OMC motocross track in Boise, Idaho. Lots of elevation change, big sweeping berms, and ski jumps form 30-65' or so. Some fast sections uphill and also tight turns in low corners.
1.9 Hrs on the clock
Stock jetting on the new Mikuni (was Keihin until this year) was as follows:
Needle clip pos: 3rd down from top
Air screw: 1.5 turns out
Elevation: 2,500 ft.
Temps: 75-90 degrees lately this August
After my second hour on the new 250SX and some tweaks with the carb, I got a chance to open her up and hit some MX. First time REALLY jumping the bike and twisting the throttle back.
I lowered the needle one clip position from stock (now in the 2nd down position). It was a little fat and had some fumble right between where you come off the pilot jet and start riding the needle. This helped a lot with the fumble. However, it seemed a little more flat in the middle overall. I'd like to try a 1/2 clip leaner needle instead or whatever MXA recommends when this month's issue comes out.
***NOTE*** This exact needle clip adjustment cleaned up the same exact stutter on a 2017 KTM 150SX we had in the shop here a week earlier
The KTM came with a few other jets and a needle that was "richer" so not so helpful for me at the moment. Maybe save that for sea level AKA Zaca Station!
Next, i turned the air screw to 1.75 turns out: another small improvement, so I will try 2 turns out next trip to the track.
As for the rest of the bike, it handles very well. for a two stroke it sure carves ruts with a planted authority up front. It doesn't "steer with the rear" as much as some other two-strokes in my opinion.
Ok, ok, the forks. the new AER 48 air fork. Air in one tube, valving in the other tube. I cannot give this a proper review until I get the new rear spring for my weight. I've also limited myself to small clicker adjustments since it'll all chance again when i plop the new spring. The small changes I have made however, did make a difference. The bike is receptive to small two click adjustments.
Stock PSI is 148psi. KTM recommends using the clickers primarily before you add or remove PSI from the fork tube. I'm a big dude and I most certainly bottom these forks in stock trim/ air pressure.
There are roughly 30 clicks of adjustment for compression and rebound in the fork. I'm on the firmer/ slower side of things already and can see myself needing more dampening still.
When the new spring comes in I believe the added forward bias will make the forks even more prone to going through the stroke at the prescribed 148psi. It seems like I'll need to bump up the psi. a pound or two.
Having said all that, they feel like pretty dang good forks. They're nice and linear until the bottom of the stroke where they seem to want to spike in pressure a little bit. It only feels "under sprung" but the dampening doesn't feel notchy or like anything I have read about the 4CS fork.
Other than that, this sucker carves lines with precision, stops on a dime and makes really good, smooth power for a two stroke! Even being a bigger guy, the bike has very neutral controls that don't have me felling cramped into the cockpit at all. I really enjoy it so far.
Thanks for reading! More to report soon!
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