General overhaul of a LI serie engine block.
All Innocenti Lambretta engines are over 30 years old now and despite the good
and reliable design and manufacture it maybe time for a general overhaul.
Although a good maintained engine can last for more than 40.000km with minimal
intervention, maybe some new piston rings and some gaskets.
Here underneath you'll find some photos about a complete engine overhaul.
Especially if you thinking to add some extra power to the engine you better be
sure all parts are in excellent conditions.
This section doesn't pretend to be complete but you will have a good idea of the
work evolved. Beware before you begin this isn't a job for beginners, you will
need several specialized and good quality tools.
It's logical that such a job can't be done while the engine is still in the
scooter so prepare to remove the engine:
- Remove both footboards left and right
- Remove rear shock and black rubber engine end buffer
- Remove the flywheel and cylinder cover
- Remove the silencer
- Disconnect throttle cable and air filter and remove the carb
- Disconnect the flywheel leads from the connector block
- Disconnect clutch, rear brake and gear change (2)
cables
- Remove the engine bolt. Sometimes it can be rusted inside so use some
WD40. The washer-method can help to remove the bolt bit by bit. Add some
washer and span the nut until end of the thread, add some more washers and
again span the nut.
- Once the engine is removed start to give it a thorough cleaning.
Before starting with the real stuff begin to remove all the auxiliary parts
like kick starter, gear, rear brake and cloth engager, finally the head, barrel
and piston.
See also the gearbox section and
torque settings
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The flywheel has been removed with the special flywheel puller and holder tool
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Once the crank is out your ready to remove the 4 punch locked screws that hold the bearingplate .
Use an impact screwdriver but be carefull not to damage the insode borders od the casing itself. |
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Once the bearing plat is removed you also can take a paper seal. Then the casing will require some heat to get the bearing out
Use a blow torch to heat up the casing and a punch that fits good to the inner caging of the bearing to drive it out. |
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One of the last parts to remove is the gearbox end plate.
Again the 2 extractor tools from the magflange can be used here also. Be carefull pull the plate off evenly on both sides. Use a screwdriver blade between the plate and firstgear. |
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Endplate removed
Watch the large gearbox shim that trims out the play in the box. Also the needle roller and washer is visible.
Once the endplate is gone remove all the 4 gear sprockets and the gear cluster. Most engine's will have a spacer washer beneat the gear cluster don't loose it. |
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Sliding dog removal
Be carefull when removing the gear selector and the sliding dog. The sliding dog is held in position with a spring and two metal balls. They will pop out on removal, don't loose them! Here you see them laying in the top section of the photo |
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Flywheel side bearing and seals removal
When the magflange is removed it's time to separate the seals and bearing from it. First remove the big clamp, then peal out the first washer. All engine's beside 200' have a spacer next. The heat up the mag flange until you can't hold it with bare hands. Use gloves to knock the magflange on a wooden block until the bearing drops out. Remove the hat type washer and finally the seal. |
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Magflange seal and washers
From left to right all seal and spacers. The right one goes first in the flange to end with the metal clamp on the left side. |
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Fixing the exhaust studs
This Series 2 engine still has 2 M6 exhaust studs where the later types will have M8. Here the thread was damaged so they are upgraded to M8 studs. Drill the holes with 6.5mm and use a standard M8x1.25 tap. |
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A 175cc stage 4 barrel is planned so a little blueprinting on the casing is being prepared. Like this the transfer port are matching the casing
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The drive bearing is back in and the hallith washer with holding plate is ready to go on. Also the drive oil seal is already mounted in the plate.
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Here the mag flange is getting ready, the bearing is filled with high melting point grease
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2 special tools in action; the conrod holding and the crank puller.
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Another look at the work done to the transfer section on the casing
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These parts make the gearbox
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Pay attention in wich ordfer the gears are put back in. The do have a left and right side, check the Home workshop manual.
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Here it's cleary visible which part of the casing needs rounding of to optimize the transfer flow on the barrel.
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An overview of the 175 stage 4 conversion kit
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Those Indian cilinder are not always 100% casted. Here a little hole (2-3mm) was present
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another look at the casting fault
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An error was made in the shipment of the barrel. Instead of a conversion piston 175, there has been included a standard TV 175 piston.
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Again the barrel finish
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A bit blurry this picture but you can get an idea of the use of the engine mount extractor, to remove....
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...and to put back in the engine mounts. A little heat on the casing makes the job easier.
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a new piston (conversion type) arrived and soon the engine was back together.
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New condensor and points were used. Timing was set to 23° (33.5mm on flywheel circumstances). A donor 6-pole Serveta ignition is used here.
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Only the rear hub has to mounted and it's ready.
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Here's a list of replacement parts you will need for doing the engine overhaul.
Complete gasket set:
Different types available for 125/150/175/200 engines including:
gaskets for: engine casing, cylinder, cylinder head, bearing plate (drive side,
round), inlet and outlet manifold, mag flange, ignition cable outlet.
O-rings:
on rear brake, clutch and gear arm, 3 O-rings: 12(inner diam.)x2.5(ring thickness)
on main shaft 22x1.8
Engine mounts:
Standard and wide types available. When using the wide type you will need 290mm
long engine bolt with two M16 step 1.5 threads.
Piston:
16 x 20 x 20 Small end needle roller. (same as P200E)
gudgeon circlips (2) 16mm internal
Drive side:
6305 Bearing (high performance bearing by SKF part# 6305 C3 or 6305 000 retail:
€ 27.
Make sure though that the drive side
bearing is a "C3" grade - this grade of bearing has a
radial internal clearance greater than a normal bearing to allow for the
additional heat build up.
There is also a "high load" version of the drive side bearing - the standard
bearing has seven balls in it and the "high load" version has eight. RS or 2RS means it has a 1 or 2 rubber seals, remove at
least the drive side one for lubrication with gearbox oil.)
33 x 50 x 6 Oil seal (retail: € 7) make sure it is a double lip model (DIN 3760
AS or R23),
recognisable by a AS or RP suffix (A=single lip). 5when a FPM prefix
is used then it is high resistant to unleaded fuel Viton seal.
4x M6x16 flathead countersunk screws to hold the bearing plate, preferable hex
type.
Maybe when the old crank's sealing surface is damaged by wear, Speedisleeves can
be used to compensate.
Most common are seals made of Nitrile (prefix: NBR) which can resist a continues
use at 105°C. Seals made of Viton (Prefix:FPM, colour: brown) are about 50% more
expensive an can be use up to 200°C.
i.e. Nitrile seal with double lip: NBR33x50x6AS
Ignition side:
NU 2205 Bearing (GP200 only) or NU 205 Bearing (all others).
part# SKF GP200 = nu2205ecp all others nu205ecp (extra capacity polymide)
33 x 52 x 6 (retail: € 9,5) and 25 x 42 x 6 (retail: € 5,8) Oilseal
Circlip of 55mm (52mm internal)
Points and condenser
Rear wheel:
The bearing is special made for Innocenti (for example by SKF part# 440029, but
unknown now or 2062)
32 x 45 x 6 Oilseal (retail: € 2,2)
Gear box (endplate):
6004 Bearing
circlip 42mm internal
small tie rod circlip gear arm 6mm external
Kick start shaft:
22 x 32 x 5,5 Oil seal (5,5 not easy to find) (retail: € 6)
shaft circlip 20mm external, piston circlip 18mm internal
Layshaft (X-mas tree):
20 x 24 x 10 inner race (retail: € 4,5)
Mainshaft:
16 x 22 x 12 inner needle roller (retail: € 6)
Clutch:
24 x 28 x10 clutch needle roller bearings (2x) (retail: € 5,6 /piece) or bronz bush on some models
clutch arm circlips: 10mm (external) for lower and 12mm for upper
More tech spec's about rolling bearings on this
Kinex
link
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