Original here: French_tuning_for_Peugeot_102
On the cylinder:
1.File the base of the intake window so the total height is 17mm and the bottom is curved like the first figure (the one to the left of the section labeled “La Carburation” on the second page).
2. File the top of exhaust window so that the total height is 11.5mm, like the second figure (the one to the right of the section labeled “Le piston” on the second page.)
On the Piston:
1. Cut of the little connectors on the sides of the base of the piston below where the wrist pin is inserted like the second figure on the third page (the one to the left of the section labeled “Transmission Secondaire”).
2. Cut 5mm off the bottom of the piston skirt on the intake side and be sure the width of the cut matches the width of the intake on the cylinder (see same image as the previous instruction).
On the head:
1. Take 2.85mm off the mating face of the head, so that the compression ratio is 10:1. *This could be achieved in part by ditching the gasket and lapping/truing the cylinder and head mating surfaces (*this is my note, not in the document, also I would focus on the ratio more than the mm off just to be sure you don’t take too much off).
On the Carburetor:
1. If you keep the stock carb and exhaust, keep the air filter and change the jet to a 22.4.
2. However, it’s better to use an intake that is short (60mm) in length and 15mm in diameter and use a Dellorta SHA 15mm with a 66 jet.
On the Ignition:
1. Set timing to 2.2mm before top dead center.
2. Use a spark plug with a thermal rating of 260 like a KVAS 1100.
On the Exhaust:
1. Take the original off, clean it, set it on a shelf cause its better as a decoration.
2. Use the Fresco pipe designed for a 103 (this is a pipe that was popular in this era.) On the Variator:
1. Remove 3 balls, place the remainder in a triangle.
On the Secondary Transmission (gearing):
1. For fast tracks with long straights, use a 12T front sprocket.