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  1. #21

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    Quote Originally Posted by MFC View Post
    The instructions I’m following says to adjust the timing at 35 degrees before top dead center. The line is top dead center. Should I be adjusting the timing at TDC ?? I was under the impression it’s supposed to fire at 35 / 40 degrees BTDC. Am I wrong ??
    You are doing it correctly. Forget the line. Use the advance timing mark.
    Now, did you have to move the timing plate from its former position to set the timing? That is an important question.

    Jim

  2. #22
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    Yes I did. But how would the position of the back plate affect the timing of when the trigger fires the electronic ignition. The install instructions don’t say to install the VT-i at a certain spot ... so I assume all that matters is that the trigger is set to fire correctly at 35*
    Click image for larger version. 

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  3. #23

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    The position of the timing plate (pickup) is what determines when the ignition fires. It would be good to know if after you timed it, it was in the same position as earlier, indicating that the timing before was correct, or if you had to advance or retard it to achieve correct timing. You are trying to diagnose and tune a machine that is new to you. The more information you have, the easier it will be. You seem bright enough to grasp this, it will be interesting to see how you proceed with the actual tuning, as it were, from scratch.

    Jim

  4. #24
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    I understand now. I did take a photo of where it was prior so if I need to start over I have a starting point.

  5. #25
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    Quote Originally Posted by FatChibs View Post
    it sounds like you need to readjust your clutch to me
    Im going to adjust the clutch today.

  6. #26
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    Quote Originally Posted by MFC View Post
    Im going to adjust the clutch today.
    If that doesn't work take it apart and inspect the clutches if you have never been in there before........

  7. #27
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    Will do Tattoo... I thought I would ask about this also... yesterday when finding my advanced mark and TDC mark I noticed the flywheel had some holes in it.... not sure what this means can anyone shed some light on this ?? here is a pic of the holes I am talking about

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  8. #28

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    The holes were drilled to balance the flywheel assembly. The holes can be on the inside or the outside of the flywheel, sometimes both. (If outside, visible through the timing hole.)

    Jim

  9. #29

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    Once you are satisfied that the timing is correct, and with a NEW set of plugs gapped correctly (.032 - .035), if the motor doesn't pull cleanly through the rpm range, you need to address carb set-up and jetting next. I list carb set-up and jetting separately because they are separate issues.
    Example, with the velocity stack or ring in your pic, you would be well paid to remove the plug in the bottom of the bowl vent passage, and install it in the face hole behind the velocity stack. Leaving that hole open as in your pic has been known to create a vacuum in the bowl at speed. Bernoulli effect and all that.
    Next is float level, which I find wrong on S&S carbs more often than I find it correct.
    Also, good carb and intake mounting, with no vacuum leaks.
    Lastly, jetting, which might make a thread all by itself.

    Jim

  10. #30
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    Quote Originally Posted by JBinNC View Post
    Once you are satisfied that the timing is correct, and with a NEW set of plugs gapped correctly (.032 - .035), if the motor doesn't pull cleanly through the rpm range, you need to address carb set-up and jetting next. I list carb set-up and jetting separately because they are separate issues.
    Example, with the velocity stack or ring in your pic, you would be well paid to remove the plug in the bottom of the bowl vent passage, and install it in the face hole behind the velocity stack. Leaving that hole open as in your pic has been known to create a vacuum in the bowl at speed. Bernoulli effect and all that.
    Next is float level, which I find wrong on S&S carbs more often than I find it correct.
    Also, good carb and intake mounting, with no vacuum leaks.
    Lastly, jetting, which might make a thread all by itself.

    Jim
    Thanks Jim,
    I will get the timming sorted out today and then move on to the other issues if need be.

  11. #31
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    Jim, in regards to the carb... what screw are you talking about ??? I think your saying to take the screw (9) and put it into (8)

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    Last edited by MFC; 07-17-2019 at 10:43 AM.

  12. #32

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    I'm talking about plug #21.
    Put it in position #8 in the upper pic.

    Jim

  13. #33
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    how will I know that I am satisfied with the timing. no pinging noise at 2000 RPM???
    Also, what do you mean if the bike doesn't pull cleanly through all the gears??

    Sorry for all the questions, I am trying to cover my basis with the mechanical part of having an ironhead, I'm better with the fab stuff.

  14. #34

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    What I mean by pulling through the gears is just that. It should pull strongly from 1500rpm up to at least 6000rpm with no hesitation, missing, sputtering, etc. And an ironhead will pull rather strongly. It should not go flat until the valves start floating, and they have enough valve spring to turn 7000rpm. Looks like you have plenty of carb, a nice exhaust system (from appearance only) and you say you have an electronic ignition which should give consistent spark. Tuning should achieve this result.

    Now, if there is something (or several somethings) mechanically wrong with the motor, no amount of tuning will fix that. That remains to be seen.

    Jim

  15. #35
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    Valve timing too ...

    Being that motor is a 81 it's most likely to have a world of miles on it ...
    Bout the first thing that wears out is the lifter blocks ... The rocking back and forth throws off valve timing greatly ....

    Easy to see if indeed this is the case by pulling the pushrods covers and lifting them up to eye-ball what the tappets are doing while spinning the motor over ...
    At high lift you will see it jump from side to side ....

    If you do need a set of blocks, I have these in stock...



    Sell em cheap .... They are brand new ...
    Last edited by Dragstews; 07-17-2019 at 1:05 PM.

  16. #36
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    Quote Originally Posted by Dragstews View Post
    Valve timing too ...

    Being that motor is a 81 it's most likely to have a world of miles on it ...
    Bout the first thing that wears out is the lifter blocks ... The rocking back and forth throws off valve timing greatly ....

    Easy to see if indeed this is the case by pulling the pushrods covers and lifting them up to eye-ball what the tappets are doing while spinning the motor over ...
    At high lift you will see it jump from side

    If you do need a set of blocks, I have these in stock...



    Sell em cheap .... They are brand new ...
    Thanks !! This will be another thing on the list I’ll check

  17. #37
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    So here is the update.

    I set up the timing light and followed the directions on the vti PDF. I was only slightly advanced from 35* BTDC. Retarded about 5 degrees And jumped on the bike.

    Like Jim said I pulled through all the gears and listened for a ping noise.. none, bike fired perfectly, sounded great. However the plateau issue still existed. So I adjusted my clutch cable first. Got back on and still I could feel the bike lag then catch. Adjusted my pressure plate and again the cable and BINGO the bike pulled through each gear beautifully!! Powerful and sounding best it has been in the time I have had it.

    Question Jim, if I swap the plug like u suggested what will that do to the current tune?

  18. #38
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    Quote Originally Posted by MFC View Post
    So here is the update.
    Adjusted my pressure plate and again the cable and BINGO the bike pulled through each gear beautifully!!
    Awesome.....

  19. #39
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    Quote Originally Posted by Tattooo View Post
    Awesome.....
    Thanks Tattoo ... turned out the clutch needed some adjustment to get it right! I appreciate the guidance!

  20. #40

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    Quote Originally Posted by MFC View Post
    So here is the update.

    I set up the timing light and followed the directions on the vti PDF. I was only slightly advanced from 35* BTDC. Retarded about 5 degrees And jumped on the bike.

    Like Jim said I pulled through all the gears and listened for a ping noise.. none, bike fired perfectly, sounded great. However the plateau issue still existed. So I adjusted my clutch cable first. Got back on and still I could feel the bike lag then catch. Adjusted my pressure plate and again the cable and BINGO the bike pulled through each gear beautifully!! Powerful and sounding best it has been in the time I have had it.

    Question Jim, if I swap the plug like u suggested what will that do to the current tune?
    If you swap the location of that plug, hopefully nothing. Drag racers discovered that with a velocity stack, a vacuum can be created at that point at high speed. That is why the plug is there to start with, to give you the optional vent point when not running the air filter box. You need to swap it.

    Jim

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