Carburettor -YSN PHBH 30 BS- CS=34mm - without vacuum/oil connection - cable choke | Carburettors | Carburettor | Engines

Preview: Carburettor -YSN PHBH 30 BS- CS=34mm - without vacuum/oil connection - cable choke

Description

Carburetor YSN PHBH30 BS - connection width engine Ø34mm, connection width air filter Ø42mm

Reliability meets performance

The PHBH carburetors are one of the best choices when it comes to reliable and insensitive carburetors for tuned Vespa engines. Their proven design has been tested thousands of times and is suitable even for very powerful engine setups well above the 30hp mark (see also blog posts Quattrini M252). The PHBH carburetors are easy to set up and due to their popularity (stock carburetors on Aprilia, Moto Guzzi etc.) there is a wide selection of tuning, accessories as well as replacement parts.

The PHBH 30 is now available from us as a true to original replica from YSN.We have with the manufacturer YSN a very good and reliable manufacturer on the side, which continues to produce the legendary carburetors for us. The quality is absolutely comparable with the Italian original and the parts are also interchangeable to 99% (Only the gas slides are guided by a slightly longer centering pin in the carburetor. If Dell'Orto gas slides are to be used, this pin in the aluminum casting can simply be taken back a little).

We have the carburetors assembled according to our specifications and can thus offer a carburetor that is already very well pre-tuned.

The YSN 30 gets the following basic tuning from us:

Slide: 40
secondary jet: 55
Main jet: 125
Needle: X2 (needle clip on second groove from top)
Mixing tube: AS266
Float needle valve: 250
choke nozzle: 70
incl. pre-assembled cable choke

FLOAT NEEDLE VALVE
The float needle valve is optimized for use in the Vespa large frame area. Here the pressure drop between tank and carburetor is quite low so a larger float needle valve is required. With twice the size of the main jet, a very large reserve is already built in here (rule of thumb: float needle valve approx. 30% larger than the main jet). Thus, the installed float needle valve is suitable for main jet sizes up to 190.

If a fuel pump is used, no throttle piece should be used in the return to the pump or alternatively the float needle valve should be selected smaller. We do not recommend float needle valves larger than 270. The significantly heavier float needle of the large hexagonal types (from size 300) requires a different float weight to compensate. Otherwise the float level will be too high and will cause a constant enrichment of the gasoline/air mixture. This is not a problem as long as the tuning of the carburetor is adjusted accordingly and the carburetor does not overflow during operation.
Also, with a 300 size valve, the bore is already so large that, depending on the pressure differential (empty tank vs full tank), the float closes more sluggishly due to the larger pressurized needle area. This can also lead to an increase in float level and must be adjusted accordingly.

For these reasons we use the 250 size valve, which has proven to work very well on countless setups, even very powerful ones.

MIXING TUBE
We use the mixing tube type AS266. This is longer than the AV type and thus ensures a much cleaner engine running, since it does not grease the gasoline/air mixture so much in the medium speed range. We have had the best experience with this type of mixing tube in everyday use. With it, the engine can be adjusted cleanly and still be fully loaded in every range. Even load ranges otherwise considered dangerous for two-strokes (such as partial load at high rpm) can be tuned very well with this mixing tube.

NEEDLE
The X2 needle has proven itself over the years as THE all-round needle par excellence. In former times often and gladly combined with the mixing tube type AV264 it is in connection with our AS266 a very good needle for 99% of all engine setups. As a rule, the use of the needle on the position as delivered is very good drivable. If you initially want to make the engine run richer in the partial load range you can set the needle clip to the third notch (counted from the top). This will make the engine significantly fatter in the middle.

MAIN NOZZLE
Today, with modern electronic helpers, you can get a good help in tuning the engine. For example, EGT (Exhaust Gas Temperature) and AFR (Air Fuel Ratio = Lambda) can give very good information about the quality of the jetting. As a rule, many engines are tuned significantly too rich for fear of engine damage under full load. It is seldom a too lean fueling that leads to engine damage, but rather a too high compression, secondary air or an ignition setting that does not match the engine (especially with dynamically adjusting ignition, the partial load range often has a too large pre-ignition angle). The main jet we use in the carburetor in size 125 is an ideal starting point for engine setups from 177-221ccm on rotary valve basis. Engines with intake control via a diaphragm intake usually require a larger main jet (135-145).

KABELCHOKE
We have the YSN PHBH 30 equipped with a cable choke instead of a flip choke. This allows the choke to be conveniently operated via the choke knob on the frame, just like the stock carburetor. All that is needed is a new choke cable. An ideal combination for the PX models is the hollow choke knob. Here, the choke cable can be fed through the knob and is then screwed tightly by means of a grub screw.

SUMMARY: Excellent reproduction of a carburetor legend. Convincing in workmanship as well as function and here equipped with a very good basic tuning.

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€84.89 *

incl. VAT plus shipping costs

Available immediately (delivery time 1-3 working days*)

P For this item you get fidelity point/s

OEM numbers (for comparison purposes only)
Dellorto	03302

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