Posts
24
Joined
12/23/2017
Location
Coraopolis, PA
US
bics56
12/21/2020 4:22pm
12/21/2020 4:22pm
Edited Date/Time
12/25/2020 6:05pm
Tomorrow I should be picking up a 2019 KTM 150sx. I found a nice clean stock bike with 33 hours. I been riding a TC250 two stroke for the last couple years (coming off of 10 years on 450's) and .this last year I got a yz125 to dabble in the small bore bikes for my second bike. I loved riding the yz and got intrigued by the 150sx and here I am now. I mostly ride for fun at local practice tracks. I may race a couple times a year in the +40 open class. So the bike is primarily for fun. Looking for some insight on what to expect for performance, setup, and light mods.
The Lectron carb makes a worthwhile difference.
A longer silencer also helps the over rev. My favorite combo on the 150 has been the stock expansion chamber with a turbinecore spark arrestor. In harescrambles I really noticed I was able to rev the bike further in each gear with usable power compared to a shorty.
If you can find a Keihin off the 2016 bikes and get it jetted correctly you can save some money vs having to buy a lectron. I jetted my 150 for average temps here in Fl (Hot and humid) and the bike has ran fine in FL, WV, NC, and TN in the winter. Just had to play with the air/fuel screw for a couple minutes at each place.
Be very cautious of torque specs for the oil drains, I learned the hard way that KTMs are more prone to ripping out threads compared to Jap bikes. More places to be careful are the top engine mounts and the bolts that mount the slave cylinder to the case.
Flush the fluid in the hydro clutch often. It gets dirty pretty quick with the abuse a clutch takes in a small bore. Clean fluid will make a huge difference at the lever in terms of feel. I do mine about every 20 hours.
Play with the adjustment screw for the Powervalve! They’re only a couple bucks a piece. I recommend starting with the red screw, get the head corrected for good fuel. I had my guy clean up the engine for around 102-105 octane to keep the bike reliable, and be able to run good fuel. I usually run a mix of leaded 110 and rec 90.
Have fun with the bike! The 150s are a blast, be sure to throw up a pic or two of the bike!
The Shop
With the stock 13t on my yz144 I noticed that in the lower gears 1st thru 3rd. It would spin up too fast and rev out quickly and wheel spin breaking traction easily. You would run out of gearing in the lower gears before you ran out of power.
So you ended up short shifting through the first three gears to quickly. You ended up being a gear to high because of this. The ktm 150 sx does this same thing with the 13t front sprocket. I'm going to put on a 14t front like i did my yz144.
When I did that to my yz144 it corrected the gearing ratio and brought it back to how it was. When my yz125 was stock. I'm pretty positive this will fix the sx 150's gearing. Going to a 14t front is like taking 3 teeth off the rear.
The older ktm 150's before 2016 came with 14t fronts.
2) I second the gearing advice. There is ample bottom but I was out of 2nd too fast IMO. Instead of gearing it down, I went up 2 teeth in the back. This paired with a shorty silencer made 3rd a 2nd on steroids. Pulls hard in tight corners and has that long pull you'd expect out of 3rd.
Also, there seemed to be a gap between 3rd and 4th with stock jetting. I would be pulling 3rd and feel the plateau, and with the rpms still on the pipe, feel like 4th took a bit to get back in the meat. There was this soft spot where I couldn't keep it pinging. The higher teeth in back solved that.
Other than that, I have 15 hours on mine that I picked up last summer. Running stock suspension with the 110 purple Sunoco leaded fuel mixed 50/50 with 93 - and the recommended Motorex oil at 32:1. Let's face it, these bikes get wrung out. I'll do things like Notch the slide and stuff that allow me to run it a bit rich up top.
I stopped using ethanol fuel all together after talking with an engine builder about how the percentage of ethanol content can lean the bike out.
To get a better feel I’d like to do a lap or two and bring the tool to the track do a full turn in or out so you can feel the difference of where the power band hits
Jet the mikuni or get a pwk. I didn't like lectron on my 150
https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/KTM-HUS-125-150-2…
Gearing wise if you want to go up one tooth in the rear or down in the rear get a whole new front, rear and chain. Bump up to a 14t front sprocket and get the rear accordingly to what you want to do in the rear. I've ridden them with stock, +1 and +2 and I felt stock was the best of the 3 and really wanted to go -1 in the rear.
The reason I say bump up the front is it changes chain angles and frees up the rear suspension under load and in back to back testing is noticeable. If you need help with the math on it let me know. Its kinda easy though. example: if it has 13t front and a 50t rear then its 50/13= 3.85. If you want to keep close to the same ratio it would be a 14t and 54t which would put you at a 3.86 ratio.
Chassis wise it also likes the Ride Engineering steering damper. It will help it from trying to climb out of ruts.
Get the suspension set up for you. The shock spring will be undersprung for anyone thats not 120lbs. The Ride Engineering link will transform the way the bike handles and cut down on the rear swap going hard through braking bumps.
My 21 all ready comes with the S4 needle jet.
I run my bike on trick 100 it's a 100 unleaded non ethanol fuel at 40:1 on 927.
I like to ride my 150 like a 125 and I have a 14t front coming. All ready did the jd jet block gasket swap.
Just don't want to squeak my new bike with only 5 hrs on it.
It runs okay right now but i may have gone the wrong direction. When I first got it, it had this bad rich burbling at 1/4 throttle. So i went down one on the pilot to a 27.5 and it helped a little bit. So i went to clip position #2 and it felt better. But this was in early August and it was 80 degrees.
The last couple times I rode it especially like a month ago and it was 34 degrees in the morning. It had the hesitation bog to the point of almost stalling out around 1/4 throttle. It got a little better when the temp warmed up. Oh yea and it seemed like more than usual it was hard to start. I know when it's really cold they are sometimes a pain. For that first start of the day but it was refusing at first.
Pit Row
I was thinking about just going the pwk route instead. Partzilla wants $134 for that 5.0 Suzuki slide. Jd jetting had'em listed for $75 but it's listed as back ordered.
I know the tmx - x style carb can be made good. But it was like night n day with my friends 06 cr 125 n 250 putting the pwk air striker on them.
It seemed like in 16 it ran better with the pwk. So why not just get one an put the 16 settings in it. Or is that the same thing jd jetting sales when you buy the pwk from him?
I rode my friends '18 250 sx with a lectron on it. It's the newest version and it ran good. But it really didn't seem that much or any better than my stock mikuni on my '21 250sx. So i wasn't that impressed by it.
The stic sounds cool but it's kinda expensive for just being a different jet metering block setup. That and it seems like it's still kinda in the testing stages.
RB designs can cut your stock slide to 5.0 for $25 if you google them.
With the jetting in the thread AJ posted, you're leaning out the slide and needle and can then run a pilot and main which are more in the correct range of what the bike needs because you're not trying to work around an excessively rich slide/needle combo.
Fixes this in-between decision to lean out jets. Trust me.
Works wonders on my 19 TC 250.
Re-jetted a friend's 150 SX (2017) -per the AJ]s specs
Fast A rider and he was beyond thrilled by how clean and crisp it is running now
Was so rich and gargling/inconsistent prior the mods.
We're both in FL so elevation changes not in the equation but large swings in temp and humidity and besides maybe A/S tweak if you're super finicky, these jetting specs are the best bang for the buck.
The TMX has been on YZ 125 forever and nobody ever complained about it.
KTM/Husqy just came up with some questionable stock settings
Post a reply to: Picking Up a 2019 KTM 150sx...What to Know