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  • Writer's pictureCharles Lytle

Back at it! Rides 4-6.. Nitpicking..Jetting revisions, rants, and typos.

Whew! I had intended to stay more on top of the 17 250SX blogging than this but at least I was out spinning laps! She now sits with 7.5 hours on the clock!

I will need to go back and see where I left off in spec/ details after the third ride report. I'll start with jetting in the new-for-17 Mikuni. I had dropped the needle one clip position in attempt to lean out the bike a little bit and initially felt it was a good change. I quickly realized it wasn't. The bike went flat up top under full-load acceleration. The worst part about that is that the bike already has an early sign off RPM. It's still bone stock and I intend to expiriment with an Pro Circuit R-304 that'll be here very soon! Back to back against my YZ250, (which is jetted, piped, fresh top end and V-force reeds) the YZ's over-rev is night and day better. BUT! This isn't a fair comparison at all, stock KTM VS YZ w/ bolt on mods. Simply providing a basis for contrast. I want to make the 250SX over-rev like the YZ ultimately. Lastly, I've installed a needle that's 1/2 clip position leaner instead of a full clip position leaner. I'll be testing that this weekend. The goal is to maximize the OEM configuration before I start bolting crap onto the bike.

For you sea-level guys/ girls (we're at 2,500 ft in Boise, ID) I had a chance to hit E-Street and MMX in the Marysville, CA area a few weeks ago with the following specs:

SEA LEVEL Mikuni TMX 38mm. Main 450 (440 stock) Pilot 40 (42.5 stock) Stock needle 6BFY43-73, clip pos. # 3, with air screw about 2.5 turns out. Using 50/50 (race 101/ pump 91) and Castor 927 premix at 40:1.

***(The photo says 42.5 pilot, but I was using the 40 pilot. You'll see I'm great with typos while using the label maker too!)***

***Slow, and I can't type? Whatever...I have a new bike! My specs in Boise, ID***

It was hot out! But the bike ripped! It just lit up the rear tire every time the throttle was touched. I wish I had tried the stock 42.5 pilot too. Anyhow, the bike struggled for traction in the sandy soil at E-Street with the abrupt delivery. The 250 SX required many short-shifts to stay in the meat of the powerband due to it's early sign-off. The best part about getting to ride it at sea-level is that I now have a "feel" that I can chase as I continue to play with brass here in Idaho.

This weekend's test will include the following specs: Mikini TMX 38mm. Main 440, pilot 40, needle 6BFY43-74 (1/2 clip leaner), air screw test will be between 2.5 and 3 turns out. Using 50/50 (race 101/ pump 91) and Castor 927 premix at 40:1.

So concludes carburetor talk for now!

***Carb access on the KTM 250SX is a breeze. That goes for most KTM two strokes. I can pull the slide out of the top of the carb with the carb installed (7mm socket). Swapping brass takes only minutes!***

***Loosen the two air-boot clamps and roll 'er on over.***

***A half-clip leaner needle shown above. You can sorta see it....***

Moving onto the 48mm WP AER fork. I have found comfort at 153 psi. I'm a heavy 225lbs. It feels good for me, at my ability level. These forks are good! I can't seem to get them to scare me. They're pretty predictable. I haven't noticed any deflection, or unwanted/ sketchy, all-of-a-sudden bucks that result in a soil sample. Good stuff!! These forks, to me, are like the "air version" of Yamaha's KYB/ SSS stuff. I'm really impressed. They don't build up PSI over a 20 minute moto. My only gripe is a slight spike at the bottom of the's an air thing. I feel it most over, say, landing on the back side of a jump, and there's a big hole coming up. They give you a bit of a jar when there already way down in the stroke and you hit a good hole for example. Air isn't linear like a coil spring (Yamaha), so it's to be expected. Over three pounds lighter....what's not to love?

Again, suspension is specs might be terrible for you and you might hate these forks. But, they're not the air forks you're used to. No question there. Shock is great, no complaints! Went in on the high speed comp adjuster (I should really just loose weight) and got the G-outs to stop.


Here are a few pics in regards to things you should know about the KTM 250SX and other KTM's like it:

***My FREShmoto graphics are holing up well. they still look awesome and I love our logo in chrome. Hit us up to order a set as we are a registered dealer, or check out to see their other series. Awesome husband/ wife team, right here in Idaho!

***Shown: A filter with only 2.4 hours of ride time. Prepped track, low dust, doesn't matter. Keep 'em clean! Additionally, water can and will enter your airbox every time you wash...Like, a lot of water! Cover it up with a large zip-lock baggie if you make the mistake of cleaning your air filter BEFORE you wash your bike. This will apply to all or most 2016 models, as they all received this body/ frame change last year. The 250SX was the only bike that didn't get these updates until 2017.***

***At 7.5 hours, my wheels are starting to deteriorate. The graphics are holding up better than these wheels! I did find the "EXCEL" stamp in these wheels, but jeez. My two-year old set of TUSK wheels on the YZ have less rash than this and only a bit of silver from use. TWO YEARS!***

Lastly, the fuel breather line on the tank could use some attention. Some guys hate that it winds up and twists when it's tightened after a fill-up. Easy solution. simply set the cap back into the tank and "wind it up" one turn counter clockwise. Once you've done that, the breather will untwist back to it's standard position instead of one of those crazy-straws we drank from as kids. The thing I dislike about it is that fuel travels up the line to where its plugged into the frame, and sloshes fuel around inside if it. In short, it proceeds to drip out of the frame all over the hot exhaust pipe, creating a black goo. Needs a one-way breather.

That's all I've got for you guys this round! Hope you enjoy and I'll let you know how the new brass works out!

Thanks for reading!

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