Here are some estimated Flow Rates for the Popular Mikuni Carburetors.

Here is a sample comparison. All test were performed at 10" of water pressure, which best simulates atmospheric conditions.

More Flow Comparisons

The MOSSBARGER 8-PETAL REED CAGE flows better and produces more power than any other reeds, cages, or any modified stock cages. This is no surprise; it was designed to do so from the start! Certainly the old saying of "NO FLOW MEANS NO GO" is very true in reed cage technology.
NOTE: "CFM"  Stands for  "CUBIC FEET per MINUTE" of Air Flow

Bigger is not always better when dealing with components of the intake system. For instance, the most common mistake, by racers, is installing a 38mm carburetor on a 250cc engine. Engine builders who tell them that the 38mm carburetor will increase rpm and top-end horsepower mislead people. Our experience is that the 38mm carburetor will kill the low-end and mid-range power due to the slowing of the air speed (velocity) in the big venturi. The 38mm will flow 129.50 CFM while the MOSSBARGER 8-PETAL REED flows only 71.40 CFM (which is more air flow than any factory or after market reed). Since the reed cage lives between the engine and the carburetor, the cage is what controls how much air will flow into the engine, not the carburetor. So why use a carburetor on an engine that cannot use that much air? The larger carburetor does not improve rpm. The only way to increase total revs is to reduce the weight of the crank, rod, piston, and wrist pin. Why then do we use the larger carburetor on 250cc engines? Is it the PARTS PEDDLERS make more money by selling the 38mm instead of the proper 36mm carburetor? Remember that a 36mm carburetor will flow more air than any 250cc engine will ever use. Always use the smaller carburetor for a higher air speed and a better mixture of the fuel and air. We recommend the following carburetor sizes for 80cc-500cc engines.

The proper racing reed cage should have as much air flow as possible, because more air flow means more go!!! Reed cages should have long narrow easy opening petals and high air speed. Reed cages should not have inserts, boosters or stuffers as they cut the air speed and kill the total air flow. Reed cages should not have wings, bars or airfoils inside the cage itself. This makes the airflow travel a longer distance that slows the speed, and they cause a severe restriction to the movement of air. The only function of the reed cage is to deliver the largest amount of air at the highest speed possible. Always remember that!! Do not believe the big fancy ads that say airflow isn't important, remember MORE FLOW = MORE GO!

When installing our reed cages, the engine will generally run" RICH" on the low end, due to the increased air/fuel flow from our more efficient design. The following jetting guide will start you off in the right direction.

1. Lower the pilot jet size by 1 or 2 sizes smaller.

2. Raise the main jet by 1 or 2 sizes larger

Note: steps 1 and 2 are very important in that, if you lean the pilot you must richen the main jet. This keeps the same amount of fuel going to the engine.

3. The pilot jet is the correct size when the engine pulls hard in the lower ranges, and runs crisp and clean.

4. The main jet is correct when the engine runs smooth and clean in the upper RPM ranges. It should not be lean, As all 2-strokes run better with a slightly richer jet setting.

Note: The sparkplug should have a DARK BROWN color on the insulator
 
 

With all racing engines, the more air you can flow into the cylinder at a high velocity, the more power can be obtained. Below are measurements of different reed valve assemblies measured at 10" of pressure drop, with all figures corrected for temperature and humidity. Note that CFM is cubic feet of air per minute.

The Mossbarger Comeback Story


MOSSBARGER RACING PRODUCTS, LLC