too much compression. ..?

Discussion in 'General Questions' started by tim85, Dec 15, 2014.

  1. tim85

    tim85 New Member

    I've just recently replaced a piston head that had a pretty decent gash in it, and also replaced the cylinder. Since I did this, the motor seems to have way too much compression. The piston and rings are 47mm, and I measured the cylinder to be 47mm also. I made sure no debris fell from the damage parts I replaced, and the engine is not siezed. The piston does move freely when turned manually from inside the clutch case, but this is while the cylinder head is off. With the head on, it will not move at all. Does anyone know if I've done something wrong, or what the problem might be?
     

  2. Chainreaction

    Chainreaction New Member

    If you remove the sparkplug you will have zero compression. If it still doesn't turn over right you might have a clearance problem probably.
     
  3. butre

    butre Well-Known Member

    pull just the spark plug, not the whole head. try turning it over that way.
     
  4. tim85

    tim85 New Member

    I don't see how there could be a clearance problem. Everything was in perfect order before i had to swap the piston/ cylinder
     
  5. butre

    butre Well-Known Member

    there are two different types of 66cc engines that have a few non-interchangeable parts (including the piston and the cylinder), you may have gotten pk80 parts when you needed gt5 parts or vice versa
     
  6. tim85

    tim85 New Member

    I'm going to try a different piston head on it but if this doesn't work I'll just buy a whole new kit, that way I'll have a bunch of spare parts.
     
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