Jets Configuration

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#1
I have a '99 KDX 220R with stock pipe and jets. The Fredette mods have been done... porting/polish and carb bore +3mm on the keihen PWK33.. (36mm)

I am adding an FMF Burly torque pipe and Boyesen Rad valves. What jet sizes and notch settings will I need for this configuration?

Any help is appreciated :)

Cheers,
Armadas Racing
'99 KDX 220R
 

Canadian Dave

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#2
Exactly which pipe do you plan on installing? FMF makes two pipe for 95 to 01 KDXs. FMF IDs the KG-35 as the woods/torque pipe for the 200 and the KG-30 as the woods/torque for the 220 and the rev. for the 200.

With porting, larger carb etc it looks like you are looking for more power everywhere including mid to top end power. I don't know what kind of power delivery you're looking for but if your intention is to add power everywhere including higher rpms you'll want to be sure your dealer has ordered a KG-30. There is often confusion between the two because of the way they are identified. Though the KG-35 works great on the 200, which it was originally designed for, it does little for the 220 at higher rpms. The KG-35 works well on the 220 if you are in really tight condition where you're mostly running in 3rd gear of lower but if you find you do much riding over about ½ throttle or in open areas the KG-30 is often the preferred choice. The KG-35 certainly boost the bottom to mid power for he 220 but offers little gain over the stock pipe at higher rpm hence FMF reason for only list one pipe for the 220, the KG-30.

Once you've decided which pipe best meets you riding style, conditions etc be sure you order the pipe by its model number and not by its name to avoid any confusion.

Once we know which of the two pipe's you are installing we’ll be able to come up with a reasonable starting point for your jetting.

David
 
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#3
These were parts left over from the guy I bought the bike from, I just bought them a week ago. He mentioned the stock jets would make the bike run lean with the pipe. I sure hope it has the model number written somewhere on the pipe because that's all I got. He described it as the "torque pipe for the 220 which increases low to midrange power".... it also came with an FRP torque ring if thats any help. He was unsure of the jet sizes I need because I am also installing the Boyesen rad valves...

Anyhow, I'll take a closer look at the pipe tonight and see if I see a model # written on it somewhere.. i don't recall seeing one before tho.

Thanks Dave,
Armadas Racing
'99 KDX 220R
 
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#4
FMF model #

Armadas Racing,
The model number is on the mounting tab that mounts the pipe near the carb.
 
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#5
The writing on the inside of the mounting tab indicates FMF model:
029 K B 30

Thanks for the tip KDXDan..

Armadas Racing
'99 KDX 220R
 

Canadian Dave

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#6
You've got an FMF Burly rev pipe AR which will give you more power everywhere especially on top.

Try a 158 main, the stock needle in the second from the top clip position and a 45 pilot jet. Be sure to do a plug reading at WOT to insure you aren't running lean and fine tune things from there. A 158 main may be too rich or lean depending on what your engines porting specs are so be sure to do that plug reading your first ride out. You can find instructions on the JustKDX home page.


David
 
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#7
Well... seeing as how I have to buy jets I may just as well buy a 159, 158 and 157 (I believe 155 is stock), just in case... and a 45 pilot, and play around with it till I get it right.. The guy I bought the stuff said after, that I wouldn't have to modify the jets for the boyesen rad valves... just the pipe?

Thanks Dave.. you're very helpful as usual.

Armadas Racing
'99 KDX 220R
 

Canadian Dave

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#8
Main jets don't come in ever size. You'll want to pick up a 152, 155, 158 and a 160 to get a decent range of main jets.

I'd also look at a 42 and 45 pilot jet.

David