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Fuel Screw Frequency of adjustment

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How often do you have to adjust your Pilot circuit Fuel mixture Screw (FS) to suit changing temperature and altitude ?

I'm directing this question mainly to people running after market high flow exhausts and Flat slide carbs as I assume the stock setup requires little adjustment

I'm running a 2003 DRZ400S with FMF Powercore exhaust and Yosh-Mikuni TMR MJN flatslide carb with pumper, pilot jet 27.5, FS 2.5 turns out

Bike runs good through all carburation ranges at sea level and warm dry weather.

As soon as it rains (and the resulting drop in temperature), it backfires loudly on decel indicating a lean pilot circuit

At 2.5 turns out , the FS is already at the end of its range.

Thinking of going next size up on pilot jet to richen the range of my FS adjustment, possibly running 1 turn out on FS for warm dry conditions with plenty of range left for cool/wet conditions.

Also thinking of trying to source an extended fuel screw for my carb to make frequent adjustment less painful

Do other people running high flow exhausts and/or flat slide carbs find that frequent adjustment for changing conditions is required ?

Interested to hear others experiences.

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I don't adjust mine often but I can't say my jetting is spot on either. If you do get an extended fuel screw get a brass one they seem to be more consistent[bought a aluminum one never did work :thumbsup: ]

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I am posting on this because I found it while searching and have the same question in regards to adjusting the screw for temp changes. I do not have an aftermarket carb. Please dont tell me I dont need to worry about it if I only have the stock carb. I just want to know. Thanks guys

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On my DRZ, twice a year, summer and winter. Summer when it is 90F, winter wehn it is 40F. Typical is about 1/2 turn.

On my WR, I set it every time the temp swings more than 10~20 degrees. It is more finicky.

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I tweak mine when temp changes, way more often than on my XR's I had.

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As I live in the tropics and at sea level where there isnt much chance of getting to ride any higher than 1000 feet , I havent touched mine since I put it in 3 years ago :smirk: , greg

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Twice a year once in the spring/summer transition and once in the summer/fall transition. Half turn maybe.

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