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TCI questions

Discussion in 'The Garage' started by 2005c50, Aug 3, 2015.

  1. 2005c50

    2005c50 XS400 Member

    My name is Paul and this is my first post. I've been riding (legally) for 45 years and working on bikes longer. I currently own 9 bikes of varied breed, but my current project is a 1980 XS400. My concern is an intermittent off idle miss that occurs after 5 minutes of run time and progressively gets worse as the engine heats up. The bike starts on the first kick and after running on choke for a short time will idle and accelerate smoothly, but the warmer it gets, the more often it will misfire. If I run it long enough and shut it off, it will not restart until it cools down.

    Here's what I've done so far:
    Carbs cleaned and all passages checked for unrestricted flow
    Diaphrams good and slides operate smoothly
    Carbs synced to within .5 inch of vacuum
    Carb boots sealed and leak checked on carbs and head
    The misfire has been verified as electrical using inductive timing lights on high tension leads............ (continued)
  2. 2005c50

    2005c50 XS400 Member

    ....The coil resistance is within spec when tested cold (70 degrees) and hot (120 degrees)
    The coils were swapped side to side and the miss stayed on the same connector (red/white and gray wires)
    The pickup resistance was tested cold and warm and are within published specs (700+/-150)
    Connectors and grounds cleaned and tight.

    Now to my question. Has anyone had a similar concern and found it to be caused by a failing TCI. I feel that I've tested/eliminated everything else, but I haven't opened up the box to check for poor solder joints or corroded/overheated components.

    Thanks for reading along this far and please forgive me for such a long post. Any input would be appreciated.

    I searched the subject and was unable to find my exact problem.

  3. 16VGTIDave

    16VGTIDave XS400 Guru Top Contributor

    Hi Paul!

    Sounds like you have done all the hard work already, and know the answer to your question. When my TCI module failed, it had been warning me by misfiring at higher RPM's. I mistook this as carb/jetting issues. Then the module finally and completely crapped out 2.5 hours into a 4.5 hr ride. A trailer ride home and a replacement module had my bike running again.

    I'd suggest sourcing another module now, and the trying to repair yours when convenient.

  4. 2005c50

    2005c50 XS400 Member

    Thank you for the reply Dave. Today I took the cover off of the TCI and from what I see there is no sign of overheated/burned components or corroded solder joints. Just for information sake, I found out that the left cylinder is controlled by the pickup sensor that is at the 12 o'clock position and the right cylinder is controlled by the sensor mounted at 9 o'clock. I think that I've exhausted everything else so I'll start the hunt for a TCI. I'm not very enthusiastic about buying used electronic parts, but that seems to be the only reasonable choice.

  5. BBS360

    BBS360 XS400 Guru Top Contributor

    I don't think I've ever seen anything mentioned before, but is there something that would replace the tci unit?
    Pamco Pete's unit is close but doesn't do the advancing.

    It'd be difficult to reverse engineer but it might be possible to record the inputs and outputs from a working model.
    Last edited: Aug 4, 2015
  6. 2005c50

    2005c50 XS400 Member

    I would consider a unit from Pete, but the ones that he makes for the 400 are for the early models with points and mechanical advance as you said. I used one of Pete's units on an 81 xs650 to replace a bad TCI, but I had to install a mechanical advance from an earlier model. Right after I did that, Pete started selling units with electronic advances.:banghead:

  7. pamcopete

    pamcopete XS400 Enthusiast

    There are some models of the early XS400 TCI's that can use the mechanical advancer from the points model allowing you to install the PAMCO. A couple of people here have done that already by sourcing a mechanical advancer on EBay. Take a look at the installation instructions on www.xs400ignition.com to see the similarities between the two.
  8. 2005c50

    2005c50 XS400 Member

    Pete, Thank you for the reply. I looked at your instructions for the 400 ignition, but wasn't aware that the advancer from the older models would fit. I searched the forum for info on installing your ignition, but I guess I missed it. I may be contacting you in the near future if I can find the parts needed to make it work.

  9. xschris

    xschris a lifestyle not a trend Top Contributor

    The 76-77 xs360 and the 77-79 xs400 has a mechanical advance unit in them.
  10. BBS360

    BBS360 XS400 Guru Top Contributor

    Edit: Thought about it again while at work, answered my own question. Wouldn't really work at all.

    Hey Pete,
    I was wondering, it'd be cost prohibitive but out of curiosity, would it work to use two of your e-advancer units on an xs400?
    Last edited: Aug 6, 2015
  11. pamcopete

    pamcopete XS400 Enthusiast

    OK. I found the post by member KC Steve who successfully installed a PAMCO on his sons 1980 XS400 using a mechanical advancer.

    My son recently purchased a 1980 xs 400 which was converted into a cafe racer. The bike was firing wildly and would backfire, misfire or not fire at all. The bike had the original TCI -transistor controlled ignition. Through a variety of trials and with a timing light. I determined the the TCI unit was bad. These TCI units are no longer produced and I didn't want to spend $100 on a used 30 year old electronic unit. Doing some investigation I determined that the 1980 and 1981 xs 400 is the Same basic engine with only the mechanical advance unit and points being the being the differences between the Pre1980 and post 1980 bikes. The engine cases and cams are identical up to production of the DOHC engine in 1982. I discovered that by adding a mechanical advance unit from a early bike (eBay) the Pamco unit can be easily added and wired into the existing system. The entire TCI, coil pickup and rotor is replaced. I was able to wire the new Pamco unit into the existing wiring harness used for the TCI. The bike now has a super strong spark and fires up instantly. I adjusted the timing and the total advance is right on the money. The bike pulls strong and has absolutely no misfiring issues. So, if you have problems with a TCI equipped bike, get an early mechanical advance unit with the Pamco unit and this will fix all of the TCi related ignition issues. The wiring is quite easy and straight forward. I kept the original coils. I also discovered that one of the spark plug caps was bad, so we replaced both. We have now put several hundred miles on the bike in the last 2 weekends with no issues. I wanted to post this as I did quite a bit of research on this looking for an alternative for the TCI with very little luck.
    Herd likes this.
  12. pamcopete

    pamcopete XS400 Enthusiast

    An E-Advancer for the XS400 is doable. In fact I have all the parts consisting of the rotor from a CB360, the E-Advancer for the Honda CB twins and the XS400 plate which is already drilled and tapped to accommodate the sensor boards used with the E-Advancer in the Honda CB's.

    What I need is the ignition timing, advance at idle and full advance degrees at what RPM to build the lookup table for the E-Advancer. I might get lucky and it will be the same as one of the Honda CB's.

    Then I will need a Beta tester with a good running XS400 electric start with no issues. In other words, someone who doesn't need the E-Advancer! This person should have a garage rather than being outdoors and have a good working knowledge of things electrical, as well as being very patient because there will be a lot of trial and error involved. That person should also be relatively close because there may be several exchanges of test parts and lots of Email, so being in the same time zone would be helpful.

    This person will be rewarded with the very first PAMCO E-Advancer for the XS400, namely the one he has worked on.

    And finally, I have to have some indication that the projected selling price of $189.95 is acceptable to more than a few XS400 owners. That is the same price as the PAMCO E-Advancer for the Honda twins, CB350, 360 and CB450. This product would work with both the factory mechanical advancer points models as well as the pre DOHC TCI models without the need to buy a used mechanical advancer. The E-Advancer completely eliminates the mechanical advancer, so even if you have one, its getting old and is a maintenance headache.

    If you want a preview of this product, go to www.cb360ignition.com as that is identical to the proposed product.

    Let me know.
  13. bcware

    bcware Well-read Top Contributor

    I wouldn't be surprised if it was the same. My 1978 xs400 and my friends 1974 cb360 shared many identical ignition components.
  14. 2005c50

    2005c50 XS400 Member

    Thank you very much for taking the time to find the old post about using an early advancer with your system. Advancers are readily available and relatively inexpensive, but I believe a price of $189.00 is a very reasonable price for a complete electronic setup. A used TCI is anywhere between $50 and $150 for a questionable 35 year old electronic component and that doesn't include the pickup.

  15. BBS360

    BBS360 XS400 Guru Top Contributor

    If I had a 400 that needed a TCI replacement I'd much rather spend the money for your system than a questionable used TCI.
    My 360's points seem to work quite all right for now.

    I scanned the info page for the 1977-1984 XS400s from my Haynes manual. This might help with the lookup table.

    Attached Files:

  16. pamcopete

    pamcopete XS400 Enthusiast


    Just what I needed. The CB360 is 10 @ 1200 to 35 @ 3200 so I can use a stock CB360 MCU to get the process started and refine it as we go along.
  17. 2005c50

    2005c50 XS400 Member

    Just to wrap up this thread, I found another TCI and installed it yesterday. The bike seems to be running fine.... no more miss when accelerating. I took it for a 15 mile ride so far and all is good. I did open up the old TCI and inspected the components and solder joints, everything looked fine. In fact, it was very clean for a 35 year old component. Thanks for following along.

  18. 2005c50

    2005c50 XS400 Member

    I've been working (well, not really) with Pete (Pamco) on his new e-advancer ignition for the XS400. I installed his beta advancer and have put about 100 miles on it so far. The bike's running great and starts on the first kick. He wants to tweak the total advance a bit, but even as it is, it seems to accelerate better than it did with the stock TCI.

  19. BBS360

    BBS360 XS400 Guru Top Contributor

    That's awesome to hear.

    Can the advance settings be modified after installation?
  20. 2005c50

    2005c50 XS400 Member

    Base timing can be changed by rotating the mounting plate just as is done on the OEM, but the advance curve and total advance can only be changed by Pete using his electronics magic.


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