Reply With QuoteAre you talking about jetting or setting the idle mixture screws and idle speed?
i have two demon 750 carbs on my motor. they are due for a good tuning and need to be adjusted. i havent messed with carbs to much, should i take them to a shop to be syncronized and adjusted properly? any good tips or online info that might give me what i need? the boat runs really good but i know its not running as clean as it could. thanks
Are you talking about jetting or setting the idle mixture screws and idle speed?
id like to have them tuned as best as posible including jetting. i know a dyno tune is the best answer but i would just like to get it running a little cleaner. float level, butterflies adjusted, any other tips. i know this is kind of broad, but just figured id ask before spending the money somewhere.
First off, the float level has to be right. On a Holley carb they're super easy to set. There's a sight plug screw on the side of the bowl...you remove that, then adjust the float so that the fuel level comes up to the bottom of that sight plug hole.
The idle mixture screws are to adjust your idle fuel mixture and they only work at idle. When the butterflies are closed, there's not enough vaccuum on the top side of the butterflies to pull fuel from the bowl, so the carb has idle mixture ports that trickle fuel into the motor when the butterflies are closed. How much fuel is controlled by the idle mixture screws.
The "jets" in the carburetor control your cruise fuel mixture, and you have to know how to read your spark plugs to know whether you're running the correct size jets to give you the correct fuel mixture.
When in doubt always err on the side of rich. You'll burn more fuel that way, but if you're too lean the motor will run really hot and you can burn shit up that way.
The first steps should be replacing your fuel filter, and a cleaning and rebuild by a reputable carb shop. Only clean, air and fuel tight carbs will accept a tune to begin with.
Save yourself a lot of grief, have a pro tune it after the carbs and fuel filter are done. I also reccomend you have him install a gauge and check the fuel pressure out.
Knowing a little about (AKA)Holley's is akin to knowing a little about sky diving. A tuner will make it look easy, and you'll learn something, so at least you can effectively discuss problems in the future.
You should learn to do it yourself. Vacuum guage, and /or wideband O2 sensor tuning, it's your hot boat, fix it.
Demon can help you acquaint yourself with their product, but if you want it right, LEARN HOW.
BG has the float level sight level windows.
How old? Do they NEED rebuilding, or is it a TUNING issue?
Keep in mind that the float level needs to be set with the carb(s) level or it will be an inaccurate setting...ie sloped away from the sight plug will cause you to set it too high and vice versa.
Just my 2 cents
Keep in mind that the float level needs to be set with the carb(s) level or it will be an inaccurate setting...
Actually they should be set with the boat at it's riding attitude, carb's are usually not level at that time!..
Actually they should be set with the boat at it's riding attitude, carb's are usually not level at that time!..
Yeah, I may have phrased that wrong. I was just trying to point out that it shouldn't be on the trailer with one tire in a pot hole and the other not...
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