Pull Start Pull Start Woes

Discussion in 'Transmission / Drivetrain' started by intheclear, Oct 15, 2011.

  1. intheclear

    intheclear New Member

    I'm installing a pull start and eventually a centrifugal clutch on my bike.
    When I install the pull start, I have to take off the nut that sits in front of the magneto. However pulling the nut causes the wheel to turn and probably the piston to go... how do I lock the engine so I can get the nut off without damaging anything?

    Also, the pull start is large. It will hit the pedal if I put it on. Is there anyway to extend the bike pedals? I can't do much about engine placement... its the highest it will go.

    Any help-appreciated.


  2. HeadSmess

    HeadSmess Well-Known Member

    either remove the chain and jam something between the sprocket and the case,

    leave the chain on and get it to jam between the sprocket and case

    both these methods require a good clutch that wont slip.


    jam a sliver of hardwood between the pinion and clutch gear. a screwdriver works but can slip and or shatter a tooth. hardwood squishes and really gets stuck in there :D

    jam something between the magneto and the rotor... might get in the way of the spanner.

    leave plug in, remove lead so it wont fire up, get ya spanner on the nut and give it a hard quick whack... the only way i do it :D

    that should be enough ideas....

    ooooh! 1 more! get an ngk bprEs....the one with the longer threads. go see a mechanic and ask to look in his bin.... its not for running, its to stop the piston reaching TDC! so dont buy a new one.

    a "bres" wont hit the piston. has to be a projected type (bosch wr8 something? or bpres...)

    pedal clearance. depending what frame you have and what cranks/bottom bracket, you could get a longer(wider) BB axle...about 30 or so on fleabay from memory.

    depends just how much clearance you need
  3. ddesens

    ddesens Member

    Take the spark plug out and use a length of rope that will fit inside the spark plug hole. Feed a bunch of it in and when you go to take the nut off it will compress the rope inside the chamber and keep the motor from turning over. When done just pull the rope out the top and reinstall the spark plug.
  4. intheclear

    intheclear New Member

    Wow, great info people thank you. I'll order a wider axle and keep those tips in mind when I pull the bolts.
  5. HeadSmess

    HeadSmess Well-Known Member

    that rope one is a good idea!
  6. FelipeCobu

    FelipeCobu Member

    This is an old trick used by car mechanics when they have to replace valve springs/retainers/ keepers, now a days they use compressed air.

    Felipe Cobu