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300 jetting

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I rejetted my bike for the lower temperatures, I just follow the chart in the KTM manual and it's pretty spot on.  My buddy is a local pro, he follows the manual jetting except running the needle 1 clip leaner than recommended.

 

After riding 48 miles in the woods last Sunday, here's what happened.  The bike ran well, but after the bike was warmed up for an hour, the it began to idle a little high, which in turn affected my riding every time I pulled in the clutch to brake-slide a turn.  I adjusted the idle down to a kitten's pur, but the lean sounding naanananaanana continued on a smaller level every time I pulled the clutch while riding at race speed.

 

So I raised the needle to the recommended specs last night.  Also I checked the plug, the tip was caramel colored and the rest was chocolate colored.  Would you all agree that it was running a bit lean??  I think that's also why I crashed at the end of the day on a natural terrain jump!!!!  Couldn't be MY fault!!!   

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I rejetted my bike for the lower temperatures, I just follow the chart in the KTM manual and it's pretty spot on.  My buddy is a local pro, he follows the manual jetting except running the needle 1 clip leaner than recommended.

 

After riding 48 miles in the woods last Sunday, here's what happened.  The bike ran well, but after the bike was warmed up for an hour, the it began to idle a little high, which in turn affected my riding every time I pulled in the clutch to brake-slide a turn.  I adjusted the idle down to a kitten's pur, but the lean sounding naanananaanana continued on a smaller level every time I pulled the clutch while riding at race speed.

 

So I raised the needle to the recommended specs last night.  Also I checked the plug, the tip was caramel colored and the rest was chocolate colored.  Would you all agree that it was running a bit lean??  I think that's also why I crashed at the end of the day on a natural terrain jump!!!!  Couldn't be MY fault!!!   

 

OH--Sunday was extremely humid, it rained over 1.5 inches Saturday (muddy riding, excellent traction though).  Humidity causes the bikes to run leaner because H2O vaporizes into oxygen, creating more air.  That could be a cause.

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Based on your description of the plug color it sounds like the jetting is pretty close to spot on. Maybe you're just a change in the idle jet is needed?

 

But it was definitely lean on desceleration with the clutch pulled in.  I dropped the clip, raised the needle one clip. 

 

I will say this though.  Instead of following the manual for the air screw, I just turned rich on the air screw until the throttle would turn clean off the bottom with zero bog.  But what I never took into account was that I NEVER idle the bike while riding, even on a long downhill.  Why should I adjust the bike to rip off the purring idle RPMs?  So I adjusted the air screw out to specs, and WOW does it run cleaner off the bottom, since it has more air now.  And what's even more important, when I'm begging for traction on a steep uphill, the RPMs engage sooo smoothly so I can torque my way up the hill.  Before, I had to hit the pit jet/needle RPMs to torque my way up a hill, but the bike is controllable and doesn't stall at lower RPMs now.

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But it was definitely lean on desceleration with the clutch pulled in. I dropped the clip, raised the needle one clip.

I will say this though. Instead of following the manual for the air screw, I just turned rich on the air screw until the throttle would turn clean off the bottom with zero bog. But what I never took into account was that I NEVER idle the bike while riding, even on a long downhill. Why should I adjust the bike to rip off the purring idle RPMs? So I adjusted the air screw out to specs, and WOW does it run cleaner off the bottom, since it has more air now. And what's even more important, when I'm begging for traction on a steep uphill, the RPMs engage sooo smoothly so I can torque my way up the hill. Before, I had to hit the pit jet/needle RPMs to torque my way up a hill, but the bike is controllable and doesn't stall at lower RPMs now.

Call me lazy. I went with the JD kit in mine. I think the JD kit allows for a larger span in variances that would require a jetting change with stock jetting. My plug is a tad on the dark side but its in no way oily. After a day of riding there is just a hint of spooge on the pipe. I'm okay with running a tad rich. The bike pulls like a Mac truck right now. I still may try to fine tune a little more but I don't see it as a must do. I'm on call this weekend so I can't ride and figured I would spend some time tuning it more. I'm going to put the yellow PV spring back in for sure. Next race is in two weeks and the bike is just an animal with the red spring and loose dry conditions.

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Call me lazy. I went with the JD kit in mine. I think the JD kit allows for a larger span in variances that would require a jetting change with stock jetting. My plug is a tad on the dark side but its in no way oily. After a day of riding there is just a hint of spooge on the pipe. I'm okay with running a tad rich. The bike pulls like a Mac truck right now. I still may try to fine tune a little more but I don't see it as a must do. I'm on call this weekend so I can't ride and figured I would spend some time tuning it more. I'm going to put the yellow PV spring back in for sure. Next race is in two weeks and the bike is just an animal with the red spring and loose dry conditions.

 

My buddy has recommended the JD kit to me as well because the needles cover a broader range of altitudes and temperatures.  The stock kit has a range of 160, 162, 165, 168, and 170 main jets, three needles, and it usually takes the stock pilot of 35 or one bigger.  This covered altitudes from 1-10,000+ ft, and temperatures from 0-110 fahrenheit. 

 

This equals 30 different combinations of these jets.  How many jets/needles come in the JD kit?

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My buddy has recommended the JD kit to me as well because the needles cover a broader range of altitudes and temperatures. The stock kit has a range of 160, 162, 165, 168, and 170 main jets, three needles, and it usually takes the stock pilot of 35 or one bigger. This covered altitudes from 1-10,000+ ft, and temperatures from 0-110 fahrenheit.

This equals 30 different combinations of these jets. How many jets/needles come in the JD kit?

JD kit consists of 3 main jets, one pilot, and 2 needles. I'm at work so I can't provide what jet sizes are included. I've only had the kit in my 300 for about 2 weeks and I've just been making small adjustments after each ride to lean it up a little bit. Right now its just starting to cool down in Tucson AZ so I'm just going to keep an eye on it until we fully cool off otherwise I think I'll just be chasing my tail.

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