I’ve been modifying my 150 for a while now trying to get the power just right and I am happy to say “mission accomplished”. The power is just amazing now! It pulls so much harder than it did as a stock WR150. The throttle response is instant and it will get singing on demand with no clutch work. It will still chug when needed but the mid is so broad and easy to stay in that I usually just keep it in the meat of the power. It might be a bit too quick and strong for a beginner but I am loving it and it is just so much more fun to ride now. I let a guy from TT on a CRF450 ride it and in a mile all he had to say was “I’m buying one”. Anyway, I know others are tuning the same bike so I want to list what I have done in case anyone finds it useful.
09 WR 125 with factory 150 kit.
CR ignition advanced 1-2 degrees.
Stock carb with RB Designs divider plate, air screw, and low speed mods. Jetting was perfect in the morning (37 degrees) with 30 pilot, chy16-61 needle at 3.5(I had a half clip spacer in it), 460 main, #5 slide. It still worked well at 65 degrees in the afternoon so I know the carb will not be too picky. I took out the half clip needle spacer though and gave the air screw a turn and it was perfect again.
Head squish set at .9mm by RB Designs
Walts power valves which I set as close to the piston as I dared.
FMF Fatty with TC2 silencer
Straight AV-Gas with Lucus premix at 32:1
09 WR 125 with factory 150 kit.
CR ignition advanced 1-2 degrees.
Stock carb with RB Designs divider plate, air screw, and low speed mods. Jetting was perfect in the morning (37 degrees) with 30 pilot, chy16-61 needle at 3.5(I had a half clip spacer in it), 460 main, #5 slide. It still worked well at 65 degrees in the afternoon so I know the carb will not be too picky. I took out the half clip needle spacer though and gave the air screw a turn and it was perfect again.
Head squish set at .9mm by RB Designs
Walts power valves which I set as close to the piston as I dared.
FMF Fatty with TC2 silencer
Straight AV-Gas with Lucus premix at 32:1