shaking under hard acceleration

Discussion in 'Electrical' started by hippy8717, Jan 3, 2014.

  1. hippy8717

    hippy8717 New Member

    3
    0
    0
    i built a custom chopper using an 01 sportster 1200 as a doner bike. after completing it i have a problem under hard acceleration in 1-3rd gear. the bike starts jumping / bouncing / shaking violently but quits if i let off the throttle. i am running a completely stock motor with stock ignition, stock carb. i have eliminated the VOES by running a ground wire to the ignition and have also eliminated the rollover switch with a ground to the ignition. any ideas on what may be causing this problem? i followed the stock wiring diagram very closely during the build and have double and triple checked all grounds and connections. all connections have been soldered and shrinkwrapped. i have also been having a problem with the battery going dead after about 2 weeks. i suspect the regulator may be bad, i replaced the stator and that got it charging again any help or ideas would be much appreciated.

    i should have added that i have checked and double checked the belt tension, primary chain adjustment, wheel bearings are new, tires are new, belt is new, running a 250 rear, and a springer front. basically the whole bike, frame, etc. is new with the exception of the engine/tranny .
     
    Last edited by a moderator: Jan 3, 2014
  2. dbmg

    dbmg Experienced Member

    5,800
    153
    318
    It seems then that with the high demand needed to increase ignition function that either there is a voltage drop from a sub standard battery or charging system or the motor is moving in the frame and grounding something out or maybe the wiring harness is to short and pulling apart causing fault. Or is it as simple as you are hitting the rev limiter????????
     
  3. tourbox

    tourbox Senior Member

    1,306
    68
    54
    Like dbmg said ,you might be hitting the Rev. Limiter. I would start by placing the VOES back in line. By running it grounded you are fully advanced on timing.At idle, WOT, or anything in between.I'm not familiar with the Rollover switch you are talking about. On dressers with cruise control they have a roll off switch on the return cable. Could you explain the rollover switch to me.
    tourbox
     
  4. BUBBIE

    BUBBIE Well-Known Member

    4,959
    83
    113
    The way I READ It:

    That 01 is a solid mount motor to the bike frame... Correct?

    IF it is FELT shaking the whole bike , it can't be the electrical system. I had a 95 sport, solid mounted and it too shook a Bit but not like you describe.

    I have a rubber mounted sport (06 1200R) and I can Feel the motor (uncomfortable) making some Feeeeeel when totally on the accelerator up to 60, then nothing but GO from there.... Been like that since new...


    OLD experienced members might know More about this is fin_676 a mod and or Hobbit over in the UK... Lots of Sport Bike sense...:s

    You built it and now you'll have to find the fix:small3d023:

    signed....BUBBIE
     
  5. Breeze3at

    Breeze3at Well-Known Member

    4,641
    83
    122
    Could you explain the rollover switch to me.

    I thought he was talking Bank angle sensor?

    My Shovelhead had a bad vibration under acceleration. Turns out one of the motor mount frame lugs was cracked. A break/crack any where in the frame will cause vibration. Very hard to see.
     
  6. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

    5,275
    133
    156
    Solid mount sportsters can vibrate a wee bit it mirrors shake so that I cant see what is behind me if the state of tune of the bike was off the vibration would be enhanced
    With no voes I would think that ignition timing would be wrong on low and medium throttle openings
    The vacuum operated electronic switch adjusts the ignition timing depending on the amount of vacuum present in the carb created by the throttle position
    To remove the voes you would need a more sophisticated ignition module
    Once the ignition timing is correct it would then be possible to correctly confirm the tune of the carb

    Brian
     
  7. Jack Klarich

    Jack Klarich Expert Member

    18,544
    153
    398
  8. hippy8717

    hippy8717 New Member

    3
    0
    0
    Thanks for all the input guys - sounds like i better put in a diff. ign module, maybe a crane HI 4. I did not realize what the VOES does. and it is long gone now. The roll over switch i refered to is the Bank Angle Sensor. and it is also long gone. I have not had it running long so i now have a project to do before spring. I suspected the Ignition may be the problem but now i beleive you guys have confirmed just that. thanks again
     
  9. tourbox

    tourbox Senior Member

    1,306
    68
    54
    Thanks for the clarification on the Roll Over switch. Breeze3at had it figured out. The BAS only kills the ignition if you fall over or lean over more than X# of degrees. It wouldn't of had anything to do with your Shaking.
    tourbox
     
  10. Jack Klarich

    Jack Klarich Expert Member

    18,544
    153
    398
    Harley Davidson Forums here is some info on the Crane system