pulled plug out hot motor. he need new head?

Discussion in '2-Stroke Engines' started by spunout, Jul 18, 2008.

  1. spunout

    spunout Member

    a young man i never saw before approached me. told me he pulled his plug out, but messed up threads on head. said motor was hot.
    he's going to bring it by monday, and i'd like to be able to tell him the threads can be re-tapped. yes, or no?

  2. stude13

    stude13 Active Member

    hi; you can get a heli coil kit at car part stores.
  3. I would think the heli coil kit, not to mention the labor, would be more than a new head from what I have seen vendors selling them for...
  4. Mountainman

    Mountainman Active Member

    it would be a hard call without seeing the head -- maybe he only messed up a couple of threads calling for an easy fix -- or the head is shot out and time for a new one ? Happy Riding from - Mountainman
  5. So removing a spark plug from a hot engine is a bad thing to do. I never knew that.
  6. spunout

    spunout Member

    i dont know, i havent seen it. although, i'm assuming it's more serious than a couple, based on what he said.
    i told him to just buy a new one.
  7. JemmaUK

    JemmaUK Guest

    The hotter a metal gets the softer it is and the weaker any threads are, which means when an engine is hot you never ever remove sparkplugs. It also expands when hot which can cause other problems.

    When I had one of the humbers i was in the habit of pulling number 1 spark plug to see the engine condition. I once made the mistake of doing that while the motor (alloy head) was hot. Put it back... no problem. That was until I was taking my then partner and our daughter to a naming ceremony near oxford.

    The engine started to sound strange, and then as I accelerated it started making one **** of a racket. pulled over and opened the bonnet and there was a pretty blue flashing thing where something of that nature shouldnt be (it was dark at the time). The engine had thrown out the spark plug!. I shut the engine off and replaced it gingerly - and we got to where we were going..

    Next morning I rechecked the motor and that the plug was tight - and saw a nice image of the spark plug threads on the fuel line coming from the fuel tank!!! the plug had come to rest on the fuel line and had been busy melting its way through it....

    Jemma xx
  8. Mountainman

    Mountainman Active Member

    Well -- pulling a plug while hot is done often -- not perferred -- but is done -- remembering -- to go easy when re-installing -- can strip easy when hot !! I could be wrong -- but -- I am thinking that the amount of torque needed while hot is less than while cold ?? Plus -- protect those fingers -- how many times have I pulled a plug and thought to myself -- dang should have worn gloves !! Happy Riding from - Mountainman
    Last edited: Jul 21, 2008
  9. Skyliner70cc

    Skyliner70cc Active Member

    The reason why pulling a plug is bad has to do with differences in rates of thermal expansion between dissimilar metals. Head is aluminum and plug is steel alloy. When both are hot, removing plug may strip threads or warp the threaded hole.