kdx unusual jetting question

[motofox2006]

Hi guys I've been looking aroiund different forums and sites to find the jetting recommendations for my 1991 kdx200 but everywhere says you should run the bike with 155 main 48 pilot 1173n needle in middle clip.

My bike ive been running like it is for over a year now (since I bought it) and the jetting is quite different to what people recommend. I have an FMF fatty pipe with the airbox lid modified. And I run a 158 main jet, 52 pilot and a 1172n stock needle in second from top clip position. It runs fine and has plenty of go but the pilot does seem somewhat odd in comparison to what people recommend.

I ride sand that can become quite thick in some places, And im using a premix of 40:1 with fully synthetic motul oil.

Anyone have any ideas on what I should be running or if it is fine as it is.
Also any settings that could be modified like the jet needle without replacing it.

All input appreciated, thanks

[2001kdx]

Go right to 155/45, fiddle with the needle, but you will likely still be rich. I am running the same mian as you, working out great, but i have a 45 pilot in there.

you have different slide than me... that might change jetting.

[motofox2006]

Do you have any suggestions for changing the settings of what I have now I dont wanna go buy more jets. And the pilot if that is to rich will that decrease throttle response. Thanks

[kdxquebec]

Hi!

Why do you want to change the jetting of your bike?

[scheckaet]

Have you done a plug chop test? are you runnning rich / lean?

[kdxquebec]

I run a 48 pilot,158 main,stock 1172 needle (3 clip from the top)

Boyesen power reeds and fmf pipe and muffler.

[2001kdx]

Why do you want to change the jetting of your bike?

To maximize horsepower, throttle reponse, and fuel economy.
I noticed better throttle response when going from 48 to 45 pilot.

[motofox2006]

Go right to 155/45, fiddle with the needle, but you will likely still be rich. I am running the same mian as you, working out great, but i have a 45 pilot in there.

you have different slide than me... that might change jetting.

What temperatures are you running your bike under I run mine at temperatures between 14 degrees and 25 degrees celsius and I ride thick sand so might need a little richer jetting than usual? does this influence what you said there or do you still think the same. Thanks

[2001kdx]

Yes, your sand riding will require richer jetting, but not as rich as you have it. i'm operating in 15 degrees celcius.

[motofox2006]

OK I might change it to what you say thanks for the advice.
I took the plug out yesterday and it indicated that it was running fine not rich, but this was not after a plug chop. Is that even remotely useful to look at the general appearence of the plug. Thanks

[scheckaet]

Is that even remotely useful to look at the general appearence of the plug. Thanks

useful? yes if the jetting is WAY off but I don't believe you could tell the difference between 1 jet size unless you do a WOT test

[Mr. Wibbens]

Stock jetting on a '91 is 150 main, 48 pilot

On my '92, I'm running a 148 main with a 40 pilot, DEK clip #3
See bike profile in my sig for the mods

I run mostly woods.

My one time riding at the Oregon Dunes (sea level) I ran a 158

[motofox2006]

Hello everybody, I rode my bike with the 45 pilot from the 52 this weekend and I think it gave me slightly better throttle response but the bike seemed to be running hotter is this normal???

[Indawoods]

Don't be leaning the mixture in the winter! Trying to sieze it?

[Mr. Wibbens]

If your pig rich to start with, I would not worry about it

I recently went from a 150 to a 148 and I have not seized yet

[Indawoods]

There's a 48 and a 50 between them ya know...

[Mr. Wibbens]

but a 48 is stock

Besides what's the worst that can happen?




Get the RB Carb Mod, with a 4o pilot, turns the KDX into a whole different animal