I just bought a KDX200

[nzspokes]

Blue smoke on full throttle doesn't ness mean too rich like black smoke on a 4 stroke. And you are proposing 4 jet sizes smaller. Move with caution try a size smaller and see if it runs better. Same with the pilot, try a 38 first. 5 half turns or 5 full turns? That woul be too far out and airleak territory.

I just found a 150 I will try and the 35. Im getting tons of splooge as well.

Yeah 5 full turns, long way out.

[nzspokes]

This is my plug with current jetting.

Sent from my GT-I9300T using Tapatalk

[F5 Dave]

I feel a I seized my bike thread coming on and bloody 2 strokes rant.

concerned enough that I looked up my archives. On my 91 (89-94 the same) I was running a 45 /152 and either R1173N or 1172, can't remember .had boysen reeds as well. This jetting change from std cleared it up immensely .

I can't see why on nz gas you should have wildly different jetting.

You out never did respond about ovality of needle jet. You can't jet around this problem. Most bikes seize with closed throttle.hence pilot.

[F5 Dave]

Plug photo means nothing. Really nothing. You can only check main full throttle and only under controlled circumstances. Just pulling it out won't work.

Im im probably coming across as a dick but I'm really concerned that it will cook itself. 5 turns of airscrew is about 2 more than you should ever try, it will be ready to fall out and leaking as well

[nzspokes]

Plug photo means nothing. Really nothing. You can only check main full throttle and only under controlled circumstances. Just pulling it out won't work.

Im im probably coming across as a dick but I'm really concerned that it will cook itself. 5 turns of airscrew is about 2 more than you should ever try, it will be ready to fall out and leaking as well

Mine is an 06 so slightly different motor. Im going to run it up this afternoon and see how it sets up on the 35. Its easy to change back so if Im at all not happy I will do so.

Below is the guide Im using as the base for tuning it.

The only way to know what jetting changes you will need is by trial-and-error. No one can give you jetting specs, because every bike is different,

every rider has a different style, and jetting is totally weather dependent. Unless the person telling you what jets to use is riding an identical bike,

on the exact same track, at the same time, his recommendations are meaningless.

Jetting is fairly simple, and is a useful skill to learn if you ride a two-stroke and want it to perform at it's best.

It's very important that you start with the pilot circuit. The reason is simple. The pilot circuit affects the entire throttle range. When you are at

full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your

engine is receiving.

Before you start to rejet your bike, you need a clean air filter, a fresh

plug (actually you need several plugs to do plug-chop tests for the main jet), and fresh fuel. One important detail: Make sure the engine is in good

mechanical condition. If your engine has a worn top-end, fix it first. Trying to jet a worn out engine is a waste of time. The same goes for

reeds that don't seal properly, and a silencer that needs re-packing. Worn reeds will mimic rich jetting, and worn rings will mimic lean jetting.

Before you start the jet testing, install a fresh plug. Set the float level to the proper specs, an incorrect float height will affect your jetting all

across the throttle range.

Warm the bike completely, and shut it off.

As already stated, start with the pilot circuit. Turn the airscrew all the way in, then turn it out 1.5 turns to start. Start the engine, and turn the idle

screw in until you get a slightly fast idle, or hold the throttle just barely cracked, to keep the engine idleing. Turn the airscrew slowly in, and then

out, until you find the point where the idle is fastest. Stop there. Do not open the screw any farther, or your throttle response will be flat and

mushy, and the bike may even bog. This is only the starting point, we will still have to tune the airscrew for the best response.

Now is the time to determine if you have the correct pilot installed in your carb. The airscrew position determines this for you, making it very

simple. If your airscrew is less than 1 turn from closed, you need a larger pilot jet. If it is more than 2.5 turns from closed, you need a smaller pilot jet.

Once you have determined (and installed it if it's necessary to change it) the correct pilot jet size, and tuned the airscrew for the fastest idle, it's

time to tune the airscrew for the best throttle response. Again, make sure the bike is at full operating temperature. Set the idle back down (the bike

should still idle, despite what you read in the Moto Tabloids), and ride the bike, using closed-to-1/4 throttle transitions. Turn the airscrew slightly in

either direction until you find the point that gives you the best response when cracking the throttle open. Most bikes are sensitive to changes as

small as 1/8 of a turn.

The airscrew is not a set-it-and-leave-it adjustment. You have to

constantly re-adjust the airscrew to compensate for changing outdoor temps and humidity. An airscrew setting that is perfect in the cool

morning air will likely be too rich in the heat of the mid-day.

Now, it's time to work on the needle. Mark the throttle grip at 1/4 and 3/4

openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a

notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle)

until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong.

Last is the main jet. The main jet affects from 1/2 to full throttle. The easiest way to test it is to do a throttle-chop test. With the bike fully

warmed up, find a long straight, and install a fresh plug. Start the engine, and do a full-throttle run down the straight, through all gears. As soon as

the bike tops out, pull the clutch in, and kill the engine, coasting to a stop. Remove the plug, and look deep down inside the threads, at the base of

the insulator. If it is white or gray, the main is too lean. If it is dark brown or black, the main is too rich. The correct color is a medium-dark mocha

brown or tan.

Once you have a little bit of experience with jetting changes, and you

start to learn the difference in feel between "rich" and "lean", you'll begin to learn, just from the sound of the exhaust and the feel of the power, not

only if the bike is running rich or lean, but even which one of the carb circuits is the culprit.

The slide is also a tuning variable for jetting, but slides are very expensive, and few bikes need different slides, so we won't go into that

here.

[F5 Dave]

Ahh bike SIG says 06. For some reason I thought you had an oldie. A mate just bought a 93.

He explains the sparkplug method. Any deviation from that invalidates the test.

[nzspokes]

Just did the idle jet test and found the highest idle speed was only 1/2 turn. So I have found I need 38 then. Have put the 40 back in and a 150 main.

Will take it up to the Sandpit tomorrow am for a blat.

[gwynfryn]

looked up my old kdx notes and I ran 42/155 and just moved the needle for summer/winter, Auckland sea level.
06 200
40:1
rad valve
full fmf
no air box lid

It has been warm lately so a 150 may not be far off but I like the security of a slightly fat top end for woodhiil sand.
Don't be fooled into jetting by the amount of spooge.

[nzspokes]

but I like the security of a slightly fat top end for woodhiil sand.
Don't be fooled into jetting by the amount of spooge.

Why the fat top end?

Our spec is very close except im on a PC system and Boysen reeds.

[Reckless]

Why the fat top end?

Our spec is very close except im on a PC system and Boysen reeds.

I run fat out the sandpit too with my KTM200, Copperish in the inner and wetish around the outside ring. Different two stroke oils will run different colours.
Good Fat power not thinner power with a dry plug like I'd run when I was karting in my 125 shifter.
I get lazy and leave it like that summer and winter just tend to give the power valve adjuster a turn if I want to take some sting out of it if I ride wet clay.
Seldom touch the Air screw, it starts and goes well so just leave it. I reckon the above gives me way enough power for trail riding even on the mx track at Ardmore. Running fat (slightly rich) extends the rebuild time as well.
I usually do ring and measure up 50-60 hours but Danger on here was still running good power in his 2hundy after 200 hours untouched.
I cant see a KDX 2 smoker used for trails should be any different unless you want it on song for every weather and track condition everytime you go out?
Quite Frankly I cant out ride my bike even when its set up lazy. Actually climbs better without the 100% 2 stroke sting coming at ya all the time.
Anyway each to their own LOL

[nzspokes]

I run fat out the sandpit too with my KTM200, Copperish in the inner and wetish around the outside ring. Different two stroke oils will run different colours.
Good Fat power not thinner power with a dry plug like I'd run when I was karting in my 125 shifter.
I get lazy and leave it like that summer and winter just tend to give the power valve adjuster a turn if I want to take some sting out of it if I ride wet clay.
Seldom touch the Air screw, it starts and goes well so just leave it. I reckon the above gives me way enough power for trail riding even on the mx track at Ardmore. Running fat (slightly rich) extends the rebuild time as well.
I usually do ring and measure up 50-60 hours but Danger on here was still running good power in his 2hundy after 200 hours untouched.
I cant see a KDX 2 smoker used for trails should be any different unless you want it on song for every weather and track condition everytime you go out?
Quite Frankly I cant out ride my bike even when its set up lazy. Actually climbs better without the 100% 2 stroke sting coming at ya all the time.
Anyway each to their own LOL

Fair call thinking about it. I do find on slow climbs in the sand its hard to keep the revs down and as soon as it comes on pipe it digs a hole. I may just go back to my 40/155.

Im going to order a thumb airscrew from the UK though just to make life easier. I can adjust when the power valve comes in which for my next ride I may soften it right off.

But I do like it when its singing on the pipe.

I do want a LH rear brake though. I have a plan to make it which I will start on today if the weather stops me going to the sandpit.

[nzspokes]

Well I have a functional LH thumb brake. Will refine it with some stronger parts but it seems to be able to hold the bike with the back wheel locked. I doubt it will lock the back wheel when riding but I dont want that anyway. Will post some photos when Ive done a bit more work on it.

[F5 Dave]

Cool, often think about one, be great as traction control in the slop.

[nzspokes]

Another wee blast up Woodhill today.

Played with the fuel screw and the sweet spot is at 1 1/4 turns out. So I really need to drop to a 38 idle. Mid felt fine. Top end flat with the 152 so will go back to a 155. Didnt sit her at high revs in case it was to lean.

Need to re-valve the KX forks. Not getting anywhere like full travel and its pounding me. Spring rate looks good from sag settings so still to much comp damping.