125-200cc WR125 tuning question

'09 WR125 with Kiehin PWK, 180 main, blue needle, middle notch at the moment (don't know what my idle jet is, whatever it came with from Kelly). Idles nicely and pulls decently up to mid range where it hits a brief plateau and pulls like crazy from there. My question is if I am at a fairly low RPM and suddenly whack the throttle, it falls on it's face. All that I can think is that a 38mm is a big carb for a 125 and there simply isn't enough volume moving to keep drawing fuel. On trails, I almost never experience it since I seldom nail the gas that quickly. Is this something that I have to live with or can I tune it out of it. I have Wally's spring kit, but haven't changed anything yet. I have a hare scramble tomorrow and didn't want to mess too much. This is my first two stroke so I'm having a bit to learn.

I had the same issue with the blue needle in my 144 and raised the needle/lowered the clip one spot and it cleared up the whack it bog. We are worlds apart in altitude and climate but it might be worth a try.

Walt

180 is a bit leaning on the big too. try the needle first then maybe a 178 or 175 main

I had the same issue -thought it was a lean bog
it only happens now and then and it really is just blah and nothings there
went richer on the pilot and bike felt dead - rich
went leaner and rode all day today with not one bog!!

I don't think that I have any other pilot jets. Maybe I need to order some.

Try your local Husky dealer - mine had some secondhand ones at $10 a pop

yikes I paid $5 for new ones at my dealer ...

I have had that very problem with both the mikuni and kehin, and I first thought it to be a pilot problem. Aftermuch testing, I realized that I could whack it open from idle to half no problem, which says pilot is good. It was going lean in the midrange, blue needle did not work for me.
I wound up with 40 pilot, 185 main and NOZF needle in the 4th slot, I also have PV spring kit, silver and blue I think, and it now is working pretty well. May need a bigger main, but did not have one to try. My bike seems to like a lot of fuel right in the middle.
I have the mikuni working pretty good as well.
GP

never been a fan of JD needles.......too generic......Keihin numering system for needles is sooo simple to find what ails you and same system.......OK...gonna shut up now

I rode David's (Scootskippers) bike the bog or die happens right as you open the throttle. If you just wack it open nothing happens it's a long pause then it slowely starts to go. Kinda scary comming up to jumps on the MX track. Once past this or if you give it the gas very slowly she pulls very good. I know he had the blue needle in it. Do you feel he should be running the red or another needle all together? At first with a 185 in it and on the 5th clip the bike wouldn't pull at all in the mid range. With the 180 and 3rd clip it way better but not perfect I don't think. It's hard to tell with the big stall at fast throttle openings. Any other suggestions?

Here is the test I did. Go slowly in second gear, whack it open to maybe half. If it pulls, then maybe the pilot is ok. If it dies, then go bigger pilot, or raise the needle. if it does pull, do the same test but whack it open full, if it dies, go bigger main or richer needle, for me that was a NOZF. It is a 125, so there will be some bog doing this test. I am not a jetting expert, but this is how I have gotten my bike to run. I think with more testing I will get it better.
I am sure that some that have good running bikes at leaner settings think that I am wrong, but not all these bikes are the same, and we do have different climate and elevation, and gas availability. After all, I got my bike at a good deal because the previous owner could not get it to run, and he is a 6time ISDE racer!
GP

Thanks for your suggestions GP. David's bike just won't go if you wack the throttle while in first or second on a slow roll. It has to build RPM's then she rips. I think its in the pilot and I am not sure which one is in his bike....David which is it?

I don't know what pilot it is. I'll ask Kelly. Are you around Saturday?

Got my carb from Kelly a couple months ago and it had a 45 pilot in it. Mine had a bog (sometimes) that I "think" I finally tuned out. I'm running a 165 main, red needle 3rd pos, and a 42 pilot, AS 2 turns out. I haven't trail tested it yet, just running it up in down the gravel road here. I'm running lean cause I do mostly trail riding in the lower rpm ranges. Elevation: 700 ft, 80 degrees, 93 octane w/ Amsoil at 40:1. Will let ya know how it does on the trails after this weekend.

I think so David if not at my place the club. I should know something later in the week. Thanks Philbilly. I think Davids pilot is the problem but he is running the blue needle. David I will check and see what pilots we have in our inventory. Did you race Sunday?

Do we really have to talk about that?

I'm eager to hear how yours is doing. I have some other pilot jets that came with the bike. I don't know if they fit the PWK or not. Thanx for sharing.

First Off, the PWK has a 45 Pilot in it. I went 42 then 40. It was getting too much fuel when you rolled the throttle. I was going to even try a 38 or lower but pulled my back out. I went with the 185 main and I think that I am going to push to see if a 190 will work. My bike likes fuel on top and lean on bottom.

Water racer where did you get your NOZF needle at?

Thanx!

Yes David it's better to talk about things...so lets hear it.