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Adj carb mixture.

Posted: Sat Oct 08, 2005 1:12 pm
by nicbeer
What is the correct way to adjust idle mixture and idle speed. I have found below on the net. Is this best way to do it.

""With the engine at proper operating temperature and at idle speed, turn the idle mixture screw inward (clockwise) SLOWLY until the motor starts to falter. Having turned the idle mixture screw inward until the carb falters, now back it out slowly, keeping count of the number of turns outwards until the motor begins to run smoothly. Re-adjust the idle speed set screw as necessary to maintain the RPMs about 900-1000 RPMs.

Btw it is on a Aisin toyota 4k carb.

cheers

Nic

Posted: Sun Oct 09, 2005 7:51 pm
by Loanrangie
Sounds ok, really need an analyzer to set the mixture correctly but that will get it running till you can get tuned properly.

Posted: Sun Oct 09, 2005 11:49 pm
by Gribble
Yeh thats correct, wind in the screw until the vehicle begins to stutter, slowly wind it out until the engine idles smooth agian.

It only affects your mixtures at ide, the jets control the mix with open throttle.

Posted: Tue Oct 11, 2005 10:03 pm
by 360 scout
yeh thats close enough , but on a correctly jetted carb (only idle jet I'm talking about) you can wind the screw out which enrichs the mixture until it starts to run rough or "lumpy" & Turn the screw in until it leans out or falters as mentioned above,then go half way between with the scew turns.
I usually run alittle bit on the rich side as it improves your cold starts idling etc & i always reckon the engine runs a bit cooler when richer also helps stop "run on " when you turn the key off.
be aware though most carbs the idle screw controls the amount of air fuel mix through the carb , some only control air!
so most carbs turning the screw in will lean the mixture , but some turning the screw in will actually enrichen the mixture!