How to change the crankshaft and bearings on a 50cc Piaggio scooter?

We start by removing the clutch bell using the Easyboost 4-in-1 clutch tool.

We install the Easyboost variator holding tool for Piaggio on the crankcase so we can lock the fixed pulley half and loosen the nut.

We remove the variator, the bushing, the rollers, the spacer behind the variator, as well as the oil pump gear.

We lock the ignition rotor using the Easyboost rotor holding tool. Then, using a ratchet, we loosen the ignition nut.

Using the Easyboost M24/M26 flywheel puller, we can extract the ignition rotor without difficulty.

Using a screwdriver, we unscrew the 3 stator screws as well as the 2 screws of the "pick-up" unit.

Using a ratchet and an 8 mm socket, we can remove the electric starter.

We unscrew the 8 crankcase assembly screws.

Before separating the crankcases, we must not forget to remove the ignition woodruff key using pliers.

To separate the crankcases without damaging them, we install the Easyboost crankcase separator on the ignition side to start with.

Using a heat gun or a blowtorch (gas), we heat the crankcase on the ignition side (for +/- 1 min) in order to expand the crankshaft bearing housing.

Without waiting, we tighten the central screw of the separator, so as to gradually separate the engine crankcases.

We repeat the same operation for the variator side, by installing the Easyboost crankcase separator.

We heat the variator crankcase, just as previously done for the ignition side crankcase.

We tighten the central screw of the separator, so as to remove the crankshaft from the variator side crankcase.

Using a flat screwdriver and a mallet, we extract the oil seal by tapping on the screwdriver.

Using a socket fitted with an extension bar, and a mallet, we extract the oil seal by tapping on the extension bar.

When a crankshaft bearing remains in place in the crankcase, a bearing puller must be used so as not to damage the crankcase.

We heat the crankcase again (+/- 1 min.) in order to expand the bearing housing.

All that remains is to tighten the central screw to allow the extraction of the bearing, without difficulty.

Using a sponge, acetone and brake cleaner, we clean the crankcase thoroughly, so as to leave no residue.

In case the bearing remains in place on the crankshaft, simply use the Easyboost 2-in-1 bearing puller so it can be extracted without difficulty.

At this stage, we can change either the crankshaft, or only the crankshaft bearings. In this tutorial, we are only going to replace the crankshaft bearings. To do this, the Easyboost bearing fitting tool must be used.

We repeat the same operation for the ignition side, using the Easyboost bearing fitting tool. Fitting the bearing on the crankshaft is done (almost) effortlessly!

We heat the crankcase again to allow the bearing to be fitted without forcing.

Once the crankcase is well heated, we can insert the crankshaft into its housing. The bearing should "drop" to the bottom of its housing without having to force, due to the expansion of its housing.

We apply a bead of gasket sealant and spread it so as to leave only a thin film.

This time we heat the ignition side in order to expand the bearing housing.

Without waiting, we fit the ignition side crankcase onto the variator side crankcase. It fits into place without difficulty.

We refit the 8 crankcase screws, making sure to tighten them in a cross pattern.

It may happen that the crankshaft does not turn freely after tightening the crankcase screws. If this is the case, simply tap on each side with a mallet to free it.

To install the oil seal on the ignition side correctly and without difficulty, you need the Easyboost oil seal fitting tool. It allows you to place the oil seal exactly as it was originally, thanks to very precise machining.

We repeat the same operation for the variator side, using the Easyboost oil seal fitting tool.

All that remains is to refit the various engine components. We start by refitting the ignition stator…

…then the woodruff key on the crankshaft.

We then refit the ignition rotor using the Easyboost rotor holding tool, then the electric starter.