Analyze this spark plug

[Speedgoat]

Just finishing my build on a 200s. Trying to improve the throttle response. Right now has stock carb and stock plug. Put this brand new plug in, ran it wide open for about 1000yds. This is what it looks like. A good friend, who know a lot more than me about engines, told me it looks lean.
What are your thoughts and what adjustments could I make.
(It starts first pull, idles fine, throttle response is very slightly delayed when taking off from stop, pickup and response is a little slow in higher gears. Top speed 43.0)

[rocks]

You are running super lean. Not good.
Adjust the air screw. Try to close it all the way down then test. I am not sure how many turns out it needs to be, but give it a try. Better run rich than lean.

[Speedgoat]

Do I mess with the needle at all or just start with air screw?

[yaegerb]

Way to lean.

Are you running OEM airbox with OEM filter?

What model carb? PD62B?

[TwiZ]

Do I mess with the needle at all or just start with air screw?

Air screw,front of carb engine side..Gently seat it if you screw all the way in. I usually go 2 turns out and go from there,i think book says turn n a half. Wanna try and get it where its in between dying when screwing in and same screwing out,wanna get it where it idles the higest between these two positions,if that makes sense

[RubberSalt]

Based on that. It looks lean. If you ran WOT for 1000 yards, and that's the results, your main jet may be to small.

Try pulling the choke and see if it gets any better. Partial choke/full choke. This will richen it up and give you an idea.

The only way to get a "true" reading is to cut the threads on the plug off and look at the insulator between the threads and the porcelain. This part changes color first.

[AK47KID]

Omg I 'bout fell over!! Lean very lean! Do what twiZ said

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[RubberSalt]

AK47kid, the fuel screw adjust the low end circuits of the carb. He's running WOT and seeing that. WOT is determined by the main jet. At WOT, the pilot circuit on contributes about 2% of the fuel. The main jet does the rest.

Air screws are on 2 stroke carbs. They adjust the air going into the circuit. These are near the Air filter side of the carb.
Fuel screws are on 4 stroke carbs. They adjust the fuel going out of the circuit. This is on the engine side of the carb.

[TwiZ]

AK47kid, the fuel screw adjust the low end circuits of the carb. He's running WOT and seeing that. WOT is determined by the main jet. At WOT, the pilot circuit on contributes about 2% of the fuel. The main jet does the rest.

Air screws are on 2 stroke carbs. They adjust the air going into the circuit. These are near the Air filter side of the carb.
Fuel screws are on 4 stroke carbs. They adjust the fuel going out of the circuit. This is on the engine side of the carb.

You are absolutly correct,and i was sloppy by calling it a air screw,and i was using it as a generic term and should have called it a fuel screw,my bad. I was explaining this to him due to the slight delay and off line response.When i tune a carb i start with setting fuel/air mix,thats just me. Ive been doin this stuff for years just dont explain well sometimes. Thank you for catching that.
Check and see where the clip for the needle is,should be in the middle,drop your clip down and it should richen it. If not enough try the last notch. If its better id get a little bit bigger jet. If i remember right it has a 108 in it,38 or 40 pilot

[Speedgoat]

Way to lean.

Are you running OEM airbox with OEM filter?

What model carb? PD62B?

OEM airbox with a moose faom filter over the OEM metal screen tube

carb is PD85C, main jet is 100

[Speedgoat]

Air screw,front of carb engine side..Gently seat it if you screw all the way in. I usually go 2 turns out and go from there,i think book says turn n a half. Wanna try and get it where its in between dying when screwing in and same screwing out,wanna get it where it idles the higest between these two positions,if that makes sense

yes that makes sense. that is exactly what i did initially to get the results in the pictures

[Speedgoat]

AK47kid, the fuel screw adjust the low end circuits of the carb. He's running WOT and seeing that. WOT is determined by the main jet. At WOT, the pilot circuit on contributes about 2% of the fuel. The main jet does the rest.

Air screws are on 2 stroke carbs. They adjust the air going into the circuit. These are near the Air filter side of the carb.
Fuel screws are on 4 stroke carbs. They adjust the fuel going out of the circuit. This is on the engine side of the carb.

my understanding is the needle only affects about 1/4 throttle to 3/4 throttle. at WOT, the main jet is the only factor.Is this accurate?
if my main jet is not clean, could it cause it to run lean?
Will adjusting the air/fuel screw change anything if I am only doing plug checks at WOT?

[yaegerb]

I would change the main to a 108, leave your pilot alone for now and drop the clip one groove on the needle. Also leave your pilot screw setting where you have it.

[Speedgoat]

I would change the main to a 108, leave your pilot alone for now and drop the clip one groove on the needle. Also leave your pilot screw setting where you have it.

any recommendations on where to get new jets without dropping a lot of cash?

[yaegerb]

any recommendations on where to get new jets without dropping a lot of cash?

Jetsrus. But get the genuine jets, don't get the OEM equivalent.