So here is the thing, they call the M0 series Polini 65cc's, they are barely 57cc's, keep that in mind, also those damn MK3 pipes!? Why do they stick the header 8 inches into the chamber? The world has no answers for these uestions, anyhow the bike. I picked this thing up for about 75$ and the paint really shows it, so I decided to port a stock cylinder, and had, well less then stellar results, so fuck it put a kit on it! A buddy had a bunch of old Polini's so I picked one up, I used a stock M1 reed block (ported a bit) with some Polini reeds that I cut, cut the pipe in half and tore out the shitty to long header thing, welded it back together, added an M1 MLM VM18 intake (20mm id on those bad dudes), thankfully it had frame clearnce, as I've said on other M0 Polini's, a large carb really wakes these up. Another trick with the M0 motors seems to be leaving the stock clutch springs, they just dont react well to the GY6 springs, now it takes off well and its a respectable 46-48mph which is way to fast with quill stem bars and a Puch Chopper seat. UPDATE: Shocker I rebuilt the motor, though it still ran strong. Fresh bearings/seals/gaskets/tires/tubes/re-timed the cdi. God these little Polini's are such rippers, still does damn near 50, still ugly, here's a little video of the first start post rebuild Side note, I put an nos crank in this, I put the Treats full circle crank in my m1, it was a mistake, I dont know why but these motors really prefer the half moon style stock crank size, stick with it. https://youtu.be/uNFjPawhzY0