just another jetting question

Discussion specific to the 1995 - 2006 KDX200 (H Series) and 1995 - 2005 KDX220R (A Series) models sold in the USA
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737diesel
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just another jetting question

Post by 737diesel »

Hey guys, I am 2/3 through the jetting guide and ready for plug chops. Here is my situation: 2004 KDX200 with a fresh top end(break-in complete), new Boyessen super stock reeds, new FMF Woods pipe and Turbinecore 2 muffler, No toil air filter, snorkel removed. Before the top end and all the new stuff, I had a 45 pilot, 160 main, needle clip second from the top. Now Ive done the steps to get the pilot jet tuned and clip position set, I am at a 40pilot and clip in the top notch of the needle. I will have to take the bike somewhere besides my neighborhood to do the plug chop runs, but before I do are my setting so far in the normal range? I know every bike is different. By the way, Im at sea level running ethanol free gas with Lucas semi-synthetic at 40:1, air screw is at 2.5 turns out, and standard BR8ES plug.
Would anyone venture a guess as to where my main jet may end up?
Thanks!
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Re: just another jetting question

Post by SS109 »

If you followed the jetting guide you should be good. However, at 2.5 turns out is further out than I'm comfortable with. I would be stepping down to a 38 PJ as I like the air screw to always end up somewhere between 1 and 2 full turns out. Setting it that way allows you plenty of room to adjust if it is cool in the morning yet gets hot later in the day and/or if your elevation changes a bit. It also has less chance of somehow vibrating out and getting lost somewhere on the trail. I know it's not likely but I'm paranoid over such things.

If your needle clip works best in position 1 (top - leanest) then you need to step down a main jet size before any more tuning can be done. Why? Because the the needle might run better if it could be lowered even more indicating the main is way too rich. If currently at a 160 I would drop to a 158 and start your needle testing all over again. Start in clip position 3 (middle) after the main swap and adjust from there. If you end up in position 1 again I would drop the main to a 155 and start testing the needle again. You want to try to end up somewhere in the three middle clip positions on the needle if possible but it doesn't always happen. I would bet you end up with a 158 or 155 main jet.

BTW, what needle are you using? If a stock Kawasaki needle I suggest trying a CEK needle instead as it is a proven performer in the KDX.
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737diesel
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Re: just another jetting question

Post by 737diesel »

Thank you SS109, the detail in your response was just as valuable and more specific than the guide itself. I found that CEK needle on jetsrus and ordered it, as I am still using the stock one.
The knowledge available on this site regarding KDX's is incredible. I search craigslist(Portland OR) every morning, and KDX's do not last long! Owners of the KDX have a helluva database at their fingertips. Every question Ive asked has always been answered.
Thanks!
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Re: just another jetting question

Post by KDXGarage »

May I ask what the total was for the needle, with shipping? I have a friend on here, treelimb, that should get one.
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Re: just another jetting question

Post by 737diesel »

Sure, the needle was $12.99, then jetsrus sticks you with $7.99 shipping.
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Re: just another jetting question

Post by KDXGarage »

Ouch. Thanks for letting me (him) know.
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Re: just another jetting question

Post by bikeman2502001 »

Well jetting always depends where you live here at sea level hot and really humid and in the woods not wide open territory Ive ended up with 38 pilot every two stroke with a pwk ive owned no matter what brand bike and regardless of CC it is i ended up with a 38 for a good idle quality but not for really fast areas Stock needle in the 2nd position and a 155 main. runs pretty good around here Air screw 1 1/2 out and for those who ever wondered I tried the 7 slide dont waste your money unless you live a top mount Everest It was a huge BOG Dog off the bottom rode for 5 minutes went home
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Re: just another jetting question

Post by KDXGarage »

THANK YOU!!! for the 7 slide report!

Another great tip from you. Thanks!
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Re: just another jetting question

Post by 737diesel »

More frustration! I replaced the stock needle with the CEK that SS109 recommended, with the clip in the 3rd groove. Pilot at 38, Main at 155, screw 1.5 turns to start, needle now in the "2" groove, fresh plug every time i change the jetting. At those settings, Im having trouble getting a clean idle to first 1/4. Could I be too lean now? If you read back through my posts you'll see where I started, and where Im at now. Ive got spooge all over my swingarm ('Ive read the fix for sealing that pipe/muffler joint better), which makes me think I'm still way rich.
BTW, all my reductions in jet settings have been one at a time. I had an easier time tuning the pilot when it was at 40-42, but my needle was in the top groove and the screw was more than 2.5 turns out. Should I maybe try the pilot back at 40-42 with the new needle I put in?
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Re: just another jetting question

Post by 737diesel »

Just set the float height to 18, thinking that might help. Nope.
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Re: just another jetting question

Post by KDXGarage »

I would go to 40. Check the air screw there.
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Re: just another jetting question

Post by SS109 »

You said you have the needle a 1.5 turns out. Have you adjusted it for highest rpm to determine if it is correct and then to best throttle response for actual riding? What a lot of people don't realize is that while the pilot jet affects primarily idle to 1/8 throttle it does impact the entire rpm range to some degree. That's why it's imperative to sort your pilot circuit first and get it dialed in. So, what do you mean a clean idle? Is it bogging, hesitating, or ??? Was the bike at full operating temp? I know my bike loads ups a bit on the first ride of the day and takes about 30 seconds of riding to clear it out and then the throttle response is perfect for the rest of the day. Also, I've seen issues with people having the idle speed screw set too high (not the sir screw) and the bike actually isn't completely idling on the pilot jet circuit. Just something to check.

Good move on setting the float to 18mm so we know it isn't the problem. Well, if it's sealing properly anyway.
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Re: just another jetting question

Post by 737diesel »

I mentioned the needle at 1.5 as a starting point. I have been trying to obtain highest rpm with the screw, bike idles pretty well, but it can be hard to determine the change in rpm as the engine just seems to be loaded up. Yes, I am trying to follow the guide by starting with the pilot circuit first. I may be guilty of not having a fully warmed up bike. Idle screw is definitely in the lower half of its range. I will warm up the bike more thoroughly next time.
One other thing. The CEK needle is installed, but I have read on this site that it is a more rich than lean needle. Is this counterproductive if I'm trying to lean out what appears to be a rich setting?
I have been trying to find and compare all the posts here that have similar setups as mine: 40:1, new top end, reeds, FMF woods and Turbinecore 2, and mostly sea level (southwest WA). Finding a lot of guys with the 38,155, middle clip, type settings. I know, I know, every bike is different!
Again, thanks for all the help.
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Re: just another jetting question

Post by SS109 »

I've used the CEK needle now on two KDX's, a 200 and a 220, with great results. Just because it is a richer needle overall vs the factory needle isn't an issue. It can only supply what the main jet allows it to and whatever the pilot jet is adding. It's just a matter of getting the main and pilot dialed in and then the needle is easy IMO/IME. For the record, my current 220 is at a 148 main, 38pj, CEK needle in position 3, at 2000 above sea level, for temps above 80f.

I normally do all my jetting work at the staging area when dialing in a bike I haven't setup before. I start the bike up, let it warm up until its uncomfortable to touch the radiators, then go for a little ride to get it full warm and clear it out. Now the bike is ready for some jetting work. Yes, the engine is hot to work on now but that's how you want the bike to be for dialing in the jetting. After changing the jetting I'll fire it up, take a little spin, then install a fresh plug and do a proper plug chop run. Change the plug out right on the side of the road so as to not ruin the results of the plug chop.

If your having trouble distinguishing idle speed change, I might suggest picking up a cheap hour meter with the rpm feature. I know RMATV has them for around $25 and it makes it where you can actually see the rpm change. Mount it where you can read it while adjusting the idle mixture and idle speed screws.

That said, I'm beginning to wonder about the mechanical condition of your bike. It shouldn't be this hard to get it dialed in IME. By any chance have you done a leak down test on your engine since the top end?
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Re: just another jetting question

Post by 737diesel »

pursuing the leak down test on Monday. I didn't do one after the top end. I'll let ya know the results.
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Re: just another jetting question

Post by kdxdazz »

My experience with the CEK needle is it is absolutely useless, so rich my bike refused to idle even with a 32 pilot jet but I live in Thailand at elevation and hot and humid, the problem with running this needle is if your carb is on the older side(I didn't see anything in your post about a new carb) with a slightly worn emulsion tube this needle will just dump huge amounts of fuel at idle, the straight diameter effects idle by a large percentage. Back to the emulsion tube, you will read many comments about look at it to see if it is ovaled, this is simply incorrect, the emulsion tube only needs to be worn by 0.01mm to have an effect and that is not visible with the naked eye. Worn float parts make setting the float level difficult so I suggest the clear tube method as per the service manual. So in order of checking.... Jet block gasket, float level set using the clear tube method, put all jetting back close to factory spec and try both the factory needle and CEK needle to see which one runs better at idle to 1/4 throttle, this will give you some small idea if the emulsion tube may or may not be worn
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Re: just another jetting question

Post by SS109 »

kdxdazz wrote: 06:49 pm Jul 12 2020 My experience with the CEK needle is it is absolutely useless, so rich my bike refused to idle even with a 32 pilot jet but I live in Thailand at elevation and hot and humid, the problem with running this needle is if your carb is on the older side(I didn't see anything in your post about a new carb) with a slightly worn emulsion tube this needle will just dump huge amounts of fuel at idle, the straight diameter effects idle by a large percentage. Back to the emulsion tube, you will read many comments about look at it to see if it is ovaled, this is simply incorrect, the emulsion tube only needs to be worn by 0.01mm to have an effect and that is not visible with the naked eye. Worn float parts make setting the float level difficult so I suggest the clear tube method as per the service manual. So in order of checking.... Jet block gasket, float level set using the clear tube method, put all jetting back close to factory spec and try both the factory needle and CEK needle to see which one runs better at idle to 1/4 throttle, this will give you some small idea if the emulsion tube may or may not be worn
Some valid points you bring up. :supz:
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