Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

[985johnm]

My clymer Manual is difficult to use! The basic carb adjustments are just a rpm value. Idle = 700-800 rpm ; trolling = 600-700 rpm; and WOT = 4500-5500 rpm. It also gives a timing degree for 115hp = 25 degrees +/- 1 degree BTDC at wide open throttle and 130hp = 23 degrees at WOT +/- 1 BTDC. Idle timing 5 degrees and pickup timing 4 degrees. I was looking for something completely unrelated when I stumbled on the carb presets. It says turn idle mixture screw clockwise until lightly seated. then back out 1 7/8 - 2 3/8 turns. start engine warm up and put in forward gear. then it confused me it says ADJUST IDLE MIXTURE SCREW COUNTERCLOCKWISE 1/8 TURN UNTIL ENGINE STARTS TO LOAD THEN BACK OFF 1/16 UNTIL ENGINE FIRES EVENLY AND RPMS INCREASE? Shouldn't you turn clockwise from the begining? I'm posting this for all v4 owners to get the best carb adjustment information compiled into one fluid paper.

 

[mobilemike]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

The idle timing should be 5 degrees atdc (-5). pick up timing 4 degrees atdc(-4). mixture setting '99-'03 (115) 1- 1 1/2 turns out. '97-'03 (130) 5/8- 1 1/8 turns out. These specs are from a '97-'03 seloc manual. I always start at 1 1/2 and tweak from there by turning the screw in 1/2 turn.If you get a lean "sneeze" or drop in rpm,go back to 1 1/2 and then 1/2 more out.The reason i use the 1/2 turn at a time method is that it lets me know quickly if i'm going the right way. Once i get the best idle this way, I go 1/4 turn at the time to fine tune.

 

[985johnm]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

I'll have to try this. I only have 2 carbs for my V4 115. I'll bet the V6 115 has 3 carbs. Thats probably why my initial idle screw settings are higher than the late 90's motors.

 

[985johnm]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

I backed out the screws to 2 times; and one by one I'd screw them in 1/8 at a time. I couldn't notice any change in engine idle or sound. ANY BODY KNOW What I'm doing wrong?

 

[Inducted]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

It seems like your adjusting your idle air mixture screw. If you are then set them at 1 1/2 and then leave them alone. You should have an IDLE SCREW also, adjust this screw for + - rpms.

 

[99yam40]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

it says ADJUST IDLE MIXTURE SCREW COUNTERCLOCKWISE 1/8 TURN UNTIL ENGINE STARTS TO LOAD THEN BACK OFF 1/16 UNTIL ENGINE FIRES EVENLY AND RPMS INCREASE? Shouldn't you turn clockwise from the begining? I'm posting this for all v4 owners to get the best carb adjustment information compiled into one fluid paper.

The way they are talking will leave the motor a little rich,
the way you are talking about would leave it a little lean.
I prefer to leave them a little rich

 

[985johnm]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

so 1.5 is the key if I hear ya'll right?

 

[Inducted]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

My yamaha manual says for a 1995 115 Pilot screw turns out 5/8 + - 1/4
1995 130 pilot screw turns out 7/8 + - 1/4

That means approx. one turn out. If you want to adjust your idle use your idle adjust screw. Sorry for any confusion on my part.:redface:

 

[985johnm]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

Air idle mixture screw. After reading a few posts about AIR IDLE ADJUSTMENT SCREWS I'm more confused than ever. Everyone even the experts here contradict one another.
I'm looking for fact. 1. Does the air idle screw (aka: rich/lean at an idle, highest screw on the two carbs) just meter gas going in at an idle? As I now understand it it only controls amount of fuel going into engine at an idle, does nothing to meter air. To turn it in would lean the engine and to turn it out makes it rich, at an idle.

 

[99yam40]

Re: Question: 115 / 130 V4 yamaha 2 stroke carburator adjustments

from what I under stand there are pilot fuel jets and pilot air jets in the carbs.
the pilot adjustment screw adjusts the amount of the mix into the motor.
When you turn it out it allows more and when you turn it in it allows less.

 

[brodmann]

You are 100% correct. It's not at all a fuel/air mixture screw. The air and fuel are metered by jets. Those "PILOT SCREWS" only adjust the volume of the fuel/air mixture that is used at idle and up to about 1/4 of the full throttle position. Screw out for more fuel, and in for less fuel.

 

[boscoe99]

You are 100% correct. It's not at all a fuel/air mixture screw. The air and fuel are metered by jets. Those "PILOT SCREWS" only adjust the volume of the fuel/air mixture that is used at idle and up to about 1/4 of the full throttle position. Screw out for more fuel, and in for less fuel.

Not sure I am following you.

If turning the screw outward provides more fuel while turning the screw inward provides less fuel, that equates to it being a fuel/air mixture screw. It varies the fuel/air mixture. But yes, the adjustment is made to achieve best idle characteristics. Fuel/air idle mixture screw.

The term "pilot screw" is not used by all carburetor makers. Some simply call it an idle mixture screw. Too bad we can not agree upon common terminology. Confuses unknowing folks.

Some authoritative documents suggest that the idle mixture settings will affect the fuel/air mixture well into cruise power settings.