Two problems with 5hp Briggs and Stratton

Discussion in '4-Stroke Engines' started by badfish2, Sep 3, 2011.

  1. badfish2

    badfish2 New Member

    So I have two questions about a 5 hp briggs and stratton motor thats recently come into my possession. First, the motor was left sitting in the rain overnight without any spark plug and I'm assuming water made its way into the cavity where it screws in. How much damage can I assume its caused and is there any simple way of getting it out apart from disassembling the entire thing?
    My second issue is this: My pull cord seizes up whenever the spark plug is screwed in. When its removed, it pulls freely as it should. Upon removing the plug and placing my finger near the plug cavity while pulling on the cord I could feel air blowing out AND being vacuumed back in repeatedly. So obviously when I screw the plug in, its blocking this air from escaping and rushing in and that's whats causing the cord to seize. Does anyone know whats causing this pressure build up/vacuum when the cord is pulled and what a potential fix might be? Thanks in advanced for any help.

  2. Old Bob

    Old Bob Member

    You're kidding ...right?
    there may be water in the cylinder,take the plug out and turn it upside down.
    spray some WD-40 in the plug hole and turn upside down, then pull it over a few times quite fast to blow the rest of the water out, put the plug back in and start it
  3. popeye

    popeye Member

    is there a decompression switch for ease of starting? its not unheard of and may be why its difficult to pull when your spark plug is in do you see what i mean? i.e when you remove the spark plug your letting the commpression off so it pulls easy yes? so put the plug back in and find the switch? any one else?
  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    You got it. They use a compression release for easier starting.
    The guy to ask is msrfan who has built a lot of these 5 hp Briggs.

    I have ridden this bike which won the 4 Stroke class at the
    recent Willow Springs race.

    Attached Files:

    Last edited by a moderator: Sep 4, 2011
  5. popeye

    popeye Member

    yay! ive just had my theory backed up, so, i have imparted wisdom and am therefore a man! only took 32 years to get there!
    decompresion switch for the win!
  6. Old Bob

    Old Bob Member

    the compression release is automatic and on the camshaft there is no switch, if enough water got in the engine to rust it enough so it does not function throw the engine out
  7. HeadSmess

    HeadSmess Well-Known Member

    is it the right plug and not hitting the piston?

    water...use methylated spirits or wd40.

    who left it out and why, and how long was it left lying around afterwards?
  8. darwin

    darwin Well-Known Member

    Id squirt some oil in the cylinder and fire that baby up! Belongs on a bike. 5hp that will make a good rat rod the way those briggs vibrate and sound if its like the old upright ones used in minibikes.