1981 XS1100 Midnight Special Slow restoration

[Medumdum]

Guess I’ll take a look at those valves first then. I’ll need to go grab a set of feeler gauges tomorrow morning. If I need to replace the shims, is there any way to remove them besides using the special tool? Cheapest one I see are around $100, and that feels like a lot of money for a small hunk of metal.

[DiverRay]

So work on the carbs, but don't forget, you need to adjust the mixture for EACH carb, one at a time, and THEN set idle to about 1000, and sync all 4 carbs with a set of gauges. This is AFTER you have checked the valve clearance. Yes, it all rolls up into one long process, but the bike will run smooth if done correctly.

[Medumdum]

Took a bit more going through the carbs, but now it’s finally running on all 4 cylinders. It revs good, but feels like it’s running lean at idle, so now it’s just a matter of getting the carbs dialed in. Forgot to say I found another tested TCI, that came in about a week and a half ago, so ignition problems have been fixed now.

[cajun31]

here is the other one that they state has not been tested. 1980 Yamaha XS1100 Y860) CDI igniter ignition control unit box | eBay

[cajun31]

So, I dunno why the first time I plugged in the replacement TCI I still got no spark on 2-3, but today I went out and plugged it in and it was magically working. I’m finally getting strong spark on all 4 cylinders. Going to try and see if soldering the pin on the original TCI fixes it, but I’m also looking for a known good replacement one if anybody has one. I can’t find that one on eBay anymore.

Better jump on this. They are getting hard to find. 1981 Yamaha XS1100 XS11 Midnight Special Ignition Unit TCI / CDI TID14-04 4R0-10 | eBay

[Medumdum]

So, I dunno why the first time I plugged in the replacement TCI I still got no spark on 2-3, but today I went out and plugged it in and it was magically working. I’m finally getting strong spark on all 4 cylinders. Going to try and see if soldering the pin on the original TCI fixes it, but I’m also looking for a known good replacement one if anybody has one. I can’t find that one on eBay anymore.

[LAB3]

You should have two wires with rings on them that are grounded to the frame using one of the bolts holding the regulator. Just for good measure it's wise to pull that bolt and clean up the rings and mating surface.

Sounds to me like you have an issue where either the wiring to the coil or the coil itself is bad. If you're sure that you have power to the coil on the positive side you probably want to check if you have continuity from the ground side of that coil back to the TCI. The TCI fires by completing the electrical path on the ground side, not by applying power to the positive side.

[Medumdum]

Yeah, unfortunately that bike was an 80, so it had the older TCI. I hooked it up to see if I would get spark on 2-3 finally, but no still no spark on the 2-3 ignition coil. If I swap the leads and plug the 2-3 coil into the 1-4 plug, the coil fires fine. Tested with a fully charged battery. I really doubt this other TCI is broken in the exact same manner as the first one, so I’m starting to feel a bit clueless. I cleaned up the main battery ground, is there any other grounds I should try and clean up?

[cajun31]

I’ll have to double check when I go pick it up, since the PO had listed this one as a 1980, but it’s definitely an 81. If it does turn out to be a dud or incompatible I’ll pick that one up, hopefully it’s still there. Even if it’s an 80, would it be compatible enough to verify that I get spark on 2-3 with that TCI to 100% verify that’s the issue?

The difference between the two years had more to do with the vacuum advance then the problem you are trying to diagnose. You should be able to figure out quite quickly if your original is bad by hooking the other up. Just don't go overboard with the throttle while trying it. The problem with this new forum, although much appreciated, is the fact that when you do a search on this site it brings you to a multitude of threads that members have posted invaluable info with references to pictures that no longer exist on photobucket and links back to the .com site. The info is still good to a point, but without being able to reference the pictures and the original threads it makes it more difficult to research things. What you can do is do a search on TDI differences and it will bring up a lot of info that you can read through. You will find many that reference the same problem you are experiencing now. Might be helpful.

[Medumdum]

I’ll have to double check when I go pick it up, since the PO had listed this one as a 1980, but it’s definitely an 81. If it does turn out to be a dud or incompatible I’ll pick that one up, hopefully it’s still there. Even if it’s an 80, would it be compatible enough to verify that I get spark on 2-3 with that TCI to 100% verify that’s the issue?

[cajun31]

I am assuming that the parts bike you are getting is also a 1981 year model? The reason I ask is because the TCI from previous years will not work on the 1981. It was changed for 1981 and should have a yellow tag on it with 4RO-10. The previous years TCI will be labeled 2H7-10. Bob or RangerXS1100 has one you need for sale on ebay. The reason I point you to his should you need another is because he has tested it to make sure it is good. There is another one but they specifically state they do not test parts for sale.

[Medumdum]

Dang, I’d head rebuilding some other TCIs wasn’t too difficult. Guess I’ll update y’all in a week or so once I grab that parts bike.

[DEEBS11]

I had one of these apart a few month ago and everything inside is coated. Not really serviceable with standard solder equipment. You really need professional tech equipment & conformal coating removal equipment. You should just delicately touch up the solder on the plated through holes shown in the picture without overheating the joint. Opening that unit up will give a high degree of incurring more issues. The problem is more than likely in your ignition sensors or harness as this is a more common problem. Problems with the TCI are very rare with the exception of cold/cracked solder joints. A non-invasive way to test this is to plug in your second spare TCI from the parts bike and see what happens. No risk of further damage in that test.

I re-read this thread and you did measure 735 ohms at the sensors which is good.

[Medumdum]

I assume I test that just by touching the joint and the pin with the multimeter leads set on continuity? They all beep, and read 0.0 ohms. Checked the other connector and those are all also good. I’m out of flux so picking some of that up, cuz I’m assuming I have to desolder the pins to the the board out of the actual case to look for any broken caps.

[DEEBS11]