All 2st Jetting Chat - Need Help? Post Your Questions Here

Tank for The info!
I nave got a tmx, for wr 250, yet....but i Don't Found an corret setting.
I have also a New poi 38, but this carb Don't fit, the carburetor is too long and impacts against the shock absorber...
Can i have a photo of your pwk 38 how fit in wr 360?

I have wrote 'poi' but i meant pwk.........sorry

The PWK is quite a bit longer than a TMX and yes it does push the air boot back into the shock.

Got a TM38 from a wr360 for my wr125. Not got it running yet as i have no exhaust. What jetting should i be looking at just to get it running?

My 360 is in bits at the moment whilst l'm transferring the motor over to a 250 frame but l will post pic's when it's completed.

Check the google doc's link in this sticky http://www.cafehusky.com/threads/new-and-improved-2-stroke-jetting-database.27395/
great place to start testing your jetting against what's reported.

As far as TM settings, maybe some of the other members can guide you as l can't remember if jets and needles are interchangeable between the two but float height is critical on Mikuni's.

Is that the same as a TMX? If so, my 1999 WR125 is running 400 main and a 35 pilot stock. I just dropped to a 30 pilot to try out. Plug is dark with the 35, runs good, dead off the very bottom but comes on hard with a tap of clutch and runs out well. With the 30 it idles super smooth and I think the power starts a few hundred RPM sooner, got to get it to the track to really get a feel for it.

PC pipe/silencer.

Hello folks,
I am wondering if anyone can offer me some advise on getting a new to me 2001 CR (WB165) sorted as far as jetting...
First off, I am running around 2-3k ft and I am running premium ethanol free with 32:1 Amsoil. The bike has a 38mm PWK and doma pipe with PJ silencer, and I am told by Walt that this particular top end is on the higher compression side. The bike came with 45pj, NOZI needle in 4th position and 185mj. I think the pj is happy at 45, airscrew is out 1 turn and it idles fine. The only problem is that it only wants to start with the perfect blip of throttle once it is hot - and it sometimes takes a good 10 kicks or so (with the high compression, it is not an easy kick and doesn't like to bump start.) I always thought that if a bike wanted throttle at hot start, it was slightly rich???
Anyway, I tried a 42 jet and that was just a bit lean with the airscrew out 1/2 turn. The rps were hunting around when it got warm at idle.
On the mid range, I feel like the bike stumbles a little around 1/4 throttle, then pulls nice and strong up to 3/4. I have the clip all the down on the NOZI and think that it if it was tapered a bit lower it would work better. Any suggestions on needle?
On the top end, WOT seems flat to me. I put in a new plug and did a chop test (my first time ever, I think I did it right) The porcelain was still perfectly white and the electrode had a whitish deposit. I'm going with it is pretty lean on top.
The next jet size is 188...think that is enough? Also, will that also effect my midrange, or do I need to step that up too?
Thanks for your time, Thanks a bunch for your help!

I ran a NOZ H or a G slide was a 7 and the main was well rich around the 190 - 200 mark
Dont try starting it when warm at idle give it throttle, most smokers are a pain to start without throttle, mine even with the Lectron needs throttle to start when warm/hot

Hoping you guys could help me diagnose a slight jetting issue I'm having.

Bike: 2012 WR300, stock motor, FMF pipe, stock silencer.
Conditions: Sea level to ~2000 feet, 70-90 deg F

Carb: 38mm Keihin PWK AS (JD kit). 410 main, JD red needle on clip 2, stock JD pilot (45?), AS ~2 turns out

The problem I am having is a slight "burble" at light throttle cruise situations. It's most obvious when you're on a road connector between trails, in high gear at very light throttle (like going 40 mph in 5th at about 1/8 throttle or less). It's hard to describe but the bike "burbles" and sort of sounds like it's running under water. As soon as I open up the throttle beyond 1/4 or so, it runs fine. On the trail I don't notice it as much because you don't spend any time down there, but I am sure that it's slowing down my throttle response when I'm trying to blip the front end up on slow technical trails.

Do you guys think this is a problem of being too rich? Should I adjust it with the pilot or the needle? I went from 1.5 to 2 turns on the air screw and it might have made it a bit better but it didn't seem to have a huge impact. Bike idles fine, starts fine cold, starts fine hot (although it starts easier hot if I crack the throttle when kicking it).

Thanks!

I think you are right that it is rich and you need to go smaller on the pilot.

Thanks Doug. So, you think it is pilot and not needle, then?

I can try dropping the pilot one size, and seeing if that helps. That's easy enough!

I would start with the pilot. The needle might be rich too but only do one thing at a time. I prefer to start with the pilot then set the needle and last do the main.

Fair point, will do.

Do you have any suggestions on how I will know if going down a size on the pilot makes me too lean? I know the "adjust airscrew for high idle" trick, but I'm not sold on that being the best indicator. What else should I look for?

I think a smaller pilot will clean it up too. If you are too lean on the pilot you will usually get a hanging or slow to return idle.
I had a burble like you describe on my 250 with a 45. I went to a 42, which helped and ended up with a 40.

If the pilot is lean it will hang idle and you will have to practically close off the air screw (below 1 turn), it can also hesitate when you snap throttle from an idle. When my pilot was one step too lean it was really hard to re-start when warmed up and always took 3-4 kicks.

Thanks guys. I swapped a 42 in last night (didn't have a 40), and turned the air screw to about 1.5 turns out. Bike fired up and ran fine, still seems to have the burble, although it may be better. I will ride it more this weekend and try adjusting it with the air screw, I should have more room to play now.

Thanks for the help!

When you get the correct sized pilot you will be able to adjust the idle screw down and lower the slide a bit and still have a strong idle. When the pilot is too rich and you raise the slide to get more air you are getting the needle circuit involved before it should be. (just something to think about while you're figuring things out)

PWK38 idle circuit problems on WR144. Guys, I'm pulling my hair out here. My idle circuit does not seem to be working, or at least not 100%. The bike recently started loading up a lot at low rpms, spooging and smoking more than normal as well as consuming more fuel. I got the bike this past winter, and it has always needed the idle screw turned quite far in so it can idle, at least compared to my 165 with the same carb. I keep leaning out the pilot jet thinking that I must be rich (and getting richer with the warmer weather) but I'm now at a 38pj (from a 42) at sea level and the bike still wont idle without raising the slide quite high. I have sprayed a lot of carb cleaner through the carb, but no effect. I have also tried a 45 pj just for kicks and that doesn't help either, in fact I can't tell the difference. The bike has a JD red needle at the top clip and runs like a banshee once past the idle circuit. Please, let me hear your ideas.

Float might be getting heavy or needle might be getting worn. A leaking needle and seat will have you chasing your tail on jetting.