Primary drive gear on China 2 stroke

Discussion in 'Transmission / Drivetrain' started by dougsr.874, Apr 13, 2011.

  1. dougsr.874

    dougsr.874 Active Member

    On my initial ride on a new 66cc engine the small primary drive gear cracked just above the key way....I have an old discarded 49cc, so I tried to use that is the same diameter , the problem seems to be that the key and keyway in the old 49cc gear is smalled than in the new this possibly true or am I just seeing things wrong....

  2. wbuttry

    wbuttry Member

    anything is possible remeber a 49cc everything is smaller cause a lot smaller engine the crank piston wrist pins keys and key hole you might be able to cutt it longer but i doubt it very seriously it will weaken it dramaticly just order one boy go fast gots them for 5 or6 dollars and decent shipping
  3. retromike3

    retromike3 Member

    same problem different engine

    I had a 66cc motor and the drive cog broke. I ordered another one but it was not the same diameter.
    I had one left from another dead engine but the key way was bigger than the shaft, so I got out my dremil tool and filed half of the key till it fit. I held it in place with a Vice-Grip. I took equal amounts off each side until it slid in.Its worked so far.