125-200cc 2011 WR150 OWNER Keeping Mikuni 38mm Carb

I'm now back to the stock needle on my CR 150. The RM needle seemed to always keep the bottom blubbery and fat. It worked great on the needle and pipe, but didn't make for crisp transitions from closed throttle to 1/4 open. Went as low as 27.5 on the pilot.

I dont really think it matters which needle you use as long as its paired upto the correct slide, you get similiar results, i tried the rm needle in mine, and was way off with the standard UK slide, just looking to ride an event now its set up correct.

Update: Did an event at weekend, and it didn't loose any fuel (from dodgy previous float height), in fact it sipped the fuel like a small 125 should, most importantly now after about 4 hours riding from knarly going to WOT fire roads inbetween sections, it never missed a beat, and was super clean and crisp from bottom to top, now i need change gearing, currently running 13/52 and gearing feels a little inbetween for woods riding, now that its running right!! gonna try 13/50 and if its very tight 12/50

I know this is an old thread.... but it's great info. I have a question.... do you guys leave the white plastic "splash" guard in the carb. The piece that sits over the mj, and pj...
My bike was bogging on steep uphill climbs. Hopefully setting the float height cures this...

yes, when i was running the Mikuni i left the white plastic piece in. Hall's modded the carb by drilling holes in the lower threaded nut.

float height is def important so get that right first.

Hi Master 62,

We are in Australia and ride at a lowly 300metres most of the time and run a stock WR 150 and a Walt modified WR 165 with both mikuni's.

The trick from what I have read with the old posts 2010ish ("lanky doug" was one that did a lot of work on the jetting) was to get pilot right first. Adjust air screw to 1 and 1/2 turns out and start bike adjust idle set screw to idle and then air screw to find highest idle from there. Shut engine and determine turns to lock on air screw, if less than 1 1/2 then too lean and increase pilot jet if more than 1 1/2 then decrease pilot. RM needle is also the go, and its pretty easy to get the half slot washers as well if you need to fine tune from there. Interestingly my 165 only needs a 15 pilot. But 150 has a 30. From there you go to main and that depends on altitude.

my five cents worth and we won't be swapping the TMXX at any time soon

Today I finally had the opportunity to test out my jetting changes.
WHAT A DIFFERENCE!
No bog. The bike ran crisp from 1/8th throttle to wot. It even lugged down in rpm's without stalling. It did take 3-4 kicks at times to get started. I'm going to mess around with the air screw some and if that doesn't do it, I'll change the pilot jet. It also seemed slightly flat on top. I'm used to a rm250 that screams to the moon. The nature of this bike is different. As it is, it's totally acceptable for offroading. Maybe down the road I will lean out the mj a smidge.
For now I'm at:
410 mj
30 pj
#4 slide
float edge parallel to bottom of carb
2004 rm125 needle in 2nd slot
Temps mid to hi 80's
elevation 1500' - 3600' asl
2009 wr250 stock bike

Exactly what Im looking for... Is there a way to repost this Images..they arent visible anymore..