0 items
Checkout >

Avanti Fitting Instructions


 Avanti Fitting Instructions 


Only to be fitted by a competent person, if you are in any doubt about the fitting of this kit, ask a skilled technician or telephone us. Better to be safe than sorry. 

Your Lambretta must be in a Road Worthy Condition before fitting the Avanti Kit. 

Engine requirements / recommendations 

Top quality main bearings and crankshaft (107mm conrod), do not use Indian SIL main bearings or crankshaft unless it has been converted. 

Clutch: Crown wheel, spider & pressure plate must all fit well and be in good condition. 

Fit good quality clutch plates either 4 or 5 plate (or better) with strong springs and 

make sure these do not become coil bound. 

Gear ratio / 


Any of the following matching the right exhaust system, please ask for 

advice for your ideal road requirement

4.44:1 Standard TV/GT200 or LI150 with 47/18 sprockets or any combination to achieve 

this ratio use Old style Taffy pipe, Chiselspeed ADS-3, Avanti Clubman 

4.6:1 LI150 with 46/17 sprockets, JL3, Franspeed Road, Avanti Clubman 

4.7:1. GP200 with 47/20 sprockets use JL3 0r Franspeed Road pipe, Avanti Clubman 

or 42mm Clubman Modified 

4.8:1 SX200 with 46/15 LI150 with 48/17 use Franspeed Race or Avanti big bore 

JL3 / Franspeed Road 

Carburetion: Ideally use a 30mm carburettor or larger but you may use what ever your 

preference might be, albeit that performance may suffer if you use a 

smaller choke diameter. 

If you use a 22mm through the air box do not use an air filter. 


For top end performance use a Franspeed Race Expansion Box, modified to Fit, 

General road use: Franspeed road or JL3 modified to fit 

Clubman, our Avanti Clubman has been designed to run with this kit. 

If you use any other clubman type exhaust it will result in lower performance 

and will also be liable to over heat the engine. But you can use a modified one. 

Note: Any clubman type exhaust will fit this kit but expansion boxes may 

need brackets to be altered 

Flywheel: Recommend a Standard SIL flywheel lightened and strengthened 

Minimum requirement: strengthened 

To fit the Avanti Kit 

First Wash the Cylinder, Head & Piston using Clean Petrol & dry, smear some 2 stroke oil to the bore. 

1. Remove the engine bar and drop the engine and support, if you have standard length cylinder studs change these with the ones supplied with the kit. 

2. Fit one of the base gaskets supplied and check to see if the crankcase needs to be 


“matched”, if it does make sure that no surplus metal enters the crankcase 

assuming that you still have the crankshaft fitted. 

3. Not all crankcases are the same, for this reason we have supplied 3 x base gaskets, 


1x 0.4mm, 1x 0.75mm & 1x 1mm. If you have a SIL Crankcase fit the 0.4mm 

gasket. Fit the piston without the rings, fit the Cylinder and push down on the base 

gasket as tight as you can. Move the piston to Top Dead Centre (TDC). 

Measure from the top of the cylinder to the edge of the piston, this measurement 

must be between 3.2mm & 3.5mm, (not more & not less) this can be adjusted by 

using the gaskets supplied. The reason for this is to adjust the squish clearance. 

The head has a recess of 2mm thus leaving a squish clearance of between 

1.2mm – 1.5mm. 

For original Innocenti crankcases start with a 1mm base gasket. 

4. Remove the cylinder, fit the rings & refit the cylinder, make sure that you take 


care locating the rings on the pegs and that the rings do not get caught in the inlet 


5. Fit the cylinder head, smear some gasket silicon to it’s face first, use 4x 8mm flat washers and 4 x 8mm wave washers 


with the long 8mm nuts supplied, tighten to 20ft/lbs. 

6. Fit your inlet manifold, nuts, bolt & washers supplied. 

7. Refit engine bar. 

8. Fit exhaust & head cowl, use the 3 x 8mm “Button Bolts” with some “thread lock 

tight” to fit head cowl. 

9 Set static Ignition timing to 17 degrees BTC 

If the Avanti Kit has been fitted by a dealer this MUST be handed to the Purchaser 

WARNING You must read this before riding your new Avanti Kit 


Alloy Nickel Silicone Carbide cylinders have been used for many years and you may well have owned one. However this kit is different and you MUST follow these instructions to the letter! If you think you can just bed the rings in for 50 miles or so and go for a blast then you had better think again. Please be patient follow the instructions, if you do not, I will know. 

Whilst the TT3 will be more forgiving to heat seizures than other kits, ignition timing and jetting of the carburettor is still critical at any time but more so during the initial set up and running in period. At . throttle you are running on the pilot jet, if this is weak you can still seize an engine even at 35 mph. 


Cold piston seizures 

This is a condition where a piston expands quicker than the cylinder in certain conditions, causing a piston to seize. 

Because this engine runs cooler than any other Lambretta air cooled kit you MUST WARM THE ENGINE BEFORE moving off for about a minute even after running in. Keep engine RPM down to about 3,000 rpm for the first mile. 

In Cold Conditions make sure you allow more time to warm the engine up. 

This Kit also has a central exhaust port and care must be taken whilst running in. 

Always use good quality synthetic oil, whilst running in use at 4% for the first 500 miles, thereafter this may be dropped to 3%. Use an NGK B8ES spark plug or equivalent whilst running in then maybe changed if necessary to a B9ES 

Running in 

First 200 miles stay below 45 mph and vary the speed (RPM) 

Next 200 miles stay below 55 mph and vary the speed (RPM) 

Next 100 miles stay below 65 mph and vary the speed (RPM) 

For the next 250 miles keep varying the speed whilst gradually increasing the speed, do not hold at maximum speed for any length of time. Do not hold at maximum speed until you have done at least 750 miles. 

Extra care must be taken whilst running in if you are running into a head wind or going up hill, slow down and use a lower gear if necessary, the engine must not labour in any conditions. 

Avanti TT3 Kit Content 

Avanti Cylinder Number Piston size Ring Gap 

Cylinder Head 



4 x cylinder studs 

4 x 8mm long head nuts 

4 x 8mm flat washers 

4 x 8mm wavy washers 

2 x 7mm brass exhaust nuts 

2 x 7mm wavy exhaust washers 

1 x 7mm inlet nyloc nut 

1 x 7mm long inlet bolt 

2 x 7mm wavy washers 

2 x 5mm bolts 

2 x 5mm wavy washers 

2 x 5mm plain washers 

3 x 8mm button bolts 

3 x 8mm plain washers 

3 x 8mm wavy washers 

3 x Base gaskets (0.4mm, 0.75mm & 1.00mm) 

1 x inlet gasket 

1 x exhaust gasket 

2 x Avanti TT3 stickers 

Fitting Instructions 

Running Instructions