From Moped Wiki
Instructions for Metrakit.
- Compression: All of our kits are made with the appropriate compression such as complete top ends and without head.
- Crank arm: Once you have taken the cylinder apart, check the connecting rod on the crankshaft. There shouldn't be any vertical play, and the side-to-side movement should exceed 0.7 mm.
- Piston skirt: Check the piston skirt for damage. If there is any, trade it for a new one.
- Ports: If possible and if you have the tools, touch up the ports so that they match the cylinders as close as possible for a better flow of gases. (aka chamfer your ports).
- Cleaning: Clean the piston ring slots very well. Grease up the ring grooves as well as the cylinder and piston.
- Piston: Important -- the piston has an arrow on it pointing to the exhaust port.
- Important: Bolt the cylinder head on in a criss-cross (like an X) pattern.
- Tuning/Timing: Set the ignition timing to 1.8 mm to 2mm before top dead center. Change the spark plug for a grade equivalent to NGK B7HS.
- Carburetor: Increase its size up to a maximum of 21mm, and adjust the jetting appropriately depending on your altitude, climate, and other installed parts.
- Lubrication: Use synthetic two-stroke oil.
- Breaking in: It is recommended that for the first 300 km (200 mi) you do not go WOT. This way your cylinder will last longer. It's also recommended that you increase your oil by 1%, so if you are using 2% go up to 3%.
- Exhausts: If you want more options we have a wide catalog and variety of exhausts . Metrakit is not responsible if you choose to use another brand's exhaust.
This is not included in the instructions:
During break in, it is recommended not to run synthetic oil. Petroleum based oil promotes easier wear for piston rings, which will allow the kit to break in better/sooner.