help ! my scooter wont start low compression

Discussion in 'The Workshop' started by yamaha1, Sep 7, 2008.

  1. yamaha1

    yamaha1 New Member

    Messages:
    212
    hi there ive tried pm'ing minor about my knakerd scooter , and i havnt recieved an answer i need help fixing it becuase i NEED to get to work, basically i bent the crank removing my old piston and straightend it ive also noticed there is a small indentation in the crankase face where the base gasket meets about 2 mm deep is this causing the low compression , what could i do to fix it

    are there any other way of upping compression just to get her started, i know the compression low because i put my thumb over the sparkplug hole and turned over the engine but it didnt force my thumb off or put much pressure on it

    please guys i seriously need your help on this one its going to be damn expensive getting a taxi to work and back everyday
     
  2. m1ck_t

    m1ck_t Moderator Staff Member

    Messages:
    3,627
    Rides:
    alot of shit
    the 2mm chip in the cases could possibly be fixed with some chemical metal, and i would say that is a problem, if the gasket is not sitting tightly then its not doing its job really and you loose compression
     
  3. tErr0

    tErr0 Administrator Staff Member

    Messages:
    5,816
  4. m1ck_t

    m1ck_t Moderator Staff Member

    Messages:
    3,627
    Rides:
    alot of shit
    yeah i was going to say something about that too, but thought i'd wait till minor sees this and see wat happens :rofl:
     
  5. yamaha1

    yamaha1 New Member

    Messages:
    212
    oh shit didnt realise sorry minor , i had a metal base gasket but removed it becasue it was split and put looods of that hermatite liquid gasket on


    so what your saying is liquid metal into the dent ..... and then what ?
     
  6. m1ck_t

    m1ck_t Moderator Staff Member

    Messages:
    3,627
    Rides:
    alot of shit
    yeah chemical metal into the dent/dents and file/sand it all down so its nice and smooth, and the instant gasket is most probably your problem mate, its metal for a reason, get a new one asap i'd say, or you could measure the thickness of the metal one and make a gasket old school style out of card paper
     
  7. yamaha1

    yamaha1 New Member

    Messages:
    212
    right will get down to that asap , but do you think the slighly bent crank could be causing a loss in comp ?
     
  8. m1ck_t

    m1ck_t Moderator Staff Member

    Messages:
    3,627
    Rides:
    alot of shit
    probably, but i thought you straightened it?
     
  9. yamaha1

    yamaha1 New Member

    Messages:
    212
    i have but its unbelivably hard to get it perfect , you can see the piston being forced upagainst the sid eof the cylinder ??? could this cause any problems i thought the base gasket only had to do with the scavanging device not compression inside the cylinder ??
     
  10. m1ck_t

    m1ck_t Moderator Staff Member

    Messages:
    3,627
    Rides:
    alot of shit
    well i dont know , but surely its metal for a reason and the thikness of it must contribute to compression. wait for someone else to reply about this mate
     
  11. yamaha1

    yamaha1 New Member

    Messages:
    212
    cheers for your efforts mate really apreciated , from what i know is that the thickness of the base gasket lifts or lowers your cyclinder slightly to change the area your piston compresses the gasses into ? thats why i was wondering how it was a problem
     
  12. m1ck_t

    m1ck_t Moderator Staff Member

    Messages:
    3,627
    Rides:
    alot of shit
    if i am correct , that is called squish :nerd:
     
  13. yamaha1

    yamaha1 New Member

    Messages:
    212
    from what i know .. yes it is but i really want to know if its going to affect it , its got loads of liquid gasket in , i thought i might give it a chance of starting .... oh and one other thing ive gone back to my origional 50 kit that was runing fine when i took it of .. but before i had a 70s kit on - thats what siezed i was running a 102 jet along with the 70s but ive lost my original jet and have gone for a 96 that i had laying around could this richness caus ea massive problem
     
  14. Sw1fT

    Sw1fT Active Member

    Messages:
    2,940
    Rides:
    200SX S13
    can put as much chemical metal around the place as you like, if the conrod is bent and the piston is sitting heavy on one side of the cylinder it aint gonna start for love nor money.
     
  15. yamaha1

    yamaha1 New Member

    Messages:
    212
    and thats the kinda answer i was looking for cheers mister swift

    what can i do ?
     
  16. Sw1fT

    Sw1fT Active Member

    Messages:
    2,940
    Rides:
    200SX S13
    rebuild the bottom end with fresh crank, mains and seals.

    until then i wouldnt even bother trying as it is NOT going to start
     
  17. yamaha1

    yamaha1 New Member

    Messages:
    212
    thanks swift once again but my dilema is ... i dont want to throw all this money at then engine when it might not run because of the indentation in the case
     
  18. Sw1fT

    Sw1fT Active Member

    Messages:
    2,940
    Rides:
    200SX S13
    take a picture of this "indentation", at the end of the day unless it penetrates all the way through to the cylinder/cases, it wont do anything, and even if it does go all the way through, you can just buy 2 gaskets, fit one and chemical metal in the dent, then pull the gasket out, sand down, and fit the other one.
     
  19. yamaha1

    yamaha1 New Member

    Messages:
    212
    ok i took some pics i will put them up in about 3 minuits
     
  20. Crana

    Crana Active Member

    Messages:
    1,056
    new crank?
     

Share This Page