smallframe engine strip down and rebuild.
1. Removing the engine from the frame
first thing you need to do before you start any work at all is make
sure you have the right tools. You can do almost everything with
a standard set of sockets and spanners, but you need to have the
smallframe Flywheel removal tool
smallframe Clutch removal tool
permanent marker pen
lot of plastic sandwich bags
(gasoline) or white spirit
and paper for making notes, drawings etc.
for the petrol in the tank, and the old gear oil.
also quite nice to have a Vespa clutch spring compressor, but
you can make your own from a long bolt and a couple of sturdy
washers the right size.
first thing you need to do is drain all the oil from the engine
by undoing the oil drain bolt underneath the engine and letting
it pour into a suitable container. I find a plastic sealable noodle
tray from the local Chinese takaway is absolutely perfect for the
job. If you can, make sure you dispose of it sensibly and dont just
pour it down the drain. Right. Now let's get down to business. First
lift the seat, and undo the bolts holding the petrol tank on. The
seat post takes a 15mm spanner and the small bolts are 11mm. Now
remove the storage bucket. Now make sure the petrol tap is closed,
and pull the fuel hose off the carburettor. As long as the petrol
tap is off there's no need to worry about losing more than the little
bit of petrol in the hose. You'll need to slide the little clip
up the hose first. Make sure you don't lose this piece. Now's the
time to get your first sandwich bag. Put the hose clip, the seat
post and all the tank bolts and washers in the bag and write on
it with the permanent marker to remind you what the hell's in there
when you come to rebuild the engine! Do this every time you remove
something and putting this jigsaw back together again will be a
piece of cake.
remove the tank block up the fuel hose - a bung or screw will do
fine, because you need to turn the petrol tap to the On position
to lift the tank out, then carefully lift out the tank, and drain
off the petrol into your container - I used a well washed 2 litre
cola bottle, but that's cos I'm too cheap to buy a petrol can.
you need to remove the carburettor. Disconnect the choke cable from
the lever by lifting off the hook (leave it on the carb) and disconnect
the throttle cable from the carb by undoing the little brass cable
clamp and then sliding the cable through the cable adjuster. This
throttle clamp is tiny and very easy to lose so either screw it
back on the cable or put it in another bag. The carburettor is held
on by a ring with a large bolt on one side. There is a screwdriver
slot at the top and the shaft is hex shaped. Use either a screwdriver
or spanner to loosen the ring (you'll probably need a spanner to
shift it at first, but there's not much room in there so switch
to a screwdriver once it's loose. Now just shimmy it and the carburettor
of the manifold. Carburettors are delicate things so be careful
with it. There's a rubber air bellows just visible at the manifold,
which needs to be pushed out of the hole so it will come off when
you drop the engine. Once you've done all this the space under the
seat should look like this - huge and capacious!
up is the exhaust. With standard box type exhausts they don't really
get in the way in the first place so you can leave the exhaust in
place for now. With an ET3/SS50/SS90 type exhaust, or most aftermarket
tuning exhausts it is advisable to completely remove the silencer
now as the expansion chamber on these is in the way of everything
else. Luckily the designers of these pipes are not unaware of this
and invariably the expansion chamber can be separated from the manifold
pipe. Undo the 17mm bolt that holds the silencer onto the swingarm
(see the exhaust page for pictures). Depending
on the type of exhaust you have the silencer will either slide off
the loosened bolt or you'll need to fully remove the bolt to get
the silencer off. If it's the latter you may find it helpful to
deflate the rear tyre. Either remove and keep the 17mm bolt safe
or tighten it back into the swingarm.
this point you can remove the rear wheel which will make it easier
to get at certain things such as the rear brake cable, and also
allow the engine to drop at the rear. If you want to remove the
wheel just remove it at the 5 rim bolts, keeping the hub in place.
However before you do this you should lever off the hub centre cap
and make sure you can undo the hub nut. You need to pull out the
split pin before you can turn it. If the nut is stuck fast it's
a damn sight easier to apply force while the rear wheel is still
on. Have someone apply the rear brake (or put something heavy on
the pedal). If it is stuck an impact wrench will shift it, or put
a socket shaft and a 22mm socket on a hammer drill and run it in
reverse with hammer action. If neither of these options are available
to you put your 22mm socket on a normal wrench and while applying
turning force wallop the centre with a hammer a few times. Actually
the hitting-with-a-hammer method of loosening seized nuts and bolts
is one you will profitably refer to on many occasions while rebuilding
your engine. Once it is moving then keep it on there but leave it
loose. Obviously if you are removing the rear wheel then you need
to support the scooter somehow. I use my trusty "milk crate
pinched from outside a shop" that was introduced in the exhaust
article. If you have a blanket or something to protect your
paintwork (or, like me, you simply don't care) then almost everything
from now on is actually easier if the scooter is lying on its side.
you can drop the engine you will need to disconnect all control
cables and electrical connections between the frame and the engine
of the scooter. We'll do cables first as it's more straightforward.
Here are the locations of all the cables:
cable clamps for the clutch and the gear change consist of a shell
with an 8mm hex head and a bolt with a 7mm hex head. This is a stupid
design which will cause you much frustration when you come to reconnect
everything. If you can find an alternative that replaces the 7mm
bolts with ones that can he turned with screwdriver or Allen key
then you will have a much easier time of adjusting your gear cables
at the side of the road in the rain. Who sells 7mm spanners anyway?
To remove the gear cables you will need to remove the gear selector
cover. Inside it looks like this, (but in better focus):
your bike has the original cable outers you'll notice that the gear
selector cables have differently coloured outers. If they are the
same colour then you must mark one of them now. Note which cable
goes to which side of the selector before you remove them or your
gears could end up backwards when you reassemble the scooter.
the cables you need to disconnect all electrical connections.
Most are located in the little plastic junction box bolted
to the swingarm. Remove the cover and you'll see something
like this - note which wire goes where. believe it or not
on this scooter the colours are supposed to match each side
but clearly one set of wiring is a lot older than the other!
the loose wires hanging from the engine and screw the ones
from the body back into the junction box, and leave it hanging
off these wires.
happens now depends on what type of scooter you have. On all
models with points ignition you can now remove the engine
as all the wires are all on the same side of the scooter.
however you have an ET3 (or possibly some model with electronic
ignition, like a 100 Sport or a PK but I've never seen one) the
CDI box is located on the other side of the bike in the cowl glovebox.
You need to disconnect all the LT (Low Tension) wires from this
box (noting where they belong) by pulling them away. They have spade
connectors (on my bike at least) The HT (High Tension) spark plug
lead will not simply pull away. I have heard it can be unscrewed,
but I didn't know this at the time so I cut the plastic protective
tubing that binds the HT and LT wires and removed the HT lead from
the spark plug, leaving it connected here.
all the electrical connections are free you can remove the engine.
At the front the engine is held by one long bolt that goes through
the frame and swingarm. If you laid your bike down you might find
it easier if the bike is temporaily put upright, perhaps using milk
crate technology. Undo the nut and gently tap the bolt through with
a hammer. When you are ready to take the weight of the engine pull
it out the other side to free the engine at the front. At the rear
you can either undo the shock absorber bolt at the top of the shock,
under the seat, or remove the bolt at the bottom of the shock. One
spanner versus two - it's your choice. If you're going to replace
the shock or clean it up then you might as well undo it at the top.
you go, one engine separated from the scooter.