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DRZ125 Jetting for Pro Circuit T-4

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We finally have the T-4 Pro Circuit on the way. The air box has been opened.

We plan to re jet the carb. Here is what we have planned.

( Sea Level 90 F)

Main jet 105, Yamaha TTR125 "Needle Set" and turn out the Pilot jet 2 1/2 turns from fully seated.

Anything else to consider

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We finally have the T-4 Pro Circuit on the way. The air box has been opened.

We plan to re jet the carb. Here is what we have planned.

( Sea Level 90 F)

Main jet 105, Yamaha TTR125 "Needle Set" and turn out the Pilot jet 2 1/2 turns from fully seated.

Anything else to consider

I think you'll need to go a little bigger on the main, at least a 107.5, maybe a 110. A 20 pilot helps too.

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The Mikuni PDF http://www.mikuni.com/pdf/vmmanual.pdf does not match the carb we have on the DRZs. The Air screw (29)also called the pilot screw? is not on the upper right rear of the carb as shown. The pilot screw is under the brass plug inside the float bowl next to the main? Drill out the plug and turn pilot out 2 1/2 from full in.

What is the adjustment screw on the left side towards the bottom on the outside of the bowl? Idle screw? The screw on the bottom of the bowl is not shown on the PDF . 😢

Checking to make sure I get it right, Main 105, 107.5 or a 110 main. Pilot, drill out the brass plug on top of the float bowl. Turn pilot 2 1/2 from full in, go to a size 20 pilot if needed. Change to TTR needle, set in the middle clip.

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Is the pilot screw inside the float bowl and you have to drill out a brass plug to get to it?

Where is the idle screw, bottom side of float bowl?

It is hard to modify this carb without info 😢

Thanks for the help, in advance

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Go to Yamaha of Troy's website: www.yamahaoftroy.com

Click on the "OEM Parts Finder" button. Then click on the Dirt Bikes under Suzuki. Then enter your model year. Then choose the DR-Z125. Then choose the drawing for the carburetor. This is a drawing of your actual model VM carb.

Have fun...

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Replaced the needle set(TTR125), main jet(107.5) and drilled out the brass plug and turned the adjuster out 2 1/2 turns from closed. The adjuster was at 1 1/4 turns. Bike starts easier and warms up quicker. Will ride it tonight after we fix a flat front tire. Tip: when you drill out the adjuster brass plug, drill with the float bowl cover on. This eliminates chance of getting fillings into the carb 😢 Pro circuit T-4 sounds good and is not to loud, fit easy

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