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I have a built 125 and a stock 150 that are both more moto geared and have raced both in a couple off-road championships. Our trails here are 60 percent open and 40 percent tight. I’ll take the 125 (even in stock form) over the 150 any day. The benefit of the top end the 125 gives you in the open sections trumps the bottom end you get from the 150, I find myself just having to be a hair more conscious of my gear selection and clutch work in the tight stuff with the 125.

You should really adjust the power valve before you make any more changes as it will affect the jetting. I just use a flat blade screwdriver to adjust them. After getting that set if you still have a bog swap out the jetting. FGR's small bore specs. are pretty spot on.

I run the same jetting with T2.

You can go with the 5.5 slide setup if you’d like as well. I’ve run the 5.75 slide in the upper 30’s and needed to move the clip on the needle one position and put one side bigger pilot in it.

Not sure if you need to keep your bike stock. But when my son had a yz65, I put in a V-Force 4 (I think) reed valve in, and it helped that bike a ton. Also adjusted the jetting accordingly.

You can waste your time with that like many other have or you can get the slide and fix the problem. That’s the key to all of this. It’s a night and day difference over the JD kit.

Went back to stock silencer to get the turbinecore out of the equation. I will try the other needle or use a shim and see what happens. This thing must be really picky, like a woman.

You could just run T2 and not mess with mixing. The extra oil in it makes up for the oxygen content instead of having to richen the jetting up.