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HOW TO RESOURCE: Boliy Pro3600Si Carburetor Adjustments


Boliy generators come standard-equipped with a carburetor main fuel jet designed for operation at sea level. If you will be using your generator at low altitude, the standard main jet ought to work fine.

Equipped with the standard sea-level jet, your generator will start and run at a higher elevation; however the motor will not operate at peak efficiency. Your generator motor will be what we call burning rich; in other words, the standard main fuel jet will allow too much fuel into the carburetor's air/fuel mixture.

The result of this is a heavy soot-like covering(the residue of fuel not properly burned) on the spark-plug electrodes.


If you discover this soot-like coating on plug electrodes, you will need to adjust carburetor for a different amount of fuel.

Part of this will be changing the carburetor main jet. This is not a difficult procedure, but it will entail removing the generator's back and left-side panels to access carburetor(for removal details, see BOLIY TROUBLESHOOTING--CASING).


The manufacturer offers two options for altitude tuning: the most common is a 5,000-foot main jet which accommodates many high-elevation applications. For those aiming to operate at mountainous elevations, there is an 8,500-foot main jet available.

To change main fuel jet, do as follows:

A)Unscrew hex nut on bottom of carburetor float bowl. This will allow bowl to be removed.

REMEMBER: before removing carburetor bowl, be sure that FUEL VALVE has been shut off. This will stop fuel flow from gas tank. To drain remaining fuel from bowl, loosen drain-plug screw attached to clear plastic drainage tube. Drain-plug screw does not need to be unscrewed completely for proper drainage to occur.

B)Locate fuel jet nozzle.

CAUTION: be aware that the information in most Boliy Owner's Manual about the appropriate jet to change is INCORRECT! The part described in most owner's manual(said to be located above carburetor-bowl hex nut) is the main carburetor nozzle. It does not need to be fiddled with.

The jet you want should be plainly visible on the outside of carburetor stem when bowl is removed. It is perpendicular to the hex nut which secured the bowl. In appearance, it will correspond to the replacement jets you're about to swap it with.

TIP: be careful not to mix up the different jets following removal. Telling them apart is impossible with the naked eye. In most cases you would require a microscope(not just a magnifying glass) to tell which is which.

C)Unscrew and replace the factory jet. Remember that there are two high-altitude jets, a 5,000-foot jet, and an 8,500-foot jet. Select whichever best represents the altitude at which your generator will operate.

TIP: Do not over-tighten jet. Seating it snugly is sufficient.

D)Replace fuel bowl and apply hex nut, tightening snugly.

CAUTION: to avoid fuel leakage, be sure to seat carburetor bowl properly. It is easy when replacing the bowl on this carburetor to hang it up on the flange of the aluminum carburetor body.

TIP: There is a gasket on the hex nut that secures carburetor bowl. When reattaching nut, be sure that gasket is in place to circumvent fuel leaks!

E)Turn the fuel valve ON, allowing gasoline from tank into fuel system. Motor need not be started. Check for leaks not only around carburetor bowl, but in rest of fuel line.

F)Insert clean spark plug, and start generator. Test-operate, preferably with load, for 15 to 30 minutes.


After test run, remove spark plug(should always wait to pull plug until engine has cooled), and examine again for soot. If your plug is clean, you have likely solved the richness problem by exchanging main jets. To be sure, check plug again after extended generator operation.

If your spark plug continues to collect soot, you will need to lean the fuel mixture. Here is how to do it:

TIP: Since fuel mixture may require several adjustments before it is satisfactory, you will need to check and recheck the spark plug. Each time the spark plug is fouled(covered in soot), it should be cleaned or restored to a fresh condition.

It is not a bad idea to have two plugs handy, one which can be cleaned while you test run your generator with the other!

TIP: clean your soiled spark plugs with a wire brush to restore them to their original condition.


There are three possible methods for accessing the fuel-mixture screw. We feel it is easiest to follow the instructions shown in the following photo tutorial: Boliy Fuel-Mixture Screw Photo Tutorial

TIP: if you are able, the best time to adjust the fuel mixture is with generator running. Before starting motor, familiarize yourself with location of the fuel-mixture screw.

G)With the fuel tank in position, you will need a flashlight to see the fuel-mixture screw. Lift end of tank, and shine beam into cavity between it and rear of carburetor.

The fuel-mixture screw faces upward at a 45-degree angle.

H)Use a long-bladed flathead screwdriver to reach fuel-mixture screw, and turn it two revolutions clockwise(tightening screw will lean out air/fuel mixture).

I)Start generator and run for 30 minutes, operating with ECONOMY switch both ON and OFF. Re-check plug for soot(after engine has been allowed to cool).

The soot buildup should have been reduced. If the plug is now clean, you may have solved problem. Check again after extended generator operation.

J)If soot remains, clean spark plug, turn fuel-mixture screw another two clockwise revolutions, and test. If you adhere to this procedure, you are guaranteed to correct problem.

TIP: it is possible, during adjustment, to make the fuel mixture too lean. This will be characterized by a grey-white singeing of the electrodes. If this happens, simply loosen screw one turn(counter-clockwise).

Your generator will run fine once you have achieved the approximate correct fuel mixture. Fine-tuning by small rotations of screw is probably a waste of time.

TIP: if you do choose to fine-tune, try adjusting fuel-mixture screw in increments of 50%. In other words, back off(counter-clockwise) one revolution, then if necessary, advance screw(clockwise) one-half revolution, etc.

If you are able to manipulate fuel-mixture screw with generator running, you should notice changes in the way the engine sounds. This can help you identify the approximate mixture adjustment for best operation before you begin checking spark plug to fine-tune.

REMEMBER: when making adjustments with engine running, to give engine enough time to react to new setting(try waiting for between 15 and 30 seconds following each adjustment!).


If you discover that you cannot effectively reach your fuel-mixture screw in the manner described above, then you will need to remove fuel tank. The procedure for fuel-tank removal is as follows:

K)Before pulling tank, you will need to disconnect fuel line. The best place to do this is at top of fuel filter(white and bell-shaped, located near inside of FUEL Valve).

REMEMBER: to clamp line first if there is gas inside tank. Use standard-equipped fuel-line clamp above fuel filter. Be sure clamp is secured to tightest notch to prevent leakage!

TIP: even with line clamped, leakage may occur. Position rag or paper towel to absorb draining fuel prior to disconnecting line.

L)Remove 2 screws securing fuel tank to front panel. Fuel tank should now come away.

M)Notice that fuel-tank removal allows you to easily access fuel-mixture screw(as well as idle-speed screw; SEE BELOW).

TIP: we recommend, if possible, that you make fuel-mixture(and idle speed) adjustments through cavity between tank and carburetor. It is easier to perform test runs if fuel tank does not need to be replaced prior to each.


Because it is computer-maintained, the idle speed of your Boliy generator probably will not need to be adjusted. If you do want to change idle speed, here is what to do:

N)Lift end of fuel tank, and shine a flashlight beam into cavity between fuel tank and carburetor as you did before.

You will see a piece of clear plastic tubing. The idle-speed screw is found immediately behind where this tubing connects to the carburetor.

Remember that your fuel-mixture screw faces upward at an angle. The idle-speed screw, meanwhile, will be horizontal.

Experiment to determine if you are comfortable making idle-speed adjustments from this position. If you find it too difficult, then remove fuel cell as described above.

O)If you wish to increase idle speed, rotate idle-speed screw clockwise one turn(or decrease by rotating one turn counter-clockwise). Test-operate generator. Adjust idle incrementally until you have achieved desired result.

Need Help? Call 866-613-9115
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