like to use Credit Card, you are not liable for fraud. I hate debit cards where the money comes directly from the bank account. Much more hassle to get your spendable money back.

I do exact same thing, but drilled a couple holes in my plastic for better look. I carry a few in my glovebox as well.

Great Pics. Hope you have a dry weekend, raining here in Indy. I did get out for a 3 hr ride yesterday, burned up the winter fuel.

Me too, I just click 'new posts'.