How do I know if my pilot jet is too rich?

If the pilot circuit is rich, the engine will have a rough idle or may not return to idle without “blipping” the throttle. You may also notice a distinct smell of raw fuel and some eye irritation from the exhaust.

How do you adjust the air fuel mixture on a Mikuni carb?

Adjust the pilot jet, located below the air screw, using the adjustable wrench. The pilot jet regulates the amount of fuel entering the carburetor. Turning the pilot jet to the right lessens the amount of fuel entering the carburetor; turning it to the left increases the amount of fuel entering the carburetor.

How do you adjust a pilot jet?

With engine running at low RPM, turn the screw in clockwise until the engine begins to stumble, then turn the screw counterclockwise until the engine stumbles, noting how many turns in/out both occurred. Now, adjust between these two settings to achieve highest RPM and smoothest running engine.

What does raising the needle jet do?

Raising the needle by lowering the chip position at the top of the needle will richen the mixture. Lowering the needle will lean the mixture. WIDE OPEN THROTTLE: Changing the MAIN JET affects this range. Select the size which offers the best wide open throttle.

Can you drill out carb jets?

By drilling out your stock main jet to larger sizes you will be able to narrow down what jet size your carburetor needs. You will need a numbered drill bit set. The brass main jets are easy to drill so you can get by with one of these inexpensive drill bit sets.

How do you adjust a carburetor pilot screw?

Start the engine and warm it up to normal operating conditions. Connect a tachometer. Adjust the idle to the required specification. Generally the pilot screw adjustment procedure involves turning the pilot screw in or out in small increments until the idle climbs as high as it will go.

What is worse running rich or lean?

Running lean can give you more power but to lean will blow your engine. Running too rich can also hurt your motor. Think of it when you are mixing gas for your weed wacker. It is always safe to add a little more oil than not enough to the mixture.

How do you adjust the carburetor on a Mikuni go kart?

The two brass jets pictured here are the main jet and pilot jet. The main jet is the large round one. Each jet can be removed with a flat blade screw driver. To adjust the jet needle position you need to unscrew the top of the carburetor. Be careful as you take the cap off because there is a spring inside.

Where is the idle jet on a Mikuni carburetor?

Sometimes the air screw and associated jet are called the slow-running screw and jet. The idle mixture is controlled by two controls: a throttle stop screw and an idle air screw. The throttle stop screw goes into the side of the carb right beside the throttle slide.

How many pilot Jets does a Mikuni have?

When we tuned our Mikuni we tried about ten different main jets, five pilot jets and every clip position on the needle jet. Our testing resulted in this final setup: 130 main jet, 12.5 pilot jet, needle clip in the center position and air screw two turns out (stock position).

What kind of CARB does a Mikuni round slide use?

All things considered, the round-slide Mikuni is an excellent carb, with a wide range of tuning capabilities. You can also find jets and parts easily. A huge number of vintage bikes come equipped with the good old round-slide Mikuni carb. In fact, just about every Japanese bike from the 60s and 70s came with this mixer.