Known good test for a TCI box?

SClay · Full Member Joined: May 30, 2008 Posts: 93

Here's the skinny. While I do eventually want to switch to points, I hate being defeated by things, so I still want to get the bike running on this ignition system(81 Special).

I Need to know if there is an actual test for the box. I did the transistor test, and it came up bad, I changed that out. Went through the solder connections on the board, all are solid, redid a few just for good measure. I am getting juice into the box(red/white wire). My coil is good, and almost brand new I might as, the high performance one from MikesXS. Along with new wires, caps, plugs, all that. Went through the ignition/start related connectors on the bike, cleaned, re-soldered, the whole nine. Pickup coil is good per resistance test.

So here is a bit of background. About 3 months ago, went on an awesome ride out to the coast, ran great, the whole time, through the heat, then through the rain, it was a hoot. Get home, park her, don't have a chance to ride again for about a week. Get back on it, won't start. Weird. Fiddle with it a bit, it starts, runs ok, but then shuts off. No matter how much throttle I feed into it, it just shuts right off, and will start again in a few minutes, but will repeat the same acts. Sure, petcock is clogged, nope, cleaned that. Went through the carbs again(Mikuni round slides Rolling Eyes

). Nothing. Pretty much let it be for a bit whilst I put my other bike back together. I was getting stressed over the XS, and I just went back to my caveman points on the Honda.

Well fast forward to about a week ago, Honda is done, again, and I'm looking to get the Yamaha at least running before I strip it down. I feel it's only fair, and it will give me some motivation to finish it. Fiddle a bit, nothing, won't start. Pull the plugs, check the spark, it's there, not great, but it's there. Charge the battery overnight, try again, same. This is about when I started looking into the box, replacing the transistor, checking the joints, doing all the connections on the machine, checking the pick-up coil. After reassembly, it sparked a few times. Now, nothing. No spark, at all. Still getting power in all the right places, everything still checks out, but just nothing. This is a huge bummer. I don't consider myself an expert, but I've worked on enough cars, and enough bikes, to know my way around one of these things. But this is just beyond me. Do I want to buy another box? Heck no. I'll go with a PamcoPete setup before that. But I hate losing to something like this, just stressful and frustrating.

So here is what I am wondering, is there a way, or perhaps, another way, to test the box itself? And to see if it is getting a signal from the pick coil? And coincidently, that it is SENDING a signal out to the coil? Or are the readings so minute that I wouldn't be able to pick them up at the rate they are happening without a scope?

By the way, everything on the machine, electrically related, works perfect, just to clarify, don't want you all thinking it is some 'pulled out of a ditch and why won't it run' kind of story Very Happy

, it seems the ignition system is the chink in the armor here.

Thanks for any help you can send my way.

Steve

P.S. Shameless plug of my other bike because I am in love with it:

Retiredgentleman

Seems that you have tested everything. Have you measured for voltage at the red/white connections on the coil and on the TCI unit. That would be a check to see that the ignition switch and kill switch do not have excessive voltage drop due to corrosion on contacts.

xsjohn

Steve.........check the magnet on the rotor......probably not the problem but I did hear of a case where the owner had spark problems and swore he fixed it .....and it was the magnet being a bit too weak.......sounded doubtfull to me then but easy enough to check........they aren't terribly strong to begin with so remagnetizing it could be possible....like a guitar pickup it requires the magnet to create a voltage....sorry if this is all BS....

Read this on Google........
Simply "recharge" your magnet by matching up opposite poles with (N to S and S to N). When the poles attract, the superior magnetism from the stronger magnet can rejuvenates the weaker magnet.....??????

xsjohn

SClay · Full Member Joined: May 30, 2008 Posts: 93

Retiredgentleman wrote:

Seems that you have tested everything. Have you measured for voltage at the red/white connections on the coil and on the TCI unit. That would be a check to see that the ignition switch and kill switch do not have excessive voltage drop due to corrosion on contacts.

Yes sorry I didn't put that in there. Both read the same as the battery voltage, about 12.3v. So I think I'm ok there.

But John, what exactly are you talking about with the magnet on the rotor? I read elsewhere to check that, and I pulled the cover, and it really doesn't 'feel' very magnetized, but you mentioned it is a very weak field. Is there a definitive test I can do to verify it's workings. Or perhaps I'm just not quite understanding how the system works, which is a distinct possibility. And for reference, when I pulled the cover off, I touched the screwdriver I used against the rotor face, and there is no noticeable magnetism. Would this be where I would be testing the field? And I can rightfully assume that my rotor could very well be toast. Thoughts John?

Steve

xsjohn

THere is a magnet on the outside edge of the rotor face..... maybe a quarter of an inch......think it is magnetic material impregnated in some kind of epoxy.....as the magnet crosses the pickup coil it creates a voltage that triggers the TCI.........there is 2 coils in the pickup coil.....some how the differential creates the advance........not sure how that goes cause I am a part swapper..........look around the edge you wil see it...........

xsjohn

SClay · Full Member Joined: May 30, 2008 Posts: 93

Ok just read a quick blurb on testing the rotor. Turns out I have to have the key in the 'on' position right? I'm not sure if I had tested it this way, I will for sure do so when I first get the chance...that does sound correct right?

Steve

xsjohn

Test the rotor.........lift at least one brush or remove the stator........should be 5 or more ohms between the two brass rings and infinity from the brass rings to the base of the rotor (steel which is ground)....infinity test tells if winding is grounded to rotor body.........

xsjohn

SClay · Full Member Joined: May 30, 2008 Posts: 93

Ok John, sorry for the delay. But just finished testing the rotor, checks out just fine. I also have just a bit of magnetism with the key on, which I believe is correct. Any other spots to check? It seems weird with the amount of issues we have with these TCI boxes, there is no real test besides the transistor one..

Steve

xsjohn

SClay........here is the magnet I was talking about.....might want to find a second tci box.......that is the best test for them that I know of........

xsjohn

SClay · Full Member Joined: May 30, 2008 Posts: 93

Ok, I've got spark again. But it unfortunately will not start still. Not sure why. I don't suppose anyone has a procedure to check timing on these things without them running do they? I just don't want to be chasing my tail if something is internally wrong with the chip in the TCI box.

With points, one can obviously just line up timing marks and bam, you get the information you need with just figuring when the points are opening..but not so on this beasty.

I occasionally get a ridiculously loud backfire out the exhaust as well, that's why I am now looking at timing. But, the engine has never been opened, it ran perfect before(as mentioned above), and I deep down inside I just don't think there is any mechanical timing issues...

Steve

pumps

I'm listening...and reading. I have points so I can only relate to the frustration part on other issues. I don't know enough about the TCI boxes.

I do want to say that I appreciate the work you've put into the Honda. Looks very cool.

Retiredgentleman

As per my previous post, I think you should measure the voltage at the red/white wire connection at both the TCI unit and at the coil, while you are cranking the engine with the starter motor. Actually, just measuring at one location will be good as the wiring is a common point. Post back with the voltage you measure.

SClay · Full Member Joined: May 30, 2008 Posts: 93

alright guys, just checked it, posting from my phone, while cranking, it shows a little over seven volts. Now keep in mind I am still getting spark at this point, but could the low voltafe cause a timing error? The battery shows a little over twelve unloaded, but I suppose the battery vould be toast, vould it truly be causing erraticall timed spark? By the way, sorry for any spelling/grammar errors, the phone's keyboard is very small.

Steve

Retiredgentleman

Bingo, the low voltage is your problem. TCI ignitions don't operate well with low voltage. Either your battery is worn out, or you have a high voltage drop as current flows from battery to TCI and coil. Check main fuse,ignition fuse, ignition switch and kill switch for corrosion/dirty contacts that cause high resistance.You probably need 11.5 volts or more at the TCI and coil in order to start the engine.

SClay · Full Member Joined: May 30, 2008 Posts: 93

So I just finished jumping the XS off of the BMW's car battery. To no avail. While cranking, the voltage but dropped to 12.5, and still nothing. I am getting good spark, verified. I am receiving fuel, as evident by the gun-shot like backfires, and the wet carb throats and intake tract. Just can't nab this one guys. I know my questions are becoming tiresome, but any other ideas? The contacts on all the terminals look good, I've already gone through and cleaned the ones on the TCI and coil plug, as well as just today did the ones on the ignition switch. I may just give it up and get myself onto a points setup, not sure why I can't get this girl to run...

Steve

xsjohn

Have you had the rotor off.........could it have sheared a key and got the rotor off ......could look in the plug hole and see when the piston is on top and rotor mark is on the T..............?????????

xsjohn

Retiredgentleman

To continue on the "timing" theme. OK so the engine won't run, but maybe your timing light will work when the engine is just cranking. Does it fire when rotor is in the "F" area?

SClay · Full Member Joined: May 30, 2008 Posts: 93

Retiredgentleman wrote:

To continue on the "timing" theme. OK so the engine won't run, but maybe your timing light will work when the engine is just cranking. Does it fire when rotor is in the "F" area?

I'll have to check on both accounts. It should work whilst cranking, at least if it's being jumped off the car battery. I'll have to take a peak at it today. During start up, on these TCI rigs, is there any automatic timing advance/retard?

Steve

xsjohn

Starts out retarded and starts moving up about 2000..............xsjohn

BCrider

SClay

I just went through three weeks of tracking down no-start / no-spark / weak spark weirdness that cleared up only after replacing the TCI box (and a dead coil which I think was taken out the by the failing TCI).

Here's another test for the TCI box: jump a test light from the orange terminal on the coil to ground, turn on ignition and light should come on; crank engine and, if TCI is good, test light should flicker off with pulse from TCI, if test light stays on TCI is bad.

I'm convinced now that the TCI can malfunction in many ways resulting in weird and frustrating symptoms. I agree with xsjohn that the best thing to do if possible would be hook up another one and see what happens.

Here's a link to the sequence of things I did over the past 3 weeks:

xs650temp.proboards29....read=10600

Good luck...

SClay · Full Member Joined: May 30, 2008 Posts: 93

Quick question for ya guys, are all the boxes the same? Found a few, but with slightly different part numbers. I believe I read somewhere all the six pin boxes operate the same..true?

Steve

BCrider

According to other posts on this site, the TCIs are interchangeable.

SClay · Full Member Joined: May 30, 2008 Posts: 93

Good to hear. I broke down and bought one. There are actually a few on eBay right now under the 100$ mark. This one I picked up for 50 bones. Not bad considering the price I've seen on some. I think once I get this one, see if it works. I am going to reverse engineer the factory unit, see if I can come up with something a little bit more reliable.

Steve

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Yamaha xs650