49cc head gasket, torque?

Discussion in 'Motorized Bicycle General Discussion' started by jmperry55, Jun 2, 2011.

  1. jmperry55

    jmperry55 New Member

    Joined:
    Dec 3, 2010
    Messages:
    21
    Likes Received:
    0
    I built a 49cc, w/NTTC carb for my Grandson. For reasons I won't go into, he removed the head and put it back on. I found a problem with the spark plug cap which I can fix. But can anyone tell me what to torque the head bolts to? And will I need to replace the head gasket or can it be reused? Given what he has done, anything else I should be aware of or watch out for?
    Don't know what I would do for answers without the kind and helpful folks on this forum.:-||
     
  2. bigbutterbean

    bigbutterbean New Member

    Joined:
    Jan 31, 2011
    Messages:
    2,417
    Likes Received:
    0
    Your manual should say what to torque the head bolts to. Honestly, I never used a torque wrench to tighten my head bolts, and I never had a problem. What I did was go in an x pattern and tighten each one a little at a time, repeating the same pattern until all four bolts were as tight as they would go. You will find when you torque them that they won't go past the recommended amount of torque anyway. I know that from the one time I did use a torque wrench. Just loosen all of them, and with your fingers, tighten them until they just touch the head. After that, use a socket wrench and repeat the x pattern. The gasket is reusable. If you want, you can replace it with the spare that came in the kit, but the one that's on it should be fine.
     
  3. jmperry55

    jmperry55 New Member

    Joined:
    Dec 3, 2010
    Messages:
    21
    Likes Received:
    0
    OK, Bean THX!
     
  4. Al.Fisherman

    Al.Fisherman New Member

    Joined:
    Sep 9, 2009
    Messages:
    1,966
    Likes Received:
    1
    The manual misses that part, at least in every one I've read.

    To answer your question on torque and not a WAG.. here are the recommend torque. I got these online using steel studs in aluminum. Have never blown a gasket in 5 engines, have never stripped a stud hole or stud.

    8mm torques to 150 to 204 INCH POUNDS
    6mm torques to 50 to 60 INCH POUNDS.
    Some engines use a 6mm head studs, I have one.

    Most likely the head wasn't torqued to those specifications from the factory. If not use the head gasket and torque to above. I have used head gaskets more then once without leaking. Before you install the head, mill it. I have NEVER seen a true head. Using a piece of glass and 280 sand paper, sand gasket surface. Only remove what is necessary. The sanded surfaces will stick out apart from non sanded surfaces.
     
    #4 Al.Fisherman, Jun 2, 2011
    Last edited: Jun 2, 2011
  5. DaveC

    DaveC Member

    Joined:
    Jul 14, 2010
    Messages:
    970
    Likes Received:
    0
    Right now Harbor Freight has their 1/4 torque wrench on sale at $12.98.
     
  6. jmperry55

    jmperry55 New Member

    Joined:
    Dec 3, 2010
    Messages:
    21
    Likes Received:
    0
    And I'll be their first customer tomorrow morning, since I can't find the one I used to drag out to satisfy OSHA when I was setting up a swing stage. Thx for the info.
     
  7. jmperry55

    jmperry55 New Member

    Joined:
    Dec 3, 2010
    Messages:
    21
    Likes Received:
    0
    Yeah, not in either of my PDF files that serve as manuals. Thanks for the info.
     
  8. dmb

    dmb Active Member

    Joined:
    Dec 4, 2010
    Messages:
    1,359
    Likes Received:
    0
    crown nuts could pull the studs. i use flange nuts or you could use nuts and washers. don't use lock washers. and re torque after a few heat cycles. good luck
     

Share This Page