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Best ignition timing setup? - points to TCI swap

Discussion in 'The Garage' started by RyanJL, Sep 14, 2020.

  1. RyanJL

    RyanJL XS400 Member

    Hi all,

    Looking for some advice regarding best ignition timing for TCI on my particular bike.

    I'm converting my XS400 from points to TCI at the moment. The engine is running Mikuni VM32 carbs, pod filters, modified exhausts, and was previously dyno tuned with the points ignition. It ran well, and made good power, but one coil has since started to fail so I'm switching over.

    This photo shows how the points were set when dyno tuned - quite a lot of ignition advance from what I can tell.


    Here's a closer look.


    I've since installed the TCI rotor and pickup following the Haynes manual, with ignition timing perfectly aligned to the LF mark on the alternator rotor as it would be when stock. You can see here how that looks.


    Is this the best possible option for timing given what we know above about the best tune for my bike with points ignition? Would you dial in a little bit more advance with the TCI than 'standard' to start with? Or just let the TCI unit do that itself? I'm sure it will run with the timing like this, but if I can make it run better - or not worse than before - that would be great.

    Thanks for any and all advice.
  2. RyanJL

    RyanJL XS400 Member

  3. amc49

    amc49 XS400 Addict

    You absolutely NEVER rely on those timing plate marks as to where your timing is, you rely only on where a timing light indicates on wherever the timing mark is on cam or crank preferably crank (LF mark on rotor).
  4. xschris

    xschris a lifestyle not a trend Top Contributor

    Yes , set it with a light. Your TCI box has a pre-set advance curve it it. The manual I think has the numbers.
    Scotty4 likes this.
  5. amc49

    amc49 XS400 Addict

    There may even be a very slight amount of retard at much higher up, it can be helpful. Most magnetic impulse setups do that automatically to some small degree.
  6. RyanJL

    RyanJL XS400 Member

    Thanks for the replies, chaps. I'll leave it set by the book to the LF mark for now and get it running again. If it doesn't feel quite as strong as before I might try winding in a fraction of base advance and see how the TCI module copes with that.

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