Introduction: The carburettor is essential on the 2-stroke engine, this is why the RRD team has decided to sell only genuine INC certified jets - engraved by DELLORTO certainly more expensive but it has been proven by various tests that the jets (adaptable, copies…) create a loss of power, bad starts, age badly, offer bad performances, the numbers are sometimes illegible, a bad machining adapting badly to the shapes of needles… The real dellorto jets are all engraved INC, proof of quality, resistance and performance. They use a precise machining scheme, the best metals and the best machines. Thank you for your understanding. We recommend adjusting the engine only once it has been run in because you have to accelerate fully and push the engine into the revs. For running in, it is better to go a little bigger in order to lubricate the engine well.
Description: The main jet comes into action all the time except at idle, it is its size which defines the quantity of gasoline which will mix with the air, which will give in the carburettor: the gaseous mixture, of course, a carburettor bigger makes it possible to take in more air, therefore to mount a bigger jet and therefore, more gas mixture = better filling and more performance. Ditto for the air filter, filter taking more air = larger nozzle and therefore more gas mixture for more performance. These small pitch jets are mounted on Dellorto (DELL'ORTO) carburettors: PHBD, PHBE, PHBG, PHBH, PHCF, PHF, PHM, PHSB, SHA, SHB 16, SHBA, SHBC, VHSA, VHSBAttention, exceptions exist! And on some of the carburettors mentioned, this jet is used as a secondary/idle jet! The setting of the jet is essential in the setting of an engine, it is it that will determine your power and longevity. As soon as you change any part, you have to check its settings. To be able to adjust, you will first have to adjust the idle jet, then adjust the mixture: fully tighten the mixture screw (with great moderation) then loosen it by 1.5 turns or even ¼ turns. For the needle it is necessary to trivially notch towards the middle. Then start with a normal jet and a cold type spark plug in NGK B8 or B9, DENSO / MALOSSI W27 or even origin for tests. We can never repeat enough that spark plugs that are too cold, type B10, do not offer good enough self-cleaning to quickly and correctly perform carburetion adjustments! Surroundings: phbg 15 start with a 80 jet phbg 17.5 start with a 85 jet phbg 19 start with a 90 jet phbg 21 start with a 100 jet...It varies depending on the airbox, engine, horn ... So, as a general rule, new carburettors are delivered with the appropriate jet at the start. After your short test drive, check the color of your spark plug.
WHITE OR GRAY = Jet too small because the engine takes in too much air and too little fuel: risk of tightening
BRICK / BROWN / CHOCOLATE / ORANGE = excellent gas mixture / longevity and power, note, a liquid-cooled aluminum engine allows a more efficient and very explosive mixture with a light orange spark plug, while a cast iron engine, air-cooled , requires turning fatter with a red color candle that turns black!
BLACK/GRAS = Jet too big: risk of sticking / loss of power
