ski
New member
Simple question .... from a simple guy. Which way do you turn the fuel screws to lean out the sled? In or out? I am assuming in will lean it out, but when you assume ... well you know...
ski
New member
Thanks Turk, you are both a gentleman and a tuner .... merry X-mas.
snowhite
Member
Hey Turk;just been browsing and I noticed your answer to ski's question was to turn the (fuel) idle mix screws in for a leaner mix! Now as I understand it's not the fuel you are controlling here but the air that's coming in thruogh the pilot system(air jet) in the throat of the carb.The screws(pilot)allow air to enter and then the jet allows gas to be mixed with it.now to turn the screws in would make the mix richer as your eliminating air and giving it more GAS!! If i'm not mistaken that's how this system work's,if anybody else can help let us know.thank's, KAPUSTA>>>>>>>>>
daman
New member
Holy old post batman...
in is lean,, out is rich,, when adjusting the low speed circuit (fuel screw,pilot screw)
in is lean,, out is rich,, when adjusting the low speed circuit (fuel screw,pilot screw)
IN is lean. They are fuel screws, not air screws.
Just remember guys that there are carbs with fuel screws and then there are carbs with air screws. Make sure which type you are referring to . . .
daman
New member
Right..i guess the OP did not specify what sled he was talking about...
I think he has them mixed up with round slides with air screws.There the opposite.
snowhite
Member
O.K. guys';here we go if you look in a service manual at carb function you will notice that there are usually 4 pictures indicateing carb. function.Now under the topic of part throttle the pictures show the circuits used.Now if you notice that typically the pilot system circuit allows air to enter passing by the air screw(idle fuel mix)then picking up fuel from the pilot jet circuit and entering the throttle bore.Now if the air entering this circuit is increased(screw out)it dilutes the fuel(more air)thus leaning the mix;also if the screw is turned in allowing less air(more fuel)thus richening the mix !Where does it indicate that a snowmobile carb.(TM31)that the idle circuit allows gas first then air??? Auto. carbs work this way ,unless Yamaha has a different system.Location of screw
If you do a search of MRVIPER700's posts you will find an explanation of the difference in how air screws and fuel screws work and where they are located on the carb iteslf. From memory I think it was like this:
Air screws: located before the slide (toward air box) - out is leaner
Fuel screws: located after the slide (toward motor) - out is richer
Good luck!
Madmatt
If you do a search of MRVIPER700's posts you will find an explanation of the difference in how air screws and fuel screws work and where they are located on the carb iteslf. From memory I think it was like this:
Air screws: located before the slide (toward air box) - out is leaner
Fuel screws: located after the slide (toward motor) - out is richer
Good luck!
Madmatt
Kapusta, that would be right if you had a carb with air screws, but the modern Yamaha 2 stroke carbs have fuel screws so it's just the opposite.
snowhite
Member
Alway's learning something new.
Than's guys'. Got it figured out now,but it's always interesting to find out something new everyday.......KAPUSTA....
Than's guys'. Got it figured out now,but it's always interesting to find out something new everyday.......KAPUSTA....