2001 yz426 jetting (sea level)

I did do the search ( I promise)

Im at sea level and getting a continous poping on deceleration

pulled the bottom off the carb yesterday this is what I found.

main 162

pilot 42

f/m screw 1.75

does it hot and cold full throttle to 1/4 throttle thinking im lean

but any help would be appreciated.

stock exhaust

air box has no lid not sure if there should be one or not

getting a continous poping on deceleration

does it hot and cold full throttle to 1/4 throttle thinking im lean

These two statements disagree with each other. Are you decelerating, or are you at 1/4 to full throttle?

What I ment was at any throttle poss. when I roll of

(close the throttle) it always pops until it drops to idle.

And you read through this?:


Check the exhaust for leaks first.

Then read:




After that, go to the User Jetting DB and locate someone with a set up as close to yours as possible in terms of equipment. Correct for the altitude by changing the jet size by 1% larger for each 1000 feet lower your altitude is than theirs.

will do thanks

changed pilot jet to a 45 good to go thanks


I have a 2000. All I did when I lived in San Diego and rode the mtns and desert down there was went down one size in the pilot. Thats it. I moved up here where I ride 4500-10,000 ft and all I did was to lower the needle one clip position. I tried the 2001 needle as someone suggested that years ago, but eventually went back to the stock. Now it's pretty damn lean at sea level, but still rideable, but not lean enough to change it out for the little time I spend down there.

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