2. Installation preparation

Assembly manual


Richard Taylor wrote this manual.

This installation will greatly increase the performance of your standard Lambretta engine. It is advisable that you check or replace the main bearings & oils seals before installation. If you intend to use an expansion chamber it is
highly advisable to install a GP crank & electronic ignition. With all installations the crank taper, key-way, big end bearing & con rod MUST all be in excellent condition. The crank must also be straight and true, this is a professional
job and requires specialist equipment.

All small block Lambretta engines are suitable for GT186Kit. GT200 Big Block kit are suitable for all Lambretta big block casings.

All ignition systems must be reliable and timed accurately to 19 degrees BTDC (2mm BTDC with 58mm stroke and 107mm rod), electronic ignition is preferable. Barrel studs & threads must be in good condition. Gear selectors, clutch and chain must also be in good condition. Series 1 & 2 cranks with plain bush small-end bearings must not be used.

Kit contains the following parts:
1pcs Cast iron barrel
1pcs Piston, rings, pin & circlips
4pcs M6 SS cap head bolts, spring washers and plain washers
1pcs Inboard reed valve gasket
1pcs Outboard reed valve gasket
1pcs Reed valve
1pcs Inlet manifold, 25mm, 30mm or 34mm
1pcs Wide small end bearing
1pcs Porcupine cylinder head (option)
1pcs Carb kit (option)

In addition to the kit you will need:
1. Good tools & a quality 5mm ball end hex socket key.
2. 2pcs M7 exhaust studs, nuts and washers
3. Suitable carburettor & cable choke conversion
4. Suitable base & head gasket and or silicon sealant
5. Big bore exhaust gasket
6. Suitable exhaust (42mm clubman or better)
7. Suitably profiled cylinder head
If your engine has not been removed from the scooter
prepare your scooter for installation in the following way:
1. Remove foot boards on both sides
2. Remove bump stop & rear shock absorber
3. Remove carburettor
4. Remove exhaust and head cowling
5. Remove cylinder head, barrel and piston
6. Clean base gasket area, removing old gasket and dirt

Section index

1. Pre-fitting kit preparation
2. Installation preparation
3. GT186 Stock Touring Installation steps
4. Air box installation amendments
5. Carburettors, jetting & sparkplugs
6. Running in
7. Care and Maintenance
8. Tuning & performance
9. Disclaimer
10. Trouble shooting
11. Cylinder head specifications
12. Suggested specifications