2018 KTM 300xc jetting

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5/26/2018 8:32 AM

First off, let me say I am terrible at jetting and am having issues with jetting on my 300. The bike runs rich at 1/4 to half throttle and I can’t seem to straighten it out. I jetted to KTM’s recommendation and it wasn’t even close and when I called their Tech Support I was told their recommendation should work. It was so bad the bike would barely run at 11000 feet. I ride between 7000 to 12000 feet and had a 2015 that ran great at these elevations. Slavens Racing is suggesting I purchase a Lectron carb but at over $500 I was wondering if there were other solutions out there? Also, I had an older Lectron on my 2015 and sold it because I feel the bike was running too lean. Does the JD jet kit cure problem? Is there anything else I can do? Photo
Any help is much appreciated.
Thanks

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5/26/2018 2:52 PM

The JD jetting kit makes a big difference. If you’re rich at 1/4 - 1/2 throttle, try dropping the needle a clip.

I tried the Lectron carb. If you want to make your bike slow as molasses, then get the Lecturd. I ended up putting a Keihin from JD on my TX300 and it flat out rips. Even better than the Mikuni with the JD jetting kit. That would be my recommendation if you have about $350 lying around.

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5/26/2018 3:57 PM

I have a few friends with 300's in SLC and they all swear by the JD jet kit.

I put a JD kit on my 2016 KTM 125 and it was night and day better than my Lectron.

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5/26/2018 4:55 PM

Thanks guys.

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5/27/2018 9:24 AM

Before any jetting should happen, you should check the reeds and at the very least shave the head... There have numerous accounts of poor quality control with the reeds and they also run a fairly wide squish which can be difficult to jet...

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5/27/2018 11:01 AM

Monk wrote:

Before any jetting should happen, you should check the reeds and at the very least shave the head... There have numerous ...more

True! I forgot about that. My 125 had a warped cage also. Check this video from Slavens Racing.

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5/27/2018 11:53 AM

Monk wrote:

Before any jetting should happen, you should check the reeds and at the very least shave the head... There have numerous ...more

CarlinoJoeVideo wrote:

True! I forgot about that. My 125 had a warped cage also. Check this video from Slavens Racing.

Very interesting. I was just watching a youtube video with Jay Clark and he mentions cutting the slide to lean the bike out.

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5/27/2018 4:06 PM

Have you tried leaner pilot jets? Changing the jets in these bikes is very ez....loosen 2 clamp bolts, spin carb to expose bowl...push throttle cable down to get more slack to spin carb.....I can change pilot & main on my 250 sx in 5 mins...the mikuni is more sensitive to temps/altitude ect. Stay consistent with your fuel/ oil mixtures. I would start with 1-2 step leaner pilot jet.

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5/27/2018 4:39 PM

It's the head that's the problem

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5/27/2018 5:41 PM

sandman768 wrote:

Have you tried leaner pilot jets? Changing the jets in these bikes is very ez....loosen 2 clamp bolts, spin carb to expose ...more

I did lean the pilot a bit. It didn’t seem to help. Maybe I need to go further.

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5/27/2018 5:43 PM

slipdog wrote:

It's the head that's the problem

Would you go with a Slavens Mule kit or something similar to solve the problem.

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5/27/2018 8:45 PM

slipdog wrote:

It's the head that's the problem

Vonripper450 wrote:

Would you go with a Slavens Mule kit or something similar to solve the problem.

I don't have any experience with the Slavens kit, but my last customer with a 300xc ordered a Lectron before he brought his suspension to me and he found it didn't really help so he called RK tek. The guy told him the same things I did so he ordered one and now he said his bike runs like a raped ape with the TMX and stock jetting.

Slavens kit may work well, I just can't say for sure.

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5/28/2018 5:43 AM

x2 on the RK Tek head. It really helped clean up the jetting, and the bike makes quite a bit more power. You can pull a higher gear everywhere with it.

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5/28/2018 5:52 AM

Cant hurt to perform squish test, RB designs web site has a good info on this subject. His head mod is under 100.00 I believe.

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5/28/2018 6:44 AM

Thanks again for all the help guys.

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5/28/2018 4:58 PM

I will also add that I had a lectron on my 250sx and never liked it.revved too slow and always felt the slightest bit off. Jd kit had the stock Keihin singing, thing sounded like and old factory race bike!

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5/28/2018 5:54 PM

Pirate421 wrote:

I will also add that I had a lectron on my 250sx and never liked it.revved too slow and always felt the slightest bit off. Jd ...more

Nice. I am thinking Keihin carb with JD jet kit and a shaved head after evaluating the comments and reaching out to a few offroad folks.

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5/28/2018 6:05 PM

Pirate421 wrote:

I will also add that I had a lectron on my 250sx and never liked it.revved too slow and always felt the slightest bit off. Jd ...more

Vonripper450 wrote:

Nice. I am thinking Keihin carb with JD jet kit and a shaved head after evaluating the comments and reaching out to a few ...more

1.) Check the reeds for poor quality. Look for any gaps, chips, etc... This mod is free if everything checks good. If not, buy a Boyesen setup as it's a complete unit.

2.) Check the squish with some Rosen Core. If the gap is too large (which I'll assume is going to be too large) shave the head which should cost you less then a $100 depending on the shop. Because of the elevation you mention, you should not have to reshape the dome.

3.) Buy a handful of Mikuni brand Jets. Cheap off-brand ones never seem be of good quality and can range. Mikuni units will be on spec everytime. This will cost you maybe $50? And because you ride at high elevation you'll need only leaner (smaller jets). Do a couple plug chops and your golden... The JD unit is great as it take alot for the guess work out but it doesn't always mean it will be perfect...

If you're feeling really spendy, go buy a Lectron as it will do better then even the best jetting...

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5/29/2018 8:10 AM

Pirate421 wrote:

I will also add that I had a lectron on my 250sx and never liked it.revved too slow and always felt the slightest bit off. Jd ...more

Vonripper450 wrote:

Nice. I am thinking Keihin carb with JD jet kit and a shaved head after evaluating the comments and reaching out to a few ...more

Monk wrote:

1.) Check the reeds for poor quality. Look for any gaps, chips, etc... This mod is free if everything checks good. If not, buy ...more

Thanks for the help. What is interesting is I bought my last 300 used, and the previous owner had put a shaved head and VForce reeds on it. He must have installed that stuff for a reason. That bike ran excellent though.

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5/29/2018 9:18 AM

Why not just swap the jetting and slide like we've done on the 250's? Less work and cheaper than swapping a carb on it. There is the jetting thread just below this one right now and has a lot of information.

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2018 KTM 250sx
Instagram CamaroAJ

5/30/2018 6:54 AM

I've had jetting issues with my 17 300 Six Days since day one. Have the JD kit and I'm tired of swapping jets and needles. Put the V-Force reeds in day one because the stock reeds were warped. Bought the Lectron but have not put it on yet. Buddy has same bike with Lectron and it works Perfect.

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5/30/2018 2:38 PM

WFO wrote:

I've had jetting issues with my 17 300 Six Days since day one. Have the JD kit and I'm tired of swapping jets and needles. Put ...more

A lot of the folks around Colorado are pro Lectron. I think I’m going to give the Keihin a try with the JD kit. It is $320 and the Keihin on my 2015 worked well. I was able to ride a pretty wide range of elevation and keep the bike running well. Let me know how the Lectron works out.

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5/30/2018 5:14 PM

I went with the JD keihin on my tc 250. I ride at sea level to 4000', and don't even have to touch the idle screws and haven't noticed a difference in performance. well worth it IMO.

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