Idle & Air Screw ??

[Broken Wrist]

Yeah. I think I could take the carb off/on blind folded now. I bought every PJ from 48 to 38 and started stepping down one at a time.

I finally started seeing an improvement when I got to the 40 PJ. I had been down to 40 PJ once before, but that was with the re-build kit needle installed. Like I said previously, I don't know how much the needle would play into the airscrew and PJ settings, but it seemed to work for me.

Good Luck !!

[Chopperpilot]

I've had the same issue with the air screw not doing much (other than killing the engine fully seated). I've gone from a 45 to a 42 to a 38 PJ. It did affect how far I could turn the air screw in before the idle dropped, but turning the air screw out (even big amounts 3-4 turns!) doesn't bring the idle down after the 'high' spot. The throttle response has gotten better though! I think I may go to a 40 PJ next because I think the 38 was finally too much. It's about 60*F here and 1000' elevation. I had lowered the needle and gotten better throttle response with the 42 PJ (Went to the lowest setting from the second lowest setting). I think before the 40 PJ, I may try raising the needle back up a notch or two.

[Chopperpilot]

Yeah. I think I could take the carb off/on blind folded now. I bought every PJ from 48 to 38 and started stepping down one at a time.

I finally started seeing an improvement when I got to the 40 PJ. I had been down to 40 PJ once before, but that was with the re-build kit needle installed. Like I said previously, I don't know how much the needle would play into the airscrew and PJ settings, but it seemed to work for me.

Good Luck !!

I think the needle clip position can partially 'hide' an incorrect pilot jet, or hide a correct one as well. With a 42 PJ I was able to take the needle down to the last clip (leanest setting) and have it run better than stock jetting. When I put in a 38 PJ it immediately had an 'off idle' lean spot and sound (one of the reasons I skipped over a 40 PJ was to purposefully go 'too far'). I again went purposefully too far by raising the needle 2 positions, this created a too rich position just off idle. I went down one clip position (still with the 38 PJ, so second from the top clip) and it's pretty good. Now after seeing the difference between too rich and too lean, I'm going to put the 40 PJ in and leave the needle and I think that will be the best yet. I'm still a little concerned that the air screw doesn't seem to do much except for kill the bike when turned all the way in. I can't really tell a difference between 1.5 turns out (now with a smaller PJ) and 3 turns out. I got a jet block gasket from jets r us, I'm wondering if that is the cause? or I could also check my float height..... the bike is responding to jetting changes so I haven't actually checked the float level.
I also finally got some leaner main jets and a couple needles to play with. Question is do I try to nail the jetting and then put in the boyesen power reeds (and reset if necessary), or put in the reeds now and continue tweaking the jetting after riding the reeds to see what they do?

[KDXGarage]

Go ahead and do the reeds.

[Chopperpilot]

Installed the boyesen reeds, set the float level and replaced the jet block gasket! We'll see tomorrow how she does (when it stops raining). I left the 38 PJ in, but substituted a 150 MJ. My factory reeds were....... I dunno, first two stroke bike for me!! One had a small chip missing in a corner (that definitely let air through) and two other reeds made noise when I tapped them. I don't know how normal that is for 2 strokes to run pretty well and respond to jetting changes with reeds like that. I do think my bike isn't particularly wheelie prone (12/47 gearing), 50% of this is my discomfort with really whacking the throttle open trying to wheelie though. Odd because in my 20's I'd wheelie Harley Davidson choppers which is .....well it eventually leads to breaking the frame because 12" overlength forks, raked out, have enormous leverage!

[Broken Wrist]

I'm interested to find out how it goes for you. Thanks for the write up.

My bike seems to be running good, throttle response is crisp, no excessive smoke or oil, but the airscrew still makes very little difference to the RPM. I have talked myself into believing its at its highest RPM with the airscrew 1.5 out, but honestly if I went to 2.5 out the idle is about the same.

[Chopperpilot]

OK, finally got to test a little bit yesterday.....Noticeable difference! Hopefully there would be with chipped factory reeds going to Boyesen power reeds. Much better 'snap' and the bike is more wheelie prone now. I think it will be even more when I start playing with the airscrew for throttle response. After my trip down to my hill climb practice area I came back and played with the airscrew. I think it is changing the idle now, it just doesn't do it right away. It seems to have a 10-15sec delay when you adjust off of 'the right spot'. Oddly enough, the bike seemed a little 'quieter' too going down my road. Nothing drastic, but what I'd imaging repacking a silencer would do (I wouldn't know, because I haven't done that yet!). I think the factory needle might be a little lean (I need to paint mark my throttle) at 1/2-3/4 throttle. On the way back going up the steep paved road in 4th, I played with adding throttle and got what sounded like a lean bog and no real acceleration. The bike also didn't want to 'pick up' with steady throttle which sometimes indicates a rich condition. The bike (at roughly the same speed and slope) did accelerate when I shifted into 5th, reducing throttle to maintain speed, and then played with adding throttle. I'm pretty sure I wasn't near to tapping out on redline in 4th either.

[Chopperpilot]

So now I'm again waiting on the rain to stop. I raised the needle to the middle clip position and we'll see how that does with the mid throttle lean bog. I also bought a CEK needle and have a chinese knockoff needle that's really close measurement wise to the CEK (but a little different). A friend is sending me a DEF and a DGG needle from back when he had a KDX220. So between the clip positions and these different needles I should be able to find 'the perfect' combo. I'll be honest though, if the middle clip on the factory needle (BFQ I believe) solves the mid range lean bog..... and I find the airscrew setting for the best off idle throttle response, mmmm I'm not sure how much more experimenting I'll do.

[MoonStomper]

Geezzz… here in the western Virginia mountains the rain hasn’t let up either!!! It’s going to either depress the hell out of us or make mud riders out of us for sure.

[Chopperpilot]

Raising the needle raised the lean bog area to above 3/4 throttle (I think, I never marked my throttle). The bike definitely pulled longer in 4th gear on the uphill run, but it looks like I need to put the 155 MJ back in. The bike falls flat at full throttle. This has been really interesting and rewarding really feeling and hearing what everyone is talking about with tuning. Keep in mind, I thought my bike was running 'pretty good' before and never fouled a plug (despite being so rich). I want to encourage people to poke around jetting some, the first couple of changes you may not notice what people are talking about, but after a couple more you really notice the subtle differences.

[Chopperpilot]

155MJ back in, no testing and went and rode the Hare Scramble course from a month and a half ago (made it up the hill climbs this time!). I think I need to lower the needle back to the 4th clip spot with the 155MJ in. The bike is exhibiting slight signs of richness right off of idle that wasn't there yesterday and the idle would hang a little high for a while after coming off throttle before dropping all the way to idle. I'm going to move the needle (again) first and see how that does and maybe learn to wheelie better. After that, I'll start experimenting with the CEK needle that is supposed to be pretty good.

[Ridea200]

Chopperpilot: When you say it's falling flat, is power falling off, or does it more seem to hit a wall, and not revving out?

Edit: You posted as I was typing...From what I've seen, hanging idle means lean on the pilot. Try messing with the air screw. If that doesn't work go up one at a time on the pilot till its in range with the air screw.

Sounds like your getting there. I think at this point, act as if you just started. Pilot, main, needle.

[Chopperpilot]

Possibly, I'll keep at it of course until I think it can't get any better with the parts I have. I will say I haven't spent much time yet with getting the air screw dialed for throttle response. I have a 38PJ in and it's in the range on the air screw, in fact it seems to idle highest about 2 turns out. So I had (what I thought anyway) a great setup with the snorkel removed, 38 PJ, factory needle on #3 clip (middle) and 150 MJ. The bike pulled off idle well and wanted to fairly easily wheelie in 1st and 2nd gears (I'm not sure 'how' easily because I'm not good at wheelies yet). The only problem was WOT, on a 4th gear pull, up a steep paved road. A little above 3/4 to WOT the bike stopped pulling. The bike did this also with the needle in the #2 position (2nd clip from top) but lower on the throttle, just below 3/4 throttle to WOT. It wasn't for lack of power because an upshift to 5th gear (maintaining the same speed, so with a reduction in throttle) and the bike would pull up until somewhere above 1/2 throttle. So after that run I raised the needle to the #3 position and tried again and it moved the power falling off to above 3/4 throttle. So I feel solid about thinking the 150 MJ was too lean. Then I put in the 155 MJ and took that ride over the Hare Scramble course. The bike pulls great at WOT now but seemed to lose a little bit of throttle response in the 1/3 - 1/2 of throttle range. That's why I think lowering the needle back down to the #2 position, then tuning the airscrew for throttle response is the way forward for now.
I would assume that would tune out the slightly wallowy throttle that popped up by going to a 155 MJ, right? I'm not sure why I'd go back to swapping a pilot out now?

And of course all of this is on a top end that I know nothing about other than I just replaced the reeds with boyesen 607s (factory had a chipped corner on one). This winter I'll pull the top end and see what I have there, with such a long winter and such a short summer, no need to pull down a running bike!

[Chopperpilot]

Well something weird is happening. After getting back from my ride a few days ago and waiting on rain (again!!) I decided to put in another needle instead of moving the factory needle down to clip #2. First I tried a DGG (I got a DGG and a DEF from a friend), not because it's supposed to be great, but just 'to see'. Well the bike fire up and after it warmed up a bit it would die at idle. Messing with the idle screw had no effect. Quite a bit of smoke as well. I put in the DEF needle.... same thing. If I hold the throttle open a little the bike will run. I went to take it for a ride and discovered that the bike wouldn't rev (again, quite a bit of smoke too), it would feel (just off idle) like it was about to wheelie to the moon and then literally nothing. I brought it back to the house and tried reving it in neutral and it wouldn't rev out full throttle in neutral, just breaking up and smoking. This morning I put a new plug in, and tried again. The bike started up fine with no choke (in the sun and 60* here finally!) and in a short amount of time would die at idle just like yesterday. I started the bike again, held the throttle open a little and played with the choke/enrichner knob. Moving it in and out had zero effect on engine sound/speed/smoke. So between that and it starting without choke, makes me think the choke is always 'on'. Which I think would explain my other 'sudden' symptoms. I've looked online about the enrichner circuit and I can't find anything about failures, any ideas?

[Chopperpilot]

Well lesson learned, DGG and DEF needles won't work in a 200! I put the factory needle back in in clip position 2 and all is well! Bike is running great. I'm at snorkel removed, 607 reeds, 38 PJ, 3 turns out A/S, factory needle -2, 155 MJ. The bike pulls through WOT with the 155 MJ and doesn't burble at low throttle openings (a little still). So.......3 turns out on the airscrew is what I found when I got back to the house (with the bike hot) for highest idle. So I'm assuming that a smaller PJ is in order now and 'should' help the initial throttle opening even more? I do notice that throttle response off idle is better when the bike is warmed up, but not hot. When the bike is fully up to temperature it looses a little snap at the bottom.