DIY of Air / Fuel Mixture?

**AcidBurn** · July 20th, 2007 10:05 AM

Mga bro,

Saan ba makikita ang inaadjust para sa A/F mixture at ano ba itusra nun...parang screw na may spring ba na malapit sa karburador?

How to DIY ang pag-adjust ng A/F mixture?
1) Pano ang pihit kung gusto kong bawasan ang pasok ng gaso?
Kung nakaharap ako sa auto, pakaliwa ba o pakanan ang pihit para mabawasan ang pasok ng gasolina?
2) Pano ko malaman kung nasa tamang timpla na ng hangin at gasolina?

Madalas kasi magcarbon ang plugs ko, some says na rich in fuel kaya nagkakaganun

Stanza ang auto ko, carb type.

Thanks

**fourtheboys96** · July 20th, 2007 11:19 AM

bru,

as per memorandum of the moderators, you can use the search function to look for answers to your question.

i am sure you can find some threads that can answer your air/fuel mixture question.

peace!

**gonzo** · July 20th, 2007 10:00 PM

Wala bang help desk tapos post na lang ang link?

minsan tamad na rin ako mag hanap sa mga old thread.

**rion** · July 20th, 2007 11:48 PM

Gusto ko din malaman to, peru eto lang yung thread na nakita ko...

http://tsikot.yehey.com/forums/showt...r+Fuel+Mixture

I'm not so surprised most tsikot racers don't want to share their personal experience...

**Asus700** · July 21st, 2007 05:53 PM

that is the screw usually located at the back of the carb.

clockwise po if you want a lean mixture (bawas gas) and counter clock wise if you want to a rich mixture (mas maraming gas).

to eliminate guesswork, you can go to your nearest emission testing center and makiusap ka sa attendant na isalang ang ride mo for emission, bigyan mo na lang ng pangmeryenda. co and hc reading will tell you if your mixture is good or not.

it should not exceed the minimum passing rate nila. pag mataas ang reading just fiddle with the said screw while looking at the machine output until you get the right mixture.

just make sure that the emission test center you go to has a properly calibrated machine.

HTH

**wildthing** · July 22nd, 2007 03:17 AM

I posted this way back in 2004 in this thread -

http://tsikot.yehey.com/forums/showt...burator+tuning

edited a few info (those in red are currently added)...

Originally Posted by wildthing

Most high fuel consumption are due to different origin and not an A/F mix problem...mostly driving habits, wrong rpm shift (kaya maganda sana meron kang tachometer in case you don't have one), busted engine (maybe one or 2 pistons have loose compression, etc), low grade fuel, busted plugs, busted ignition coil, wala sa tune-up, madumi ang air-filter, air-filter is sucking hot air due to lack of insulation ng exhaust (that is why Cold Air Intake works), and having a big engine (1600 or 1800cc) just to name a few reasons.

In case that you feel it is the carb A/F mix then this is my opinion:

I don't think kailangan mo pang alisin ang airfilter cover. Is that a solex? There are usually 2 main screws for adjustment - one for idling and the other is A/F. Since these 2 main screws are usually ginagalaw, it has to be easily accessible.

The idling screw is for attaining the right RPM as specified by your engine (do you have this info?).

The A/F is a bit tricky.

For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7 times the mass of air to fuel. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture - given perfect (ideal) "test" fuel (gasoline consisting of solely n-heptane and iso-octane) - quoted from wikipedia

so don't be surprised that A/F will varry from gasoline brands or mix and altitude of location where the car is running.

CAUTION FOR FIRST TIMERS:
ALWAYS REMEMBER THE POSITION OF THE ORIGINAL AND THE NUMBER OF TURNS YOU DID TO GO BACK TO THE ORIGINAL SETTING THAT YOU HAVE NOW.

Here goes, I would run the engine at the right RPM (adjust the idling if needed and preferably you should have a tachometer). When it is on a normal warmed up engine temp na. I would begin the changes.

I would then turn the A/F screw clockwise to close it (give less fuel)...I'd do this slowly....the point of close would make the engine die taking note the number of turns that you did. When the engine die (if it does not die, your idling must be high)....I will then re-turn the screw counter clockwise back to the orig setting (you did remember the number of turns right?!?).

Restart the engine....it should start like the original status.

Next step is that I would open the A/F (this time counter clock wise. Same method...count the turns until the engine choke to death due to high fuel.

Re-turn to original position and re-start. You should also not have a problem re-starting it.

Add the 2 number or turns. Calculate the 2/3rds' turn from the lean (dies due to lack of fuel) this is the theoretical stoichiometric mix of my gasoline.

wikipedia list different stoich for different fuels thus adding ethanol in your fuel tank or using LPG will require you to change the A/F mixture to ensure good fuel combustion - http://en.wikipedia.org/wiki/Stoichi...f_common_fuels

Hope hindi ito malabo o nakakagulo.

From that stoich mix....your engine is maximizing A/F mixture. You can turn clockwise to make it a bit lean, but this would hurt your power needs in case of overtaking.

Theoretically the stoich mix is really the best set-up. Chances are, your current set-up is just right or just a bit rich.

Before I end it, most engine problems (includine high fuel consumption) is not carburator or A/F ratio related...if you take into account all causes, about 15-20% lang probability ang carb or A/F ratio ang origin ng problema.

I could be wrong too you. The above was base on my experience (I am just a DIYer and not a mechanic by profession) and it works for me.

my 2 cents. peace.

**jazcker** · November 3rd, 2007 11:36 PM

i should try this i one. sobra lakas ko sa gas ngayon. dati yun 12 liters ko can reach up to 120kms or more. ngayon 60 to 80kms na lang.

**wildthing** · November 4th, 2007 12:52 AM

before trying it out...try to do a compression check ng oto mo. pagmay singaw at merun ng sira ang piston, lumalakas din ang consumption --- this is assuming that you don't change any of your driving habits nuon at ngayon.

note that if paglagi ka ring natatrapik or running on idle ang sasakyan pumapangit din ang fuel consumption

**jazcker** · November 4th, 2007 02:03 AM

Originally Posted by wildthing

before trying it out...try to do a compression check ng oto mo. pagmay singaw at merun ng sira ang piston, lumalakas din ang consumption --- this is assuming that you don't change any of your driving habits nuon at ngayon.

note that if paglagi ka ring natatrapik or running on idle ang sasakyan pumapangit din ang fuel consumption

thanks...
the change is very noticeable! i believe this isn't just a problem on driving habits, tire pressure, etc... i had checked them anyway...probably, engine nga.