Readers ask: Where To Buy High Altitude Carburetor Jet?

What size jet for high altitude?

For elevations above 2,000 feet but below 10,000 feet (610 to 3,048 meters), use the first size smaller jet. For elevations above 10,000 feet, the second smaller jet should be used.

How to jet for high altitude?

The general rule for jetting is to drop one main jet size for every 2,000 feet of elevation increase. You can also go one clip position leaner on the needle jet. This is a good start for high-altitude adventuring, but depending on the temperature and humidity, you may need to go leaner or a touch richer.

Does elevation affect a carburetor?

Power goes down with higher altitude.” For small changes in altitude, carburetors will compensate without any modifications. That can change the amount of fuel to the engine – more fuel pressure for lower altitude and less fuel pressure for higher altitude.

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What happens if main jet is too big?

For example, using too large of a main jet will cause more fuel to enter the combustion chamber than it can efficiently burn. This will result in a “sputter” at full throttle. It could best be described as a rapid misfire.

What happens if main jet is too small?

Be careful: most engine jams occur when the main jet is too small. A lean fuel/air mixture will cause the engine to overheat fast.

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

If the bike surges or hunts, the pilot jet is probably too small (lean). Other indications that the pilot circuit is lean are popping or spitting through the carburetor when the throttle is opened and popping or backfiring through the exhaust when the throttle is shut.

How do I know my main jet size?

Consult your manual first to find the stock size. Also pay attention to the numbers on the side of your old jets, which you’ll be able to see in the steps to come. A larger jet number means a bigger hole and more fuel. A smaller jet number has smaller holes and should be used if your engine needs to run more lean.

How do you adjust air fuel mixture screws?

Turn the screw clockwise until the engine starts to sound rough.

  1. Tightening the screw weakens the air and fuel mixture and decreases the amount of fuel flowing to the engine.
  2. Tightening the screw is also called making the fuel mixture leaner, which lowers the RPMs at which the engine idles.
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How much horsepower do you lose at altitude?

Generally speaking, an engine loses three percent of its rated power for every 1,000 feet of altitude gained. This means you could lose as much as 20% of your vehicle’s horsepower if you drive it from sea level to Big Bear Lake (with its 6,750 elevation).

Why do cars overheat at high altitude?

When driving at high altitudes, remember the following: Thin mountain air can affect your car’s engine and diminish your acceleration and climbing power. The potential for overheating is greater. The potential for vapor locks is greater.

What happens to the air fuel mixture ratio when the altitude is increased?

Carburetors are normally calibrated at sea-level air pressure where the correct fuel-air mixture ratio is established with the mixture control set in the FULL RICH position. However, as altitude increases, the density of air entering the carburetor decreases, while the density of the fuel remains the same.

Do engines run rich at altitude?

One of the more surprising outside factors that influence engine performance, is altitude. As you rise above sea level, air density decreases, meaning there’s less oxygen in the mix on the intake. This will cause an engine to run rich and/or lose power.

Does altitude affect oil pressure?

Oil pressure should be the same at altitude. The pressure relief valve that controls oil pressure is referenced to ambient pressure and therefore maintains constant gauge pressure not absolute.

What does a slow jet do in a carb?

The carburetor’s job is to precisely and repeatedly deliver the appropriate amount of fuel to the engine throughout its entire speed and load range. To do this, carburetors utilize several different circuits that control different parts of the speed/load range of the engine.

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