125-200cc 09 125 WR/CR jetting thread

Yeah when the temps are warmer they seem to be,but in the cooler temps some massaging is neccessary back here in the east.
A little tweak makes a big difference though.Just setting the idle and air screw made a noticable difference.

I think it may matter how you ride. If you keep it pinned all day long and use the clutch as a throttle then the jetting is probably not very picky. I have a PWK on mine but the jetting from 5/8 on up is not picky at all. It is very hard to ever detect which main jet is the best. Below that range it is very sensitive to needle changes though.

I have installed my new parts.....we ran yesterday until dark...and I'll tell you it was like steaming hot jungle out there... swampy conditions etc..after 85 mm of rain and temps almost 90F... I also managed to snuff the bike out in a deep water hole....in the middle of nowhere......but it started after 5 kicks or so...I thought It was a goner...

BUT.....jetting was way off .....and I was quite surprised....I had to turn my airscrew out 3 turns or more( smaller pilot needed) ...I will try a 30 or maybe 27.5..I had a 40 in it

after the previous jetting I arrived(before update) at was spot on.....

Curious what every one else had arrived at with the new set up......and I think I might put the original 13T back on as well....as there is plenty of midrange pull...to handle it

I guess I'm back to the drawing board....

5.0 instead of 4.0 slide from the Factory Power up kit...... Then your jetting makes more sense, as that big a main jet (470) with a spark arrestor silencer, if you had a 4.0 slide would be really rich.

Yes for sure.....I was going to ask about the slide number...thought it may be a typo...

good info....I'm trying the needle in the middle....30 pilot...swap 470 to 460 for tomorrow

I had the rough burble till quarter throttle..then a lean hesitation around half throttle....but overall one could tell by the zingy feeling that something had changed in there in a good way :devil:


I'll save the slide trick till later when I get a sparky....

thanks kelly and norm

I had the same experience with the 32.5 on our CR 125. The 35 was too much... gurgled off-idle. The 30 was too little... lean surges and finicky idle. The 32.5 is the ticket!

How do you get to the bottom on the carb to change jets? does not seem to flip with just loosening the clamps. Also is the idle jet changeable from the bottom plug or do i have to pull the bowl off?

Loosen both clamps and slide them back well out of the way.....then pull the carb towards the rear.....and with a twist and turn pull the front out first towards you on the left side.....and voila !!!

the idea being that the airbox boot is more pliable than the stiff short boot on the reed cage....



just undo the screws and the bowl comes off...you can leave the hoses and cable attached to the card if your careful not to kink them as you work.....

I guess all your posts with the CR jetting apply now..as we all have basically the same spec now....

thanks

Not sure if its the temperature/humidity up here(90-95F) or what....but after having the carb apart a few times.....and trying some different set ups..this is the most finicky bike I have ever jetted.....I have never juggled as much brass as much as I did yesterday....

0ut came the 35.....off idle was perfect with...a 30 pilot....and a solid smooth idle...screw at 1.75 turns

needle in the middle is best...but moved it around and it got worse..... still has the flat spot.???....not bad if the throttle is twisted once....but on and off the throttle a few times and I almost went over the bars as I braced myself for the hit....that never came....


but switching to a smaller mainjet 450....made it all perfect....perfect predictable throttle response.....I'm good to go now

I will have my TC2 FMF tomorrow.....and I will try it straight up first.....fingers crossed

That sounds like hot weather effects to me Troy. Leaner in most places. Our CR's "hot weather threshold" seems to be 90+ degrees F as well. It was about 92 degrees today and I used a 450 main and put the clip in the middle for the race and everything seemed fine. I left the 32.5 in the pilot but backed the screw out another 1/2 turn from 1.5.

I must agree that these '09 125's seem a bit "picky" when it comes to jetting. Maybe the new Mikuni's aren't as forgiving as the older ones? No problem from my perspective however, since access to the carb is ridiculously easy and jetting changes take all of about 10 minutes.... THANK YOU Husky!

No kidding about the easy carb access


I think your right about the sensitivity about the new mikuni.....my 06 CR runs great at any temp....freezing to 90 above.....

funny story...in a rush and a panic....I dropped one on the screws for the top cover in the sand.... and after a few minutes of sifting sand I gave up :foul:

decided to ride with one missing .....got on the bike and away I went.....and I felt a rock in the bottom of my boot so I stopped to get the rock out....and low and behold...I found the screw

I wish *I* was that lucky with lost hardware!

That's strange, everyone always complained about the sensitivity of the old mikuni, I switched to a PWK and never looked back. Was hoping the new TMX was better. I think it comes down to the fact that they are squeezing so much out of this little motor, thus making the jetting finicky with any carb. For me the PWK is better, but I still change a clip every once in a while and almost always have to adjust the air screw. Mains I only change due to larger swings in the weather, or just to be on the safe side.

the only issue I have the the 06 CR is terrible idle quality....I just keep it high now and forget about it....which is OK for MX....

the 09 WR on the other hand....has a rock steady idle....time will tell when the weather cools off how finicky it really is...

I havent tried a PWK on a 125...but on a WR250 I tried it was really nice....