LAMBRETTA RB 20- 200cc cylinder kit ---AS USED IN THE  BRITISH SCOOTER SPORT RACING -PRODUCTION CLASS -BSSO 

Including piston kit, cylinder,  , reed valve assembly gaskets,

"DOES NOT INCLUDE  CYLINDER HEAD    AVAILABLE SEPERATE"

Fits all 125/150/175 engine casings---

Requires hi load GP 58mm crankshaft with 115/116mm conrod---

To fit this you will also need hi load bearings, electronic ignition, 28mm upwards carb,  RB exhaust system race or tourer, heavy duty 5 /6plate clutch , etc---

Don’t also forget to upgrade your brakes and suspension----

*AF RECOMMENDS*

To ensure our customers get the best out of this new kit, both in terms of performance and reliability we recommend that only experienced mechanics fit these kits, and that customers follow the advice given by their local dealers.--- We have full confidence that the RB20 offers a fantastic level of performance with a sublime power delivery ideally suited to those customers who want a fast road Lambretta that is a pleasure to ride with others, but can also provide that adrenaline-fuelled grin when the throttle is wound open..

Recommended Minimum Engine Spec.
Based on a brand new GP 150 Engine the following is the minimum engine specification required to reliably run the RB20. Cutting corners will result in greater expense and possibly life threatening failure. This is a high performance kit not for the foolish or faint hearted.
RB20 Kit, RB20 Head, RB AF 58mm Race Crank with 116mm rod, Machined Crownwheel, GT Clutch Springs, Centre Spring and quality clutch plates, Aluminium Top Chain Guide, possibly a Strong Selector Spring. This kit should only be run with an appropriate Expansion System and Suitable Open Carb, we recommend our RB Rally NK Expansion or our RB Road Race NK Expansion and the 34mm VHSB Dellorto or the 30mm VHSH Dellorto.

The engine should be thoroughly checked to ensure it has no other problems with repairs and replacement components fitted as required. The crankshaft is especially important. We can up-rate some existing crankshafts with a special 15 roller big end bearing and replacement 116mm rod or supply a complete replacement RB20 AF Race Crank with 116mm rod that has been developed specifically for the kit. Check rotation of crank in your casing before fitting the kit, some may require a small amount of filing at the top and bottom of the crankcase mouth to prevent the big end fouling on the casing.

Plug and Oil mixture
Run the machine using a Champion N2 plug with 30 thou plug gap, or equivalent from another manufacturer, you may need the hotter N3 in winter. Use a petrol to oil mixture of 25 : 1 (4%, or two AF mixing jugs per 5 litres). Never drop below 4% mixture regardless of brand of oil or what “your mate said”!
Always use 99RON Unleaded if the head has been skimmed to a higher compression. Regular 95 RON unleaded should be okay with the standard RB20 Head.

N.B. Do not fit an inline fuel filter. This jetting is not suitable for running with an air filter.

Expansion System and Gearbox
The expansion system you use will affect the final drive ratio you will need, and the desired final drive ratio will dictate which front sprocket, and crownwheel you will need to make your gearbox work well. Ask the supplier of your expansion system what they recommend letting them know your weight, if you are using the bike two up and the area you will be riding the bike in, i.e. Hilly, Flat, Town, etc.

RB Road Race NK Expansion with a 12 stone rider for fast ‘A’ Road riding we recommend a final drive of 4.8 (Li150 gearbox = 17T – 48T with 82 chain).

Chassis, Forks, Brakes, Tyres and Suspension