When you clean a carburetor you often need high pressure air. A cheap
solution is to connect a hose with an air pistol to the an ordinary car
wheel. The wheel has to be pumped in between but it is cheap and does
not require supply voltage.
Before removing anything from the carburetor, make sure that the crank
is in a position so the intake is covered. By this you avoid to get
dirt and perhaps parts in the crankcase. If you have to move the crank axis- first put a cloth in the intake hole as a plug.
Be sure that the headlight has good connection since if it disconnects
while the engine is running, there is a big risk that you blow the
rear lamp and speedo lamps due to over voltage.
Do not fit spark plug caps with an internal resistor to old vespas. It
might be less radio interfering but makes starting harder.
Wiring schemes are rarely 100% correct - always write down
connections and colors even when you are taking away the connectors
for a short while.
A useful object when measuring the current through a lamp is a
small piece of paper/plastic with aluminum foil glued on each
side. This can easily be connected between the lamp and the connector
The ampere-meter is then connected with one electrode to each aluminum
piece. Observe that the lamp will not shine until the ampere-meter is
If the headlight flickers when you turn, check that the isolation
is OK in the area between chassis and steering head. This place is
prone to wear due to the movement of the cables.
Sometimes when one tries to remove the flywheel the clip follows
the center nut out leaving the flywheel on its axis. In that case you
can use a clip plier of the opposite type (tips open when you press
the handles) and hold the clip in the groove while turning the
nut. Sometimes it helps to turn the nut so it starts pushing at the
clip, give the flywheel some gentle hits with a small hammer
on the rivets near the flywheel center, release the nut another 1/2
turn, new hits and so on. This helps to release the flywheel from the
axis if it is badly stuck.
When re-fitting the flywheel, be sure to first clean the crank axis
and the hole in the flywheel with alcohol or other fat
solver. Otherwise, even if you tighten the flywheel nut hard, the
flywheel may slip and shear the woodruff key and even ruin the groove
in the crank axis. The drawback is that the flywheel might be harder
to remove the next time.
Always remove the speedometer drive pinion before you remove the
front axis (f.x. when you replace front bearings)
The nut holding the clutch to the crank is a peg nut and can be a
real pain to remove. There is a special tool with the corresponding
pegs in one end and a 17mm hexagonal shaft in the other end that I
STRONGLY recommend. It can be found at most scooter shops and is
only about $15. To remove the nut, bend away the locking washer and
make sure that it is not jamming the sides of the nut. Put a 17mm
socket on an impact screwdriver (they have the same square connection)
and put the socket on the special tool. Place it on the nut and give
the impact driver some short sharp hits with a hammer and voila'- off
it goes. Sometimes some kind of plier or clamp is needed to keep the
clutch from rotating but often the impact is enough to free the nut
before the crank starts to rotate.
The clutch assembly is easiest removed with two screwdrivers
levering it off at opposite sides. FIRST put a rag around the
clutch. There is a woodruff key on the clutch side of the crank axis
and this may fall off. Position the clutch so the woodruff groove
points upwards and lever the assembly off. In case the woodruff key
still falls off it goes into the rag instead of the gear box.
When removal of the cylinder is necessary, and you don't wish to
remove the engine from the chassis: Remove the four nuts and the
washers on the cylinder head. Then remove the cylinder head. Screw two
of those nuts onto one cylinder stud, and tighten the two against one
another. This will make it possible for you remove the stud with a
wrench while you turn the nuts counter clock-wise. Repeat this step
with the other three studs. You should then bring the piston to BDC
(bottom dead center). Carefully, lift the cylinder away from the crank
case (you may need to hold flywheel in place) and slide cylinder off
of the piston, taking care not to hit the paint. You will now be able
to remove the cylinder completely. Remember, before doing any work on
the top end, stuff a clean lint-free rag in the case below the
piston. (this will ensure that no parts or dirt will fall into the bottom
end!). BE CAREFUL: Doing this operation many times may cause wear on
the engine threads - always drop some oil on each stud prior to
re-application and be sure that the stud matches the threads
When removing the spring gear there is a caged needle bearing
inside. Tap on the lay shaft so the needles are visible and place a
rubber band around them. Fully tap out the lay shaft. When re-fitting
the rubber band will slide off by itself when you tap the shaft in
position again. No more crawling on the floor trying to find those
When the vespa makes a clonking noise when shifting, especially
down shifting, this is usually due to a maladjusted clutch. In some
cases though there still is some clutch drag when fully engaged even
when the clutch adjusted so the play is minimum. It is then likely
that the clutch plates are skew. Remove the clutch package as described
previously and compress the clutch using a special tool or a long bolt and
nut. Turn the clutch and check that the plates are perfectly flat. If
not the plates can be hammered flat with firm stokes or even better
replaced. When the clutch is separated also renew the brass ring at the
bottom (from ~1970 and onwards) and check that the springs are
straight and in correct position. Often a bent spring is the cause of
the skew clutch plates. Finally check the pushing plug of the clutch
still has a 0.2 mm deep groove to let oil in.
MAINTENANCE & CHASSIS:
Regularly (at least once a year) take out and grease the following bolts:
Swing arm bolt
The bolt securing the muffler to the engine.
The bolt securing the lower end of the shock absorbers
The one below the crankcase (a long bolt) holding the engine halves
together. The head end of the bolt is at the end of the swing arm.
If these bolts get stuck due to corrosion you will have severe
problems with service/repair.
Wax-type car rubbing is very good to clean aluminum parts with. Take
some on a cloth and rub. It is heavier and cheaper than f.x. Autosol and
gives a very good shine. Especially good on the front hub cap that
often is heavily oxidized.
When replacing the wire sleeve for the clutch, hand-brake, gas or gear wires, first remove the inner wire. Peel off some 10mm of plastic sleeve at one end of the old and the new wire. "Unwind" the metal wire sleeve using a small plier and make a small hook in each wire sleeve end. Connect the hooks and press them together using a plier so they sit really tight. You can now insert the new sleeve while using the old sleeve as a guide to pull it through the chassis. Be sure not to pull to much in the old sleeve so the pressed hooks open.
An empty egg box (multi egg type) is very useful when taking apart
something in a certain order- just put one piece in each egg cup in
the order you remove them and it's much easier to reassemble.
Loosening stuck bolts:
Clean away as much of the corrosion around the bolt as possible
Spray generously with CRC-556, Holts penetrating oil or other
thin oil/rust solver
Repeat step 2 times a day for a week (omit this if you are
in a hurry but it really helps!!)
Heat the area around the bolt with a blow torch or a welder until the oil starts to smoke.(Warm-air guns are too slow, the heat must be concentrated and intense)
Turn the bolts by striking the spanner/wrench with a small hammer. NOTE:If you have to strike on the thread side of the bolt to get it
out - first put on two nuts that are tightened together. The top threads
of the bolt is below the upper part of the upper nut. In this way you
save the top threads and if they still are damaged they will be
restored when you remove the nuts. User short sharp blows and a small hammer.
If this does not help, spray on more solver and repeat 4 & 5
Removing a screw with a damaged head:
My own private opinion is that easy-outs (conical shaped reverse thread screws) should be avoided like the plague. The shape makes the screw expand and stick even harder. Besides the easy-outs are prone to break and are very tricky to drill out. I recommend this method:
Punch a mark for the drill in the damaged screws head. Be careful to have it absolutely centered.
Drill a hole in the center of the screw using a drill that is almost the screw kernel diameter. To do this you need an upright drill. Do not even try to use a hand-held drill. The drill will most likely wander out to the sides and damage the threads.
try to scrape away the top thread screw rests using a large needle or pointed plier, thereby exposing the top threads of the hole.
Use a thread tap of the same size as the drilled screw and cut new threads. If you are lucky (and strangely enough you often are!!) the tap will run in the old threads and cut away the rests of the drilled screw. If it does not - try scraping away more thread to give the tap a new and better grip.