I've re designed the Malossi I have been running for years. First off I am using a Yamaha 47.5mm piston that is taller from the pinn, and longer from the skirt. The skirt was cut 3.75mm to clear the transfer tunnels at BDC. The jug was honed on a drill press to accept the piston, It is set at .0015" clearance. Ring gap is 0012" for the top ring, and 0015 for the bottom. I made a fiberglass shim set at 6mm (total with 2 gaskets) for the base. The transfers are dead even with the piston edge, and the edge is dead even with the top of the cylinder. This left a 2mm squish because of the head design soooo I used a belt sander to mill 2.5mm off the head, and finished polishing with 600 grit to a finished total of 2.75 off. This cut took the head down into the combustion chamber so I had to re shape the chamber. I used a dremmel with a milling bit to cut a new combustion chamber/squish band. I now have a 65% squish band set at .5mm, and a compression ratio of 12.63:1. It now uses a stamped aluminum head gasket instead of the "o" ring type Malossi uses.
I started this build with a 44mm stroker but found tooo many timing problems so went back to the OEM 39mm stroke. It is all together, and almost tuned. I have a 24mm oko on it for now, and have the jetting close enough for break in. This will be the engine that stays on the scoot while I rebuild the Ruima. Once the Ruima is done it will stay on the shelf to be sold with the scoot.
I have run the Malossi to 64mph before on secondary gears only. This case has oem gears that may/may not get changed according to what I find in Primaries for the =Ruima.
The Malossi was running with the stroker but as I said it had timing problems. With the OEM crank it is MUCH better, and oddly enough the jetting went from 128/47 to 115/44. It took three days of swaping parts/machining/measuring but it is all worth it to have that jug back, and running.
