Recommended Jetting 2004 KTM 450 EXC

My 2004 KTM 450 EXC has been sitting idle for the past 5+ years and I've decided to get it back running. I called myself preparing it for long term storage so we'll see how that works out. I never was happy with the jetting. It came from the factory running lean. I rejetted the main and got it where it ran fine as long as I was hard on the gas, but it would run hot when I was just playing around. Anybody know the correct jetting for this bike for riding in the woods around Houston? Nothing on the engine side was ever modified from stock.


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I would try the kit from JD Jetting. Just put one in my 250xcf and it made all the difference in the world.

Bike had a bit of a flat spot with the jetting that was in it when I got it. Ran great once you were up in the rpm a good ways but when working real tight trails that hesitation and flat spot was annoying to me.

I had an issue when I first put the kit in as I was thinking it was running too rich as JD jumps 10 main jet sizes but the difference is his needle tapers.

Once got some emails working with JD, and my mind wrapped around the concept that a jump 10 jet sizes could still be lean. I went ahead and moved the clip down one more notch to the 5th notch and presto almost perfect.

Took it out today and did some fine tuning with fuel screw and idle and it is fantastic now.

Just arrived from riding CO and NM. I had the jets that the bike came with and the JD kit instructions. I was surprised that after adding a little idle to the bike at 10K feet it ran better than in Austin. Less power but also less backfires when I closed the throttle.
I rode to 12.5 K feet with out much issue.
Riding tomorrow . Will have to set the idle back down again. You guys think I should change anything on my carb? I really thought it ran great here the last couple of years.
( Sorry for the thread capture, though that the subject was similar)

Birdman44 said:

My 2004 KTM 450 EXC has been sitting idle for the past 5+ years and I've decided to get it back running. I called myself preparing it for long term storage so we'll see how that works out. I never was happy with the jetting. It came from the factory running lean. I rejetted the main and got it where it ran fine as long as I was hard on the gas, but it would run hot when I was just playing around. Anybody know the correct jetting for this bike for riding in the woods around Houston? Nothing on the engine side was ever modified from stock.


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I'm pretty happy with the JD kit I put on my 05 450 EXC.

In my experience comes from a lean condition. Lean causes a hot running engine also. I would go a little richer in steps till it stops.

Thanks for the replies. Looks like JD kit is the way to go.


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