How to change the crankshaft on scooter 50 MBK Booster Nitro Peugeot Piaggio

- Categories : Tutorial

In this tutorial we will see how to easily change the crankshaft on a 50cc scooter like MBK Booster, Nitro, Stunt, Peugeot Trekker, Piaggio Typhoon etc. This tutorial is also available in video format.

Required tools:

  • Thick grease
  • Ratchet with sockets

Duration of the operation :1 hour

Dismantling of the clutch bell, clutch, torque drive

First we will dismantle the clutch bell. For this we need the Easyboost clutch holding tool and a ratchet.

Dismantling of the clutch bell, clutch, torque drive

The clutch bell is then dismantled to remove the torque corrector-drive assembly.

Dismantle the clutch-torque drive assembly.

Removing the variator

In order to dismantle the variator, we use the Easyboost variator holding tool. This is delivered with 2 screws to correctly position the tool.

Removing the variator

Using a ratchet with a 17 socket, the variator nut is loosened.

Loosen the variator nut

The ventilated pulley - variator - rollers - variator cap assembly can now be removed.

Remove the fixed flange and the variator

The dismantled components of the variator housing are as follows

View of dismantled components

After removing the electric starter clutch, the 2 BTR screws holding the electric starter gear can be unscrewed.

Dismantle the electric starter gear

The electric starter's freewheel comes by itself. Don't forget the variator spacer that is hidden behind it.

Remove the freewheel from the electric starter

Removing the ignition

The ignition nut on the crankshaft is loosened using the Easyboost ignition holding tool and a ratchet with a 17 mm socket.

Removing the ignition

The Easyboost universal flywheel puller is then placed on the rotor so that it can be extracted.">

Remove the ignition rotor with the Easyboost flywheel puller

By tightening the central screw, it will press on the end of the crankshaft and release the rotor. The rotor, the ignition stator and the seal can then be removed.

Remove the rotor, stator and seal

Using circlip pliers, the circlip, the oil pump driver and the 2nd circlip just behind are removed.

Dismantle the oil pump driver and the circlips

Care is taken not to lose the pawn of the oil pump driver.

Remove the drive pin from the oil pump

Using an Allen key, remove the screw that holds the retaining lug of the oil seal.

Remove the oil seal retainer lug

Dismantle the engine crankcases

Again with the Allen key, the screws holding the ignition side housing and the variator side housing together are unscrewed.

Dismantle the engine crankcases

In order to be able to separate the housings without damaging them, the Easyboost bearing puller is required. The 2 screws are inserted into the threaded holes provided for this purpose, then the clamps are balanced so that it is correctly positioned.

Installing the Easyboost crankcase separator for MBK Booster / Nitro

The housing is then heated for +/- 1min. in order to expand it using a heat gun or gas lamp.

Heat the crankcase on the ignition side with a heat gun

All that remains to be done is to tighten the central screw of the Easyboost housing separator. The housings will then gradually separate.

Tighten the central screw of the Easyboost crankcase separator to separate the crankcases

This is done in exactly the same way for the other side. The housing separator is placed in the spaces provided and the housing is then heated with the gas lamp or a heat gun.

Heat the housing on the drive side with a heat gun

By tightening the central screw of the crankcase separator, the crankshaft gradually separates from its housing.

Remove the crankshaft from the crankcase on the variator side

Dismantle crankshaft bearings

In the majority of cases, the bearings remain in place on the crankshaft during disassembly. In this case, they will have to be removed using the Easyboost bearing remover.

Dismantle crankshaft bearings

If the bearing remains in place in the housing, all that is required is a bush of the correct diameter and a sharp knock to extract it.

Remove the bearing on the ignition side

The procedure is identical for the drive side.

Remove the bearing on the variator side

A trickle of grease is applied to both sides of the bearing remover to facilitate the removal of the crankshaft bearings.

Apply a trickle of grease to the front part of the Easyboost bearing remover

The grease is applied to the rear side of the Easyboost bearing remover.

Apply a trickle of grease to the rear part of the Easyboost bearing remover

The bearing remover is placed around the bearing to be extracted, then the 2 studs are tightened…

Tighten the 2 studs of the bearing bar remover

...until the bearing starts to come off the crankshaft.

Loosen the crankshaft bearings

To complete the work, the central screw of the Easyboost bearing puller must be tightened.

Fully extract the crankshaft bearing

Mount the bearings on the crankshaft

The Easyboost bearing assembly tool is used for the bearing assembly phase. This tool allows the bearings to be mounted smoothly on the crankshaft, easily and safely. The first bearing is placed by putting the bearing writing on the outside.

Mount the bearings on the crankshaft

All that remains to be done is to assemble the Easyboost bearing assembly tool and then tighten the nut in order to "lower" the bearing to the bottom of its housing.

Tighten the nut of the Easyboost bearing mounting tool

The bearing descends gradually and easily on its housing. The same operation must then be repeated for the other side.

Place the bearing on the crankshaft

Cleaning the engine crankcases

It is essential to clean and degrease the remains of the old joint compound with a sponge and a little acetone (or equivalent).

Cleaning the engine crankcases

Mounting the crankshaft in the engine crankcases

In order to easily mount the crankshaft equipped with both bearings, it will be necessary to heat the bearing housing, starting from the variator side, using a heat gun or a gas lamp for 2 to 5 minutes.

Mounting the crankshaft in the engine crankcases

Once the crankcase is heated, the crankshaft is immediately placed in its housing. If the crankcase is properly expanded, the crankshaft will "fall" without forcing into its housing.

Place the crankshaft in the housing on the variator side

Then apply a trickle of silicone sealant and spread it out with your finger or a clean cloth to leave a thin film.

Apply silicone sealant to the housing on the variator side

The housing is heated with the gas lamp or heat gun in order to expand it.

Heat the crankcase on the ignition side with a heat gun

Then, without waiting, the housing on the ignition side is placed over the housing on the variator side. If the crankcase has been properly heated, there is no need to force it.

Assemble the housing on the variator and ignition side together.

All that remains to be done is to screw in the BTR screws in order to hold the 2 housings against each other.

Tighten the fixing screws of the motor housing

Install the oil seals in the engine crankcases.

To mount the oil seals in the engine crankcases, a thick layer of grease should be applied to the internal lips.

Install the oil seals in the engine crankcases.

In order to install the oil seals, it is necessary to use the Easyboost oil seals assembly tool for Booster/Nitro. This tool allows a perfect fitting of the spy joints and thus avoids any risk of bearing breakage. Start with the ignition side, by tapping it a few times with a mallet.

Insert the oil gasket on the ignition side with the Easyboost tool

Then the same operation is repeated for the variator side.

Install the oil seal on the variator side with the Easyboost tool

Reassemble the ignition

All that remains is to carry out the operation in the opposite direction in order to reassemble the various engine components, such as the ignition for example.

Reassemble the ignition

The electric starter

Reinstall the electric starter

As well as the variator

Reassemble the variator with the axle, the rollers, the fixed pully and the cap.

This tutorial is now finished, thank you for following it and see you soon for the next tutorial!

The engine is completely reassembled

VIDEO TUTORIAL

To go further, here is the complete and very detailed video tutorial on the disassembly/assembly of crankshaft bearings:

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