air/fuel

so today I went for about a 10 mile ride to my son's baseball game, went pretty well, until i ran out of gas, (i gotta get used to no gas guage), when i got home, before turning off the motor, i played with the air/fuel mixture screws, i think they are also called pilot screws, to see if things would change, as i slowly turned the screws, absolutely onothing changed with regard to the rpm's same thing on the other carb, anybody got any idea what this is all about, the bike rides pretty well at 55-60, but when i hit a small hill, i have to downshift to not loose to much speed on the fourlane, i was thinking that maybe adjusting the air/fuel mix mightmake it better, but as i said, turning the screws did diddy to change rpm's, thanks in advance. :whistle: oh yeah it is a 1979 kz 750 two cylinder, bone stock

jacksdad wrote: ...ran out of gas....

Should run with petcock set in ON position which allows switching to RES (reserve) position when fuel level gets low. Then it's time to fill up.

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Good Fortune!

no worries, thanks for the info on the signature. i just changed it

SO WAHT DO YA'LL THINK ABOUT THE AIR/FUEL MIX?

Changing the air fuel mixture screws only affects the idle mixture, and barely the cruise position of the throttle, everything after that (accelleration), uses different parts of the carburetors.

The mixture screws should be set at specific points with calibration equipment like a colortune plug, or a vacuum guage, etc.

If everything is stock on your bike (intake/exhaust), then set your screws back to stock (around 1-1/2 turns out from lightly seated), and be done with them.

To get more power out of your machine, you'll need to start reading up on tuning: Jetting, timing, plug temp, etc.

Good luck.

It won't change the idle, just richens the mixture. after adjusting go for a ride and check your plugs to see how they are burning. You want a light tan color.

oh well, i guess i learned something today after all, i will pull the plugs tommorow to see what they look like, thanks guys

dshelly wrote: It won't change the idle, just richens the mixture. after adjusting go for a ride and check your plugs to see how they are burning. You want a light tan color.

:blink: It can affect the idle greatly. In order to check that particular carburetor circuit you would require a proper plug chop after many miles of cruising ONLY, and light tan is not what you're looking for from that throttle position.