Finally riding my XS400, but still not ready for the road?!?

[markjs]

Well it is kind of frustrating don't you think? I don't know what you mean by insulting you? That was certainly not my intent. More than anything it's that I absolutely need cheaper transpo and this has been a complete waste of time, energy, and money very likely, and I have less than nothing to show for it, and if it is the CDI, that is certainly the case. I do have issue with these things always being such a weak point, and that unless you gamble on a used part, the bike is toast. If indeed it is the CDI, then for all intents and purposes, it is a POS to me anyway, being as there is no way for me to fix it if so.

Unfortunately I am 99.0% sure it is the CDI; I can't for the life of me see what else it could be, but I will go over the wiring again tomorrow before I totally give up I guess. Is there any other likely possibility?

Thing is though, if it was a Honda, even if it was the CDI there might be hope, but these bikes are hard to find at best and I can't take the kind of $150 risk on a part that will just as likely be DOA when there is no way to test it.

 

[16VGTIDave]

<Angry Dad voice>Of course it is frustrating. Did you really think that buying a 30+ year old bike would be without challenges? Man up.</Angry Dad voice>

Every time you call your XS400 a POS, it reflects on all our bikes. If you actually want some more help from the people here, you'd best drop the attitude. We are a helpful group and will try to assist you as best we can, if you want the help. If you just want to moan and complain, we have our limits... Clear?

Now, take the time to read the service manual and go through the testing procedures. Give us the specifics of your bike (a signature line is a great way to remind us what you ride), tell us what you have done and what you have found. Don't jump to conclusions, ask questions. You can't be the first person to have encountered this issue.

Have you tested the pick-up coils yet? Have you checked the wiring for bad connections or broken insulation? As a last resort, the TCI module (NOT a CDI) can be rebuilt. Anyone with basic electronics skills (mainly soldering) can do it. It is 1980's technology, not 2012 technology.

Dave

 

[markjs]

OK, I apologize, it's just I was so close and now it seems as if I am miles away from even hope now, I got to admit I am pretty down about it.

Anyway, I am looking at the wiring tomorrow but I am not too hopeful, a previous owner put some extra lights on and the headlight isn't stock, but even so I can't find anything that looks suspect and I have done quite a bit of looking.

Still though what you say may be something, because as far as I've heard, a TCI will either work or not, not sort of work, so that might mean there is something being overlooked, maybe a place where the connection is just too weak. I have not tested the pickup coils, I guess that's tomorrow.

It's really hard not to be depressed about this though. I am so broke and my car and gas prices are killing me and it seemed like I was so close, and now, the only TCI unit I can find is new but is over $400. I can't solder either, I have a friend who maybe can, but I have just never been able to do it worth a damn, so with his help possibly it can be repaired, but unfortunately that work will probably always be beyond me (not steady hands among other things). The other possibility, is I see some 4 cylinder models had units that have the same plugin. Any possibility one of these ones would work? Most of them are outrageously expensive (even on eBay) but a few were under $100, and as I said, they look the same, have the same plugins (not that that means it will work though I know).

 

[16VGTIDave]

Leave the TCI as the last resort. There are many other things that could be causing problems. And you would have to get a module with the same part number, even if it is for a different bike. The connectors are only part of it. The module also does timing advance.

Anyway, how did you determine that you are loosing spark on one cylinder? You could be chasing after the wrong thing.

 

[markjs]

Because it runs on two up to a point but then a total loss of power. So what I did was pull the right wire off, put the old plug in it, held it to the head with insulated channel locks (no wish to get shocked), and then started it running on just the left cylinder. As long as it is at idle or up to around 2000-2500RPM, the spark is nice and healthy, but as soon as the revs get any higher the spark disappears completely and there is no spark at all till it goes back to that 2K-2.5k RPM or under, then spark resumes and once again looks healthy.

I did test the coils like I said, they were not spec but the temperature was considerably colder than what the book called for and they both measured identical resistance, so I assume they are fine.

 

[markjs]

Oh and as well, the carbs are fine. I have done millions of carbs it seems and these started off quite clean (comparitively) plus I did a thorough job, even stripping them completely down, the juts got a good soak in carb cleaner, the bodies got boiled in vinegar and water, and it all got blown out. The slides and diaphragms looked very good as well.

I've revived quite a few old yard finds (admittedly mostly Honda just because there are so many), and as carbs go, these are in quite good shape. I've got TONS of carburetor experience, it's this electrical stuff that always befuddles me, the mechanical and fuel delivery has always been the easy part for me.

 

[TimmyT]

sorry to wake the dead here but we all have our own sob story I have 2 kids and got laid off at the beginning of the week, times are tight and everyone is broke unlucky ones are poor. I have had my bike for 2 years and hopefully by the end of the weekend I will hear it finally run for the first time. Be glad you have 2.5k revs to sort your problem I am blind and dumb here man. $400 for the bike 1000 unpaid hours working on it and maybe a couple grand acquired in parts, tools and supplies combined. Im doing it just for the hell of it and hell I know Im not alone cause I would have never started it without a site like this. ... Also if you go to a wrecking yard and there is 10 ton of Honda to grab parts off of then why would you think these bikes are the POS? I say you have come far to isolate the issue without getting bit by your battery amperage, you are not dead man so dont roll over yet! I came across this thread way to late. Soldering supplies $25.... TCI $125 .....TCI and soldering supplies $150. 2x working TCI value after soldering $250. New skill aquired...priceless.