Got a little seat time yesterday with some setup changes and happy to report that all changes were positive ones!
Sitting now with 3.1 hours on the clock.
Back at OMC MX track here in Boise, ID. Track direction was reversed too, so a nice mix-up.
AER 48's/ Shock:
Before riding, I installed the proper rear spring for my weight. This, coupled with a few more PSI in the front fork helped significantly with balance, predictability and rider confidence as one might expect.
-Sag is at 105mm with new 5.3 kg. rear spring -PSI is at 151, up from stock 148
-Fork height: center grove in clamps. (I read Factory Edition's equipped with the first sets of AER's didn't have a third groove/ height setting)
I will probably raise the PSI a pound or two just to see how it feels. Aside from that, the high speed compression (17mm nut) on the rear shock was a bit too soft in stock trim. I turned it in 1/8th turn and experienced less "G-outs" upon jump faces and hard landings.
This bike CARVES lines. The chassis is ultra quick and goes right where you want it to. Really happy with the way it settles into turns and carves a nice arc. It is much better handling than my YZ250. The YZ also has sort of an older style saddle, and seat config. and isn't flat or as easy to slide into position for turns like the KTM. I appreciate the YZ because I always know what it's going to do though. I'm too new to the KTM to say I trust it as much as the YZ in terms of predictability. I feel like it'll dial in nicely however. Right now, the KTM is a bit "busier" in terns of suspension action in general.
Onward, to jetting and revised carb settings!
Previously I was riding with the new Mikuni in stock trim:
Needle clip pos: 3rd down from top
Air screw: 1.5 turns out
Elevation: 2,500 ft.
Not impressive! Of course not, it wasn't right for our elevation so no surprise. On the YZ250, which is Keihin equipped, I find that even with sea-level jetting it doesn't behave erratically. It makes less power, and is dull but it doesn't flubber around the track or spooge.
The new Mikuni on the other hand has very prominent flaws between jetting circuits when it's not set up properly. At least in my experience which is limited ONLY to the KTM 150SX and 250SX I've had the pleasure of re-jetting.
New specs are as follows for 2,500 ft. elevation:
Main: 430 (440)
Pilot: 40 (42.5)
Needle clip pos: 2rd down from top (3rd down)
Air screw: 2 turns out (1.5 out)
Elevation: 2,500 ft.
Temps: 75-90 degrees lately
This info can also be found in your 2017 KTM owner's manual. Also, I'm now using 50/50 race pump 110 & 91 octane @ 40:1 w/ Castor 927 premix.
Huge improvement. Power is vastly improved and no spooge to speak of. It falls a little flat when wide open as I've yet to install the needle I need. Raising the needle clip (AKA lowering the needle) one full clip position is a bit overboard. The needle I ordered is only one-half a clip leaner, which should liven up the flat spot during WOT. Can't wait to try it!
New needle coming: 6BFY43-74
Beyond that, a flick of the air screw should also clean up the pilot circuit the rest of the way. I get a slight fumble from a dead stop launch and will need to test the range between 2 and 3 turns out.
Looking forward to my next rip on Wednesday night at OMC. Hopeful I'll have the new Mikuni needle by then!
If you're having a hard time locating carb parts for your "2017", just order parts for a modern YZ 125. They too sport the Mikuni carb.
Have great week guys! I'll report back soon!
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