I need help adjusting the jet on my bike

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trist007

Member
Oct 3, 2007
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I have a 2008 KTM 530 EXC-R. I bought it in Austin, Tx. They said that the bikes run lean out of the factory so they put in a new jet to make the bike run richer. Now I'm finding out that the bike is running too rich because the spark plug is fouling. I have the manual but it doesn't explain how to adjust the jet. I was wondering if someone could explain how to adjust the jet.

From my current knowledge about adjusting the jet, I'm thinking of detaching the fuel hose from the fuel tank to the carb then unscrewing all the bolts that are holding the carb down. I take the carb out and look for where to pull out that needle. Then I remove the clip from the needle and move it up maybe 2 spaces up to make it leaner. Then just put everything back.

Can someone correct me if I have the wrong idea? I got a few questions. How do I know which direction to move that little clip to make it leaner. I need a point of reference to know that I'm making it leaner. I'm assuming by moving the clip higher the needle goes into the carb deeper thus allowing less fuel to flow so it would run leaner. Also, can somebody explain to me the difference between the pilot jet and the main jet. I'd be adjusting the main jet? Which jet do you guys think that the dealership changed? Is the pilot jet the one that is just for idling? Thanks guys.
 
T

trist007

Member
Oct 3, 2007
105
0
Also, is it easy to disconnect the carb from the engine block? Also, when I put everything back, do I need to grease anything?
 

IndyMX

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Jul 18, 2006
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search for Jetting, and read up.

It's obvious you have no idea what is going on in that carb, and until you do, I'd not suggest you go near it with tools.
 

Shaw520

Damn Yankees
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The jets can be accessed from the bottom of the carb, without removing the carb from the engine. Loosen the clamps both front and rear of the carb, carefully twist the carb sideways to gain access to the bowl. Remove the bowl and you will see the main and pilot jet. No need to mess with the needle or the top part of the carb. I suggest you get a shop manual.
 
T

trist007

Member
Oct 3, 2007
105
0
Thanks. How do I know which jet is which? When I was at the dealership, they showed me one of the needles and how to move the clip to make it leaner. I'm assuming it was the main jet. Would I be adjusting both the pilot jet and the main jet? I'm pretty sure my bike is running too rich. I've only put the first 100 miles on the bike and the spark plug fouled. What's the harm in adjusting the jets? I wanna be able to do this on my own, instead of taking it to the dealership and spending a fortune. I know I need to get the service manual but I just don't have a lot of money to spend.
 
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trist007

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Oct 3, 2007
105
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Thanks, gonna read it right now. I pulled a search on jetting on this forum and it was really difficult to find a guide that explained exactly how to do it. thanks.
 
T

trist007

Member
Oct 3, 2007
105
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That read cleared up a lot, thanks. Anymore guides available? I need one that explains how to remove the jet needle.
 

Shaw520

Damn Yankees
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Main jet and needle are two different things, main jet is accessed from the bottom, needle is accessed from the top. Unless you are looking to change the power delivery character of you bike, you shouldnt be messing with the needle. You original post claimed you want to go leaner,.. To go leaner/richer, you would change out the main jet larger/smaller.
Do yourself a major favor and dont mess with anything till you've read up on everything and know exactly what you are doing when you get in there.
 
T

trist007

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Oct 3, 2007
105
0
Well here's the thing. When I bought the bike, the dealership said the bike came out very lean from the factory. So they replaced the jet needle with a thinner jet needle to make it richer. So, as for as I'm concerned, my carb has the stock main jet, pilot jet, and throttle slide. The only thing that is different is a thinner jet needle. They said using the stock needle would be too lean, so that's why I was thinking about just changing the clip position on the jet needle should be enough. The main jet should be lean enough. I ordered a the service manual on cd.
 
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T

trist007

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Oct 3, 2007
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I also bought a JD Jetting Kit. However, for now, I'm thinking about just changing the clip position to a leaner position on the jet needle.
 

Shaw520

Damn Yankees
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trist007 said:
Well here's the thing. When I bought the bike, the dealership said the bike came out very lean from the factory. So they replaced the jet needle with a thinner jet needle to make it leaner.
Click to expand...
this was probably the wrong move,... should have installed 1 size larger pilot jet, and 2 size larger main jet instead of messing with the needle.

There are so many different variations of needles, you really need to know WHAT they put in there before anyone could recommend. Just dropping the needle a notch or two could reak more trouble. Messing with needle position without a properly matched main jet can cause lean spots throughout the power curve, (throttle positions that may be lean at some points, yet too rich at other points. This can have long term adverse effects on the engine. (lean conditions cause excessive heat)
At this point I STRONGLY recommend that you get the proper JD kit for you location/elevation, and use the matching components recommended in the kit.
 
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trist007

Member
Oct 3, 2007
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Sorry, I meant to say they replaced the jet needle with a thinner needle to make it richer. Everything else is stock. Yeah I'm gonna wait for the JD Kit to come in and start asking questions about the carb setup in my area.

I live in San Antonio, TX (Elevation 650 ft) and ride around here. If anybody lives near San Antonio or Austin or near that elevation and has a ktm 530, I'd like to know the size of your jets, slider, and needle. I'm getting a JD Kit so I should have most jet sizes.
 
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trist007

Member
Oct 3, 2007
105
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I forgot to mention that I kept the stock jet needle. Maybe I should put that one in and raise the clip to the first position from the top. Here are the stock settings of my carb

Main jet 180
Jet Needle OBDZT(after I reinstall the stock needle)
Idling jet 48
Main air jet 200
Idle air jet 100
Cold start jet 85
Throttle slide 15

So is the idling jet is the same as the pilot jet right? Also what are the main air jet and the idle air jets?
 
T

trist007

Member
Oct 3, 2007
105
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I received the JD Jet kit and installed the jets appropriate to my elevation of 600 ft. I put in a 175 main and a 42 pilot. The bike had a 180 main and a 48 pilot before. I wonder why these bikes come soo rich off the factory. What's wierd is that the dealer told me that the bikes come really lean, hehe oh well. Anyhow, I tightened the main jet on a litttle too tight and it broke. The thread of the main jet is now stuck in that other piece that covers the jet needle. What is this piece called? Also, anybody know where I can purchase a 175 main jet and another one of those pieces that the main jet screws into? I don't wanna have to buy another JD Jet Kit.
 
Y

yamarider88

Member
Jun 24, 2007
153
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go to any shop in town and they should have them or the ktm oem store on motosport.com and look under carb optional kit and select the jet you need and then look under carb and order the other piece you need i believe it's called a nozzle?
 
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trist007

Member
Oct 3, 2007
105
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So I installed the 175 main and a 42 pilot along with the red needle at the 2nd position from the top (that came with the JD Jetting Kit). After several attempts at starting it, it finally turned on. Once it warmed up, I noticed that the engine would rise in rpms without me adding any throttle, then it would go back down to idle and then go back up after 6 secs, again and again. Do you guys think that it is now too lean?
 
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trist007

Member
Oct 3, 2007
105
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Well I put in the new jets, 175 main, 42 pilot, and the red needle that came with the JD Jetting Kit. For some reason, my plug fouls in a matter of mins. I don't understand, I made the carb leaner not richer. I take the plug out, spray brake cleaner on it and clean it with a wire brush. I put it back in, starts on the first kick, doesn't seem like it can idle, i give it some revs and then it dies. Then I can't restart it after like 50 kicks. I check the plug and it's all dark brown and dirty again. What's wrong?
 

Shaw520

Damn Yankees
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May 14, 2000
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if you're using the recommended JD combo ,..then I would think you need to look elsewhere,... set fuel screw, check for air-leaks between the carb and the cylinder, make sure you filter insnt over-oiled, (very restrictive), make sure you're running the right plug......
 
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