66 cc China Girl after porting

Discussion in 'Video Gallery' started by lazylightning@mail.r, Apr 25, 2012.

  1. lazylightning@mail.r

    lazylightning@mail.r Active Member

    It still has all stock items, I just opened the transfers up wider(even the walls to the fins) and widened the ports. At stock all the port heights were for maximum performance, a pleasant surprise. So I did not change any port heights. Only the piston skirt was trimmed on the intake side. Trimmed it a little too far and lost a little low end power. When it's cold out, it has much more low end, so I figure it's too rich, which it definitely is and the needle is at maximum lean position. Going to solder the needle tip, make it wider to pass less fuel at lower rpm's. I still need to go back in and correct the transfers flow angle with jbweld. And maybe increase the crancase compression ratio. Head and block are both shaved down for increased compression, but I am using a head gasket. Runs pretty good for stock carb and muffler. Cant wait to get an expansion chamber on it and cook up a compact little gearbox. Bicycle = Atom/19.5 inches, too small for me. Had to remount the engine to the left(barely clears pedals now) because of chain line problem with big 2.35 tires. As it turns out, the whole hub was 5 mm to the left from proper center of frame line, worsening chain line problem. Fixed that with two 2mm washers and a grinder for the spacer cylinder for the axle on the other side. Next one is a 29er and a racing engine for a dirt bike.

    This video is from the winter before I ported the engine. It has a different sound. You can't see much after Istart riding because there is no camera mount at that point. Strap held in teeth and camera dangles. The snow on the river was too deep and I had to pedal hard to keep it going....slowly.

    This one has riding at higher speeds on the beaten snow trail. The ice spikes let me do top speed on smooth ice with no problems of sliding at all!

    Last edited by a moderator: Dec 15, 2015

  2. Randall

    Randall Active Member

    Kinda sounds like you are 4 stroking in that 3rd video.
  3. lazylightning@mail.r

    lazylightning@mail.r Active Member

    Maybe so. That was a really long time ago. I have a completely different build now. Half Yamaha, half China girl. Souped up to the gills with a reed, torque pipe and many many more racing mods. Just for fun, not for transport though)))
  4. Randall

    Randall Active Member