How do you de restrict a Scooter using a Piaggio 50cc 2T engine?

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Derestricting a scooter using a Piaggio 50cc 2T engine

De restrict a Scooter using a Piaggio 50cc 2T engine step 1

There are three restrictions in place on the later CAT engines from Piaggio. One is located on the exhaust system, the other in the carburettor and finally the transmission restriction in the variator.

Let’s start with the exhaust system. You have the choice to either de restrict the original system, or simply swap it for an aftermarket exhaust that doesn’t have a run off catch pipe. If you choose to de restrict the original then you will need to start by removing the exhaust from the bike, you will see a fairly large run off pipe that leads to a dead end similar to the one shown in the picture above.

You will need to cut this pipe off near the base and crimp it together, once done weld the crimped edge making sure it’s sealed; you have now de restricted the original exhaust system.

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De restrict a Scooter using a Piaggio 50cc 2T engine step 2

The restriction located in the variator is very easy to remove however you will need a lock tool or impact gun in order to remove the nut that holds it all in place. Start by removing the crankcase cover, this is on the left hand side of your engine where the kickstart is usually found. You can do this by removing all of the bolts around the perimeter then ease it off.

De restrict a Scooter using a Piaggio 50cc 2T engine step 3

Now you can see the drive belt and the front fan pulley which is held in place by one nut on the end of crankshaft. Using your lock tool or impact gun remove this nut and slide the fan lock washer, plastic fan and half pulley wheel off the end of the crank.

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If you pull the belt to one side you will now see that the restriction is visible, you are looking for a spacer-washer that sits on top of a large silver bush “bush pin” which the variator slides backwards and forwards on. The restriction spacer stops the variator moving the full length of the bush pin which in turn prevents the belt from being pushed to the outer point of the variators circumference, because of this speeds above 30mph cannot be reached.

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All you need to do is remove this washer then re install the fan pulley etc as you removed it. Make sure the washer you remove is the one that is over the top of the large cannon bush, any other washers other than this one need to remain in place, just as you found it. Tighten the crank nut back up and re install the crankcase cover.

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You should now see a brass plate with holes pressed out of the face sitting just inside the mouth of the carburettor. Using a flat head screw driver gently prise the plate out of the union. Be careful you don’t bend it when doing this as you may need to reinstall it if the bike is being sold at a later date.

De restrict a Scooter using a Piaggio 50cc 2T engine springs step 7

Now loosen the jubilee clip that holds the carburettor to the inlet manifold and gently pull the carburettor out, if access is not a problem simply rotate the carburettor within its current position so you can open the float bowl.

De restrict a Scooter using a Piaggio 50cc 2T engine step 8

Use a screw driver to undo the two small screws on the bottom of the carb that hold the float bowl in place.

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You should now see a brass jet in the centre of the carburettor, at this point you will see the size printed on the top face of the main jet.

De restrict a Scooter using a Piaggio 50cc 2T engine step 10

Remove this jet and replace with the correct size, if you are sticking with the standard exhaust but the scooter has been de restricted then a 62 should be sufficient. For reverse silencer sports pipes we would normally expect between a 65 and 68 being needed but this could differ from scooter to scooter. Now reverse the process to re install the carburettor and air box.

Job done