Carburettors & Exhausts

Carburettors and exhausts can be one of the most important factors when building your Lambretta for power, performance and reliability.

Exhausts are the biggest controlling factor on any two stroke engine, and can affect many aspects of you scooter, not just speed. A badly matched exhaust to your set up could loose you power, cause heat build up / seizures, affect fuel consumption amongst other things.
We have tried almost all exhausts on the market, and after many tests on our various scooters we only sell the ones we are happy with in terms of performance and quality. There are many exhausts out there on the market, and many work in differing ways, some made very well, some poorly made, some work well, some kill your scooter both in terms of speed and reliability.

CLW recommend three types of performance exhausts.

Ancillotti this is a box pipe, by that we mean if you look at the original Lambretta S3 exhausts, they have an oblong exhaust, a box shape. The Ancilotti makes good low down power, but also does rev on a fair bit more then Clubman or big bore type exhausts. Although the exhaust does give good power, because of its original box design, it is not as efficient as an expansion type exhaust, but it is ideal for keeping original type looks. Delivers its power low down, and is ideal for a touring set up.
JL3 / JL Road. Works in exactly the same way as the above Ancillotti, but gives you more power. An expansion exhaust is without doubt the easiest way to gain power and speed, of course as long as its a good exhaust!. Available in straight stick out design, or curly design, where the exhaust tucks back underneath. There is no adverse affect to ground clearance on the curly pipe. Peak power is made from around 3 to 4,000 rpm, up to around 7,000 and is ideal as a touring / cruising type set up.
CLW Race. is an exhaust that allows more power and revs. How ever this is made higher up in the power band, and thus although you get more power and speed, this would be in a form of a power band that tends to start at about 6,700rpm, and continue to 9 to 10,000, ideal for a fun racing around on type power delivery. Available in straight stick out design, or curly design, where the exhaust tucks back underneath, and as with the road version there is no adverse affect to ground clearance on the curly pipe.

Carburettors
Choosing the correct size of carburettor for your set up is not as vital and jetting the one you do choose correctly. Equally the air induction is a very important factor, we all fit fast flow fuel taps, but totally neglect the air intake. The original air intake system on a Lambretta is very restrictive when you start to push the performance of your Lambretta. Think of the air box as a storage box for air, it simplyholdnot large enough to holf the volume of air a well tuned engine needs. Sure you can make it work and run well, but you are restricting your performance. By far the best choice of filter on tuned scooters is our remote air filter option, this have been carefully designed not only with excellent materials for the free flow of air, but to give a large enough volume area to give the best possible performance.
Roughly speaking we recommend the following carburettors

175 / SR / Mugello

Original looks if you want to keep the original looks, best option is the SH22, or 22mm Jetex, but use a high flow filter in the air box.
Modern carb but still run it through the air box, PHBL 25mm. Although this type of carburettor does not give any more performance over an SH2/Jetex, it is a good modern replacement for worn carburettors.
Best performance with Ancilotti or clubman type exhaust we would recommend the PHBH 26mm carburettor. Although this can be made to run through an air box, in truth it is a waste of time as the large size of the carburettor body makes this more awkward. The larger body of carb is much better suited to being run through our matched remote air filter system, as this provides much better air flow thus giving better performance. The difference between running through the air box, and one of our remote filters can be 1-3hp depending on your set up.
Best performance with an expansion exhaust we would recommend the PHBH 30mm carburettor. For the ultimate gain in performance you would use the PHBH powerjet. Please read the text in the bullet above regarding running the larger PHBH through an air box, or remote filter system

Rapido / Imola / Monza kits,

Best performance with Ancilotti 30mm Dell'Orto PHBH
Best performance with an expansion Dell'Orto PHBH 30mm, or for the ultimate gain in performance you would use the PHBH powerjet.

The most common question we are asked day in day out is what jetting do I need in my carburettor!

In a recent survey of telephone calls to our shop in one day, 65% of calls were about jetting a carburettor. Of these, a staggering 43% were from people who hadnt brought their cylinder kit, carb, or exhaust from us! We give full fitting, set up , and running in details with all our kits!

Whilst we dont mind helping, it is our passion, and what we are here for after all, giving help and advice on other shops products and items is putting a strain on us helping our customers! Just think before you buy, ask the shop questions before you buy, if they dont sound helpful when they want your money, what chance have you when they have got your money! Can you even pick up a phone and ask some far away shops? No? I wonder why!

Please note we work with Dell'Orto SH, PHBH carburettors, standard, Ancillotti / Clubman / Big bore, JL3 & JL4 exhaust systems, Imola, Monza and Mugello cylinder kits. This is what we sell, fit and recommend, if you choose to purchase other suppliers or manufacturers parts, e.g exhausts, it is not really worth asking us as we do not have experience with such items to be able to know what jets/timing/set up to suggest.

Point of interest no two scooters are ever the same, so jetting wont be either! We run THREE Imola kitted scooters within the staff, guess what? All three run different jetting!!

Jetting is vital to power, reliability, and enjoyability (probably not a real word, but I bet you understood it!) for your scooter. Jetting a carburettor is THE single hardest job in setting up your scooter. Most of us can easily build an engine, match a cylinder to the casing, but by far the hardest job to perfect is jetting.

Whilst we will try to help and give advice, we are very much restricted, as only you know where your scooter is rich, where it is lean. This can only really be done by riding it, listening to it, knowing the vital signs, feeling how it responds and reading your spark plug. If you cannot do this, then the chances of us being able to do so over e-mail or the phone is very limited.
The best answer we can give is dyno, a modern dyno with a skilled operator can work wonders for your scooter. You could easily spend £40 to £60 on different needles, atomisers, slides, jets to set your carburettor, most of which you will fit try,and move on to the next one. When you consider this is around the cost of a session on a dyno, it makes more sense to have your scooter set up professionally.

Badly set up scooters will do any of the following

Loose power
Run hot
Run lean
Pink
Hole a piston
Gum rings
Sieze a piston
Affect fuel consumption
Smoke
fowl spark plugs
Cause premature failure of exhausts
STOP YOU ENJOYING YOUR SCOOTER

With any of our kits we offer FULL fitting instructions, including what we suggest as initial set up details, our carburettors come with full instructions on how to set the carburettor up should you want to try to do this yourself.

Whilst we will always try to help, the first question we will ask you is have you read these instructions that are available on our downloads page>

You need a basic understanding of what is going on for us to help you.