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Vespa Si carburetor air mixture adjustment screw

Vespa Carburettor SI Short Air Mixture Adjusting Screw SI Carburettor Dell'Orto & Spaco

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Vespa Conversion mixture adjusting screw bgm PRO for SI carburettors Dell'Orto & Spaco

Mixture adjusting screw bgm PRO for conversion of Dell'Orto SI carburettors with long hexagon mixture adjusting screw to short slotted screw. This bgm PRO conversion air mixture adjustment screw is used to use carburettors with long hexagon mixture adjusting screw also in older engines (with stud bolts for carburettor mounting). It replaces the too long adjustment screw on new Spaco and Dell'Orto SI carburettors and allows a trouble-free installation of the carburettor. Due to the shorter screw, the carburettor bowl can be left original! Fits all carburettors with long hexagonal mixture adjustment screw. (Used ex works in PX models from approx. 1989 and all new Dell'Orto / Spaco SI carburettors)

Vespa SI carburetor air mixture adjusting screw bgm PRO, short- SI20 SI24 Dell'Orto Spaco

Carburettor air mixture adjustment screw too long?

A carburettor is also a wearing part and sometimes it is simply not enough to clean a carburettor, you need a new one. Especially if you want a bit more power and adjust your engine setup, you usually need a new, bigger carburetor. Below you will find instructions on how to install the SI carburettor. Vespa SI carburetor

SI Carburettor for Vespa

Today all new carburettors come from SPACO, even if it says Dell'Orto on it. New SI carburettors, whether from Dell'Orto or Spaco, are always supplied with a long (brass-colored) hexagonal mixture adjustment cap. The exception is our bgm PRO Faster Flow carburettors - but more on that below.

Problem with too long air mixture adjusting screw

For carburettor sumps for engines without separate lubrication, this presents us with a bit of a problem, because:

  • the carburettors no longer fit properly in the swamp
  • if you have somehow managed to get it in, there is no longer a rubber seal on it
  • and it is difficult to get at it

With the mixture adjustment screw too long, it looks like this:

And this is how it should actually look:

bgm PRO conversion air mixture adjustment screw

Now you could get the idea and simply screw the old, short air mixture screw into the nine carburettor. Unfortunately this does not work, because the threads of the new Lusso carburettors are different. Please do not try to force it, the different thread pitch will destroy the fine thread in the new carburetor and make tuning impossible. Our conversion screw provides a remedy: With our short mixture adjustment screw for slotted screwdrivers you can solve the problem cheaply, easily and quickly.

Buy short mixture adjustment screw here

bgm Faster Flow carburettor

Alternatively, you can use a bgm Faster Flow carb urettor directly if you are already ordering a new one anyway, here we have already provided the update. The bgm carburettors come, for the models without separate lubrication, directly with the short conversion screw. bgm Faster Flow carburetor

Carburettor installation tutorial

Vespa PX tutorial SI carburetor bgm assembly Scooter Center

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bgm PRO FASTER FLOW Vespa Dellorto / Spaco SI 24-26 carburettors

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bgm PRO FASTER FLOW SI carburettor for the fast Vespa

The SI carburetor series is a million proven design with great potential.

Especially in the last few years, the carburetors are due to their compact design and short suction paths has also become more popular again on performance-enhanced engines.

Buy Vespa Faster Flow carburetors here

With an increase in engine performance the nozzles in the carburetor must also be adjusted. With the current engine concepts, main jets larger than 140 are not uncommon. To a uninterrupted fuel supply with larger main jets To ensure that the carburettor has to be processed quite laboriously or our finished carburettors have to be used:

PRO FASTER FLOW SI carburetor

SI FASTER FLOW tuning carburetor for Vespa

We can offer you the optimally finished carburettor for your engine project. So you keep the original SI carburetor as a backup and get a professionally tuned carburetor. You can find ours here PRO FASTER FLOW SI carburetor

Safe and fast on the go without losing weight

With the optimized bgm PRO Faster Flow carburetor you can also Achievements well over 20 hp with continuous full throttle drive without losing weight or other problems.

Carburettor already finished
In order to ensure an uninterrupted fuel supply with larger main nozzles, the carburetor must be processed in a very complex way or our ready-made carburetors must be used straight away:
Buy Vespa Faster Flow carburetors here

Details on the optimized 26 SI carburetors

With our carburetor tuning Float chamber cover, nozzle holder and holes professionally edited.

In detail, the hole for the float needle is enlarged to 2,8mm and the guide for the float needle is provided with two additional holes for faster fuel supply.

 

Faster Flow float hole

 

Important: The sealing surface of the float needle seat is restored with a tool made after drilling.

 

SI Faster Flow float valve

 

Fine tuning: The float level is checked and set to 32mm.

 

SI Faster Flow 029

 

The 5,2mm float needle is spring-loaded and helps the float needle to have a longer service life - it has to interrupt the flow of fuel several thousand times an hour and then release it again.

 

SI Faster Flow 042

Fast and constant spray supply up to 180 main nozzle

The enlarged valve bore In the float needle seat and through the additional holes in the guide for the float needle, the fuel flows in unhindered. This means that the fuel level in the float chamber remains constant.

So that the fuel can flow sufficiently quickly to the nozzle assembly, the bore from the float chamber to the nozzle assembly is enlarged from 1,2mm to 1,8mm. This diameter is with a 180 Dellorto main jet equate - this nozzle size can also be used if required.

We are currently not aware of any engines that require a main jet in the region around 180. The Fasterflow therefore still offers reserves in this area.

Touring setup with 25HP with main jet up to 160

In current touring engines with approx. 20-25PS, main jets in the range of 135-160 are often used.

SI Faster Flow 040

Leaning during the acceleration phase or swallowing due to lack of fuel during load changes are a thing of the past with the right nozzle equipment.

25s are the better 26s SI carburettors

On closer inspection you will find that the carburetor marked as 26/26 has an effective bore of 25mm.

SI Faster Flow 041

 

Vespa SI carburettor with a bore of real 26mm are prone to premature, high wear in the area of ​​the slide guide. Once this sensitive area is worn out, the carburetor is unusable.

Due to the small overlap of slide and guide with a 26mm bore, additional air can cheat past the slide in the worn areas of the guide and strongly influence the running smoothness of the engine.

This goes up to the involuntary revving up while idling and noticeable emaciation or lean jerking when accelerating.

Therefore the bgm PRO 26er SI - carburettors are provided with an optimal effective bore of 25mm.

Tip: bgm PRO Faster Flow fuel tap

Together with our bgm PRO Faster Flow fuel tap the revised carburettors are a perfect system for a reliable fuel supply.

Vespa fuel tap - the original! Vespa tuning fuel tap bgm Faster Flow

faster flow petrol tap vespa

Si tuning carburetor Vespa
The current version of the Fasterflow carburetor with 25mm is an inconspicuous and permanent companion for many kilometers. The wear of the slide guide is reduced to the possible minimum by a larger overlap.
Buy Vespa Faster Flow carburetors here

 

 

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