Idle screw question

[getherejune]

Hi all-new member here. This is an awesome site. Have been lurking around for a few months before pulling the trigger to add an 02 kdx220 to the garage to ride with my thumper ;) So, going thru the bike with my son before we take it out anywhere. Today went thru the carb-total clean out with a keihin rebuild kit. (has the stock pwk33) Carb looked very clean and maintained. No gunk or rust. PJ 42, Main 148, 2nd clip down. My son actually bought the bike in CA and then brought it back home to WA (so he can have a bike both in CA where he lives and here in WA when he comes home to visit...and it will give me a smoker to play on occasionally as well!). So when he bought the bike he told me he didn't have to choke it at all to start it-fired up first kick when cold. Told him that the PJ was probably a size or 2 too big, and not to worry about it-probably easy fix. (A bit surprised to find it was a 42 which is what the manual has down). So using the jetting guide i found on here, we set the air screw at 1 1/2 out (it was at 2 1/2 out) and attempted to adjust the idle screw to get it idle a bit fast-no dice. Didn't matter if i went way in or way out, the idle didn't change. So just to make sure i'm thinking about it right, i should go down a size on the pilot, correct? I'm by no means an expert at jetting, but i know a tad bit after having a yz125, an orange bike, and a beta, but 2 of those had a jdj kit in them so they were pretty spot on. No reason to move on in the process unless i can get the idle screw to affect things. Son said it ran the same after the rebuild as before, so we didn't mess anything up with that process! I know ive read that these come set up way rich, and it was spooging and smoking a bit more than normal, so thinking i'm on the right track-but ive done things before that i'm not super familiar with and it has cost me a ton of time, a bit of money, and lots of frustration so figured i'd ask for a little guidance. Thanks all for any help/wisdom you can share-appreciate it!

[getherejune]

ps-yes, float height checked and at 16mm (forgot to mention that!)

[SS109]

Don't use the factory float level height. The factory setting tends to make the carb run richer than it should and makes jetting a pain. Set it to 18mm before doing anything else, adjust the air screw again, and see if it changes. Sometimes it will, sometimes it won't.

Ok, if nothing changes... 2.5 turns out on the air screw indicates a rich pilot jet. Yes, one step down to a 40 should get you closer. Remember, you're always trying to keep the air screw between 1 to 2 turns (1.25-1.75 ideally) out.

[getherejune]

thx for the reply ss-so, if i'm at 18 now, if i adjust to 16 wouldnt that give me more fuel in the bowl=possibly richer as more fuel available to get sucked in? (sorry if thats a dumb question-always trying to learn!) and yep, have the a.s. set at 1 1/2 after the clean/rebuild to start. Just concerned because the idle screw is having no effect on idle, and according to the jetting guide on here, i've got to use the i.s. to get my idle up just a bit, which i can't do.
I did take out the carb this am before work to bring the jets w/me to the shop to make sure i get the right ones-noticed the PO had the idle screw almost all the way in (actually 1/2 turn from being fully tightened) so that would mean its putting almost max fuel in there (which may explain why the PO had the a.s. almost 3 turns out?). I backed it out quite a bit so i wouldn't be at the extremes and i did change the clip back to 2nd from the top.

[SS109]

If you look at how you set the float, 18mm is actually lower than 16. Remember, when you're setting the float height the carb is almost upside down. So, higher upside down means lower when the carb is right side up! Confusing, huh? Make sure when you do check the float height that your tipping the carb just enough to close the valve when you measure it. The little spring loaded plunger on the needle should not be compressed at all when checking the height.

[getherejune]

Solved!!! -for future reference for anyone, it was the jet block gasket (should have known as i went thru the same thing with a previous 2t i had years ago). We actually did the jet block gasket test (see you tube). Basically remove the bowl and jets, turn your carby upside down, get your vent lines above the carb, and fill the bowl with gas. Then take some air and gently blow air down the pilot hole. Bubbles show a bad gasket. Ours was bubblin'. Luckily JD Jetting is right down the road and i shot them an email, and they had a jet block gasket -#JDKH46. They werent sure whether it would fit the pwk33 so they called the manuf. to confirm, and indeed it did. They got it out to my local shop in a few hours for me. When we removed ours, it was flat as a pancake. Put it in, along with a 40 pj and 145 main, and on start up i could tell it was a different bike. MUCH less smoke, no spooge splatter on the back fender, and best of all my idle screw works now Also, the bike would stall when coming to a stop with the clutch in...that is gone now too. So now on to getting the jetting dialed in. Hope this helps someone down the trail!

[bufftester]

Lots of info on here regarding jet block gasket. Most usually goes bad when someone dips the carb in Berrymans. Glad to hear you have it sorted.

[SS109]

Good deal!

[getherejune]

thx guys-yep, I know some folks go ballistic with the carb cleaner or dipping it and that stuff will eat the seals. Bufftester-did you ride in the PSER poker run this past weekend in shelton? We rode in that on sunday and saw quite a few kdx's (now that we have one i've got my eye out for them!)

[bufftester]

thx guys-yep, I know some folks go ballistic with the carb cleaner or dipping it and that stuff will eat the seals. Bufftester-did you ride in the PSER poker run this past weekend in shelton? We rode in that on sunday and saw quite a few kdx's (now that we have one i've got my eye out for them!)

Yep, Only rode on Saturday though, had family commitments Sunday. Saturday was a soaking wet mudfest out there....lots of fun.

[getherejune]

crap man-you are my hero. I live about 5 min away from the fairgrounds so the wife and i ran up there to see what was going on. Was pouring hard the whole day! i talked to the member that was more or less in charge (he's my neighbor) and he said they had over 700 riders on saturday. We only did sunday and it was great weather, but there was lots of rutty mud holes. (I only got to ride the first 8 miles as my son came home from redding CA to ride with me in it...he threw a chain on a muddy rutted small hill climb. Waited for him 15 min on the road ahead and finally got down to him. Chain was stuck between the hub and the swingarm on the front, and ran up on the countersprocket up front. When i removed the chain guard up front, discovered the chain had taken out a piece of the case that held the sprocket guard bolt. Nice hole in the case about the size of a fingernail. (i let him ride my bike and finish the long loop while i waited to catch a ride back) My son said after the 1st check point the riding was amazing

[bufftester]

Ouch on the chain issue. Our ride Saturday was marred by a crank seal on his RMX giving up. Won't be many mosquitoes in those woods this spring lol. I do most of my riding down in Capitol Forest once it dries up a bit, not far down Hwy 8 from you at Rock Candy Mtn. Should be interesting this season as they logged out that side of the forest last year.

[Curly]

I have a question regarding testing the jet block o ring. When doing this as you described I hear air coming out of a few orifices of the carburetor but it does not bubble from the O-rings up through the gas. Is hearing the air coming out of the other orifices OK while doing this test?

I have the same low idle problem so many have described with the idle screw all the way in.
-fully cleaned carb and also replaced Jet block a ring, new V force reeds, new full FMF exhaust.
When bike is idling I spray starter fluid around all potential intake leak areas and idle does not fluctuate.

7,000 elevation,
Jetting
Main =145
Pilot =35, also tried 38 and no significant difference
1 1/2 - 2 turns out on air screw is where it runs best
Red needle, 2nd clip
Float =18mm
Going to try 20mm on the float now.

[MoonStomper]

If your jbgasket was compromised you would see bubbles during the test.
16mm is actually higher (remember it’s upside down-ish when you measure it. Sounds like you have potential air leaks covered. I haven’t ridden at 7k’ but maybe another size smaller on the pilot?

[Curly]

I'm wondering if lowering the float from 18mm to 20mm could lower fuel pressure and potentially reduce an over rich condition during idle.
If that's the case that would explain the need for idle screw being in all the way allowing additional air to pass by the slide to even out the mixture.

Bike runs great, I just dont like having idle screw all the way in and just barely idling high enough, it's actually just a smidge lower than I like.

[SS109]

Yeah, you can hear air elsewhere. If no bubbles from the gasket coming up through the gas then you're good.

Sounds like your pilot jet is right on. On the float height, 18mm is already 2mm lower than the stock 16mm. Be careful or you might actually starve the bike for fuel. Also, testing with starter fluid is a good start but it won't find a case or crank seal leak. A leakdown test is the only way to know for sure.

I think your pj is spot on going by the air screw but your main seems fat to me. I would try a 142 and even a 140. Just for reference I'm at 2000ft and run a 38pj, 148 main, CEK needle, with air screw always in the 1.25-1.5 turns out.

By any chance the tip of your idle speed screw good? To adjust the rpm's higher you need to open the throttle while adjusting them or it can damage the plastic tip.

[John_S]

I would swap the carb slide from your other KDX just to see what happens. A worn out slide can create a rich idle. I had a 36 PWK that Idled real low with the screw all the way in. I installed a brand new slide (same cutaway) from another carb and when I fired it up it was idling about 3000 rpm’s. I lowered the slide and it purred at idle.

[Curly]

Thanks for confirming the air from elsewhere, I feel better about that now.
Just tried float at 19.5mm (that’s what my bad reading eyes see), didn’t make a difference.
Interesting, it did start this morning with no choke, first start of the day (hadn’t tried that before).
Hadn’t tried a 142 but will give it a go this afternoon.
Just checked the idle screw and it looks clean, the end is a nice round shape.

I did try the carb from my other bike and no difference, I did NOT try the other slide though, on that today as well.

I did pull the cover off the left side of bike to spray ether by the flywheel when running, no idle change.
If the 42 main doesn’t make a difference my next step is the leak down test.

Thanks for the suggestions, it’ll be fixed shortly I believe.

[kdxdazz]

I have a question regarding testing the jet block o ring. When doing this as you described I hear air coming out of a few orifices of the carburetor but it does not bubble from the O-rings up through the gas. Is hearing the air coming out of the other orifices OK while doing this test?

I have the same low idle problem so many have described with the idle screw all the way in.
-fully cleaned carb and also replaced Jet block a ring, new V force reeds, new full FMF exhaust.
When bike is idling I spray starter fluid around all potential intake leak areas and idle does not fluctuate.

7,000 elevation,
Jetting
Main =145
Pilot =35, also tried 38 and no significant difference
1 1/2 - 2 turns out on air screw is where it runs best
Red needle, 2nd clip
Float =18mm
Going to try 20mm on the float now.

As a test try going to the 1174 needle, JD red needle is 2.73 and stock 1174 is 2.74 , can make a big difference at idle, consider using the clear tube method when setting the float height, numbers can become irrelevant when you add up the sum of worn parts, if still too rich at idle then cut the slide to a number 6

[Curly]

I’m not sure why but idle screw is now 4 turns out and bike is running really well. How many turns out are some of your idle screws?

I did try the slide from my other 33 carb, made no difference.

Leak down test completed, no loss of psi after 5 & 10 minute test, pumped to 5.5 psi. When done testing I pulled the plug out of exhaust side of cylinder and heard the air rush out. Did the test at top dead center and also at bottom of stroke (I’ve seen different suggestions on where to have piston so did both).

60 degrees 8,400 elevation.
Main=140
Pilot=38
Red needle, 1st clip
Float 18mm
Mix and idle screws both at 2 out.
Real strong and quick throttle response in the first half of throttle. Wanting to tame this down a little and make mid to upper throttle range feel stronger.

Morning ride, 50 degrees, 8,400 elevation.
Main=140
Pilot=35
1173L needle, 1st clip
Float=18mm
Had a small bog around 1/8 throttle, not sure if it was lean or rich but I think it was rich. Idle screw is four out, mixture screw was two out. Tried second and third clip and was definitely rich and got richer.

Temperature now likely 60 degrees still at 8,400 elevation.
Now running JD red needle 2nd clip.
Idle at 4 1/2 out, mix at 1 1/2.
No more bog and runs great.
Now tried 142 main. Seat of the pants says 142 is better than 140, no room to do plug chop today.

Maybe taking these jets out so many times in the past few days has caused some piece of grit to finally break loose that I never could find.