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Electronic Ignition - Less Vibration

Discussion in 'The Garage' started by Paul Sutton, Dec 19, 2016.

  1. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    I have been looking at electronic ignitions and often see the claim made that following installation the engine runs smoother with less vibration. How true is this, or is just a sales pitch?
     
  2. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    I think it's likely to be true. Ever watched your points ignition with a timing light? Those things wander around like Moses in the desert, It's seldom easy getting both cylinders to fire at the same point. How often have owners changed the points in these old bikes? (Never is my normal guess) I've converted several points engines, the timing goes rock steady especially with e-advance. Starting, idle, acceleration all improve, carbs stop blowing off. Your results may vary.
     
    madmax-im and MaxPete like this.
  3. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Thanks for that gggGary. I have used the strobe light in the past and I know what you mean about Moses. My strobe has been gone for years so just ordered a new one today so will be checking the SH to see if there is an issue with the stock TCI. The bike just seems to vibrate more than the XS1b I had years ago. I do not recall the XS1b vibrating as much as the SH does, and that is after moving to the XS1b from a very smooth RD250.

    Thank you.
     
  4. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    TCI is more accurate than a cam fired aftermarket. My comments were for converting points engines only.
    There have been reports of weak rotor magnets and other "old" components (coil, plug wires, plug caps) causing issues on TCI motors.
     
  5. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    What carbs are you running? The stock jetted BS34's are mighty (too) lean just off idle, these are "early EPA carbs" I found a shim washer under the needle jet got rid of a flat spot and smoothed out power delivery. Good Ole XSJohn RIP was a staunch advocate of retarding timing a bit, (and lowering compression) for a more enjoyable ride. I haven't done either of these. But I have an incurable right wrist twitch.
     
    MaxPete likes this.
  6. 5twins

    5twins XS650 Guru Top Contributor

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    I don't know about smoothing the vibrations but retarding the timing a hair does give better performance in my opinion. Technically, you're really not running it retarded, just at or near the original timing spec these bikes used when first introduced.
     
    MaxPete likes this.
  7. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    You can slot and remove the (riv/screws) that hold the ignition pickup to the stator on the 80-81 if you want to adjust timing. Replace them with regular screws. The factory changed to screws on the 82-84 so ignition timing could be set. That might be a clue about timing being "set in stone".
     
    MaxPete likes this.
  8. pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    Timing lights are critical to the operation of any ignition system, but I have had trouble finding a good timing light lately and still use my 25 year old light that works great. You will probably have to buy one of the more expensive lights to get good results, but don't bother with the preset advance models as that is of limited use for the XS650 or most other motorcycle engines as the preset may not work properly.

    It could be because very few people continue to use a timing light with their cars and we are always looking for the least expensive of anything, especially a timing light if used with an electronic ignition as you probably do not have to set or adjust the timing very often, if at all after initial installation.

    The cheaper and less reliable lights will flicker and miss, especially at higher RPM's, but be patient. As long as you do not detect an actual miss, then the flickering is just the timing light.

    The TCI and most other aftermarket electronic ignitions produce a positive voltage on one of the spark plug wires and a negative on the other. The timing light is designed to work best on the negative voltage wire, but it is not easy to determine which one is the negative wire, so if you are getting erratic operation or even failure to work at all, try switching to the other spark plug wire.
     
    gggGary likes this.
  9. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Thank you gggGary, 5twins and pamcopete. I have taken note of all you have said and will run some simple test observations with the strobe. Interesting that part about the +ve and -ve. Always thought that was the case based on the coil being center-taped according to the schematics. I assume by retarding we go from something like 40 BTDC to perhaps 35ish? But adjustments are out of the question at this stage until I have checked that the advance is working well and coils check out. I have not heard any sign of missing when riding and the idle is very smooth with plug colour looking good following the carb rebuild.

    Thank you for your time and thoughts.

    Note: I have not checked but I think it is 40 BDTC
     
    Last edited: Dec 19, 2016
  10. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    And you only need to look at one side on the electronic ignitions (rephased cranks and the old Martek as exceptions) AFAIK all the current ones use dual tower wasted spark coils. A twisted crank can happen............... That makes em shake.
     
  11. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, 40° BTDC is the later model full advance timing spec. The early ones were 38° BTDC. So, I wouldn't go 5° less, only about 2°. I set my idle timing at or near the right side of the given "range". That puts full advance just a little before the mark. On your late model, you have a "U" mark for the idle timing "range". I would set it on the right leg of the "U" .....

    [​IMG]

    You have no full advance mark on your TCI machine but you can use the left side of the drain slot on the bottom of the cover opening .....

    [​IMG]

    Retard it a little and you will be nearer to the right side of that slot.
     
    littlebill31 and Paul Sutton like this.
  12. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Excellent 5twins, very handy little trick.
     
  13. 5twins

    5twins XS650 Guru Top Contributor

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    It's actually a Pamcopete trick, lol. Well, the advance timing mark that is, not the slight retard trick.
     
  14. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Back in the day of point ignitions for bikes I was buying Echlin Gold point sets from NAPA, I had to beg the NAPA dealer to order these for me because he was a good friend of the Honda dealer next door. Those Echlin points had a much stiffer spring than the OEM points resulting in an easier tune and a smoother running bike. I'm a true believer that the spring in those point sets is a very important factor. Echlin may still manufacture points for bikes but I have searched more than once and have not found them.

    Scott
     
  15. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, the spring is a wear item on a points set which many people don't realize. That's why you should replace them every 10 to 15K miles even if the faces still look OK. The last ones I replaced for a guy were due to this. They quit working because the springs got weak. They wouldn't close consistently and/or tight enough to make good contact and that meant the coil wouldn't charge up for the next spark. The bike would barely start and if it did, up and quit after a few seconds. New points made it a one kick starter.
     
  16. aldo5468

    aldo5468 Redleg XS650.com Supporter

    I'll see your 25-year old light and raise you my 50-year old Knightkit! Looks a little ratty now but still works like a champ!
     
    MaxPete and roadrash61 like this.
  17. grizld1

    grizld1 Grumpy old man Top Contributor

    For some reason factory specs back in the day called for ignition to be set to the maximum feasible advance. Forget about fuel changes and all the other stuff we like to grouse about: even back in the day Gordon Jennings was commenting on that quirk. Why did the factories do it? I dunno, maybe they sold more pistons that way. Anyway, if you go to www.strappe.com, click the button for tech articles, then click the spark plug icon, you'll find Jennings' recipe for checking the ignition advance by reading the clean burn line on the electrode tip of the spark plug--and a lot more. It's one of the best motorcycle tech articles ever written.
     
  18. peanut

    peanut XS650 enthusiast & inveterate tinkerer Top Contributor XS650.com Supporter


    definitely ! I was amazed at how little vibration I feel on my 79 Special, practically none although I should add that I'm using the original ape hanger bars
    Its fitted with a Boyer Bransden Micro Digitall fuly electronic advance and ignition system. KIT00303

    When the timing is set correctly and the engine has the correct amount of advance throughout the rev range, the engine runs incredibly smoothly.
    http://www.boyerbransden.com/microdigitalmicropower.html
     
    Last edited: Dec 20, 2016
    Paul Sutton likes this.
  19. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Thank you grizid. Very interesting article! I will have to read it a couple more times and then try to apply it, especially that part about magnifying the electrode for the fine detail.

    Thanks.
     
  20. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Peanut, thanks for that info. I am thinking of going Boyer but first plan to give the stock electronics a good test later this week when my new strobe lamp turns up. I will replace the transistor, diodes and that long black 14 pin chip (Quad Comparator - replace with LM2902N). I hope this will help but must do it all systematically. I will be looking for timing advance stability and decreased vibration. Could be a waste of time also?

    Thank you.
     

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