KDX jetting advice needed

motoscooter · Jan 7, 2007

So I bought this 03 KDX 220R over new years from a dealership in Colorado. Brought it to Florida and I start hearing talk about needing to re-jet it and stuff. If this is the case, where the heck do I get technical info on what it should be? How do I determine what it has in it? I know that the main jet and pilot jet are involved and how to remove and replace them. But thats about as far as I can get on my own. Scared to ride it because Ive been told I could ruin the engine if its running too rich or lean. Do I have to re-jet it or can I simply make some adjustments to whats in there? :bang: Any help would be appreciated.

csmutty · Jan 7, 2007

motoscooter said:
So I bought this 03 KDX 220R over new years from a dealership in Colorado. Brought it to Florida and I start hearing talk about needing to re-jet it and stuff. If this is the case, where the heck do I get technical info on what it should be? How do I determine what it has in it? I know that the main jet and pilot jet are involved and how to remove and replace them. But thats about as far as I can get on my own. Scared to ride it because Ive been told I could ruin the engine if its running too rich or lean. Do I have to re-jet it or can I simply make some adjustments to whats in there? :bang: Any help would be appreciated.

If it is on the rich side which you can tell by a lot of smoke coming out of the exhaust then I wouldn't worry about it that much as it will not damage your engine. If it is on the lean side then you will have to worry aboout jetting but usually with KDX's they are very rich from the factory, but since you got this bike used I don't know if it is still factory jetting.

paab · Jan 7, 2007

colorado could be a high elevation rider, possibly someone leaned out the jetting a lot to correct. It may be dangerously lean for FL. I would pull the carb out and at least check the size of the main jet. It's stamped on the side of the jet and they are easy to remove. anything under a 150 might be worth changing out before riding.

steve.emma · Jan 8, 2007

anything under a 150 might be worth changing out before riding.

he is riding a 220 so assuming standard carb then main jet should be under 150. standard main is 145 from memory.
on my 220 i used 145main 42 pilot needle second clip from top and it ran really great at sea level.

paab · Jan 8, 2007

Oh, thanks for that, I forgot it's a different carb...

crhines · Jan 8, 2007

I have a 1999 kdx220 with pro-circuit pipe and airbox mod. I have tested different jetting combinations and ended up with 38 pilot, 145 main, and very top notch on stock needle at 1000 ft & 75 degrees. I couldn't tell much difference in performance between a 38 pilot and 42 pilot, it just spooged more with the 42.

motoscooter · Jan 13, 2007

Thanks to everyone for all the advice. I ended up with a 145 main and a 42 pilot. 2nd from top on needle. Im glad I asked the question because it had a 138 main and a 38 needle. Prolly would have casued me some issues especially when racing enduros. Gonna run it this weekend so wish me luck.

krazyinski · Jan 13, 2007

crhines said:
I have a 1999 kdx220 with pro-circuit pipe and airbox mod. I have tested different jetting combinations and ended up with 38 pilot, 145 main, and very top notch on stock needle at 1000 ft & 75 degrees. I couldn't tell much difference in performance between a 38 pilot and 42 pilot, it just spooged more with the 42.

WoW!! I was unaware a stock 220 ran that lean,I bought my 220 with a fresh Fredette rebuild with all his tricks I run a 40 pilot cgm needle on the 3rd clip 158 main along with FMF gold series pipe ,Amsoil 50-1.

adam728 · Jan 13, 2007

krazyinski said:
WoW!! I was unaware a stock 220 ran that lean,I bought my 220 with a fresh Fredette rebuild with all his tricks I run a 40 pilot cgm needle on the 3rd clip 158 main along with FMF gold series pipe ,Amsoil 50-1.

Once the carb is bored out the air velocity goes down a good deal, and therefor so does the "signal" or pressure change across the jets. Less signal means you need a bigger jet to get the same amount of fuel into the engine. If you took a 2 completly stock 220's and put a larger carb on one you would see the need to put much larger jets in it.

motoscooter · Jan 24, 2007

okay, so I ran the 145 main and the 42 pilot. And for the most part it snapped into attention and ran like a top. One small issue though. From dead idle, if i jump on the throttle, there is a hesitation in the first 1/8 th of a turn. Beyond that, it kicks butt. Im thinking it might be an air screw adjustment maybe? If it helps, im running a 40:1 mixture. What do you guys think?

paab · Jan 24, 2007

I think that's a needle issue. I was only able to tune it out to a small degree with the air screw, but a needle change dialed it out completely. I have a 200, so I can't help with a needle suggestion... Try lowering the needle by raising the clip one position at a time. If it gets better, then you need a leaner needle.

KDX jetting advice needed

motoscooter

csmutty

Uhhh...

paab

steve.emma

paab

crhines

motoscooter

krazyinski

adam728

motoscooter

paab

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