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This is what worked as a starting point on the '18 150.
Pilot 30
470 main
slide 5.5
needle 42-71 3rd clip from a 2019.
This link will show you how to mod the slide.
Jetting the 150
So... I'm keeping up with this thread.
For me, I swapped back and forth between my RM and his KX all day and I think I'm gonna inherit the KX and let the RM go down the road, with regrets and no hard feelings. I love the way the KX fits me.
The 125 pulls longer than the 150. After riding both, it almost feels like the 150 signs off a little earlier. There are a couple of sections of track where I could run the 125 between corners without shifting, but I had to shift the 150. I can see how some riders could feel that the 125 might be faster overall.
There is no doubt that the 150 pulls significantly harder, especially down in the lower RPMs. Both bikes must be singing to make power, but you can get away with a little more with the 150, and it lights up with less clutch.
Remember, that you can spend $700 for a 125 vs 150 cylinder/piston direct from KTM/Husky. So if you have one, you can switch to the other for $700. I believe many people forget this fact.
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The Lectron runs extremely crisply, in my opinion they are about perfect. I wish every KTM came with one. It takes about an hour or less to install, and on both bikes they started first kick and only required adjusting the idle. My son didn't really like his 125 until we got the Lectron on it. The only gripe I could have with the Lectron is that the choke is awkward to get too, but I end up using only on the very first start if the bike hasn't been run in a few days. I had the Mukini (on the 125) jetted exactly per the book, and kept going leaner and leaner, and it still wouldn't run cleanly throughout the whole RPM range.
We are at ~2500 elevation and ride in the 90s in the summer, so I don't feel we are at an extreme elevation or anything. We bought the 125 bike used with about 20 hours on it. The strange thing is the previous owner had his son riding it, and they didn't feel it had any jetting problems. Not sure if it degraded over time, or maybe it just never ran perfect from the start and they didn't have a good gauge of the bikes potential.
The forks were changed to AER in 17, so models before 17 had the 4CS forks, which we all know were terrible. With the AER forks, I feel that they work very well for these light bikes with lighter riders on them. I am 5'5" 165lbs and my son son is 5'7" 140lbs. I am slow intermediate rider and my son is beginner/junior speed.
For those weights and levels I think the fork is just fine. If you are substantially heavier or trying to win Lorettas, the fork might not be the absolute best, but don't let the naysayers detract too much from the fork.
I now have Cone Valves on mine (moved from my 450), and while the Cone Valves are better, they are not night and day better.
Lastly, people knock the air forks for having to check fork PSI several times a day. I feel that if you want to race moto, and don't/can't check your fork PSI several times a day, you got into the wrong sport.
Cons: top signs off way too early because it’s simply a 150 Cylinder on a 125 bottom end. It’s really not made to run on the bike making it a good woods bike and a pretty sucky MX bike.
If you want a solid 144 that is built to run like it’s supposed to run bottom to top, handles like a dream and has a shock better than KTM and forks better than Yamaha... buy a TM144.
https://youtu.be/8oPr891LJf4
He is the on on the right trying not to loop out.
Listen to this man and try his specs before spending a lot on any other carb
(I did in the past on my 17 TC with a Keihin swap)
My 19 with the Mikuni runs great and consistently now.
I did two outdoor nationals this year on a 150. I chose the 150 for more torque over top end knowing I could get more top through bolt on mods. I lied on here and all over the web about it being a 125 but I didn’t want any problems at tech at Millville. I even printed off come badass “Wiseco Inside” stickers to cover the serial markings on the cylinder. I don’t think anyone cared to even look at the bike in tech beyond the ultra cool sticker kit and plastics livery, but better safe than sorry when I spent a few thousand for 3 practice sessions and an LCQ. I almost got in at washougal!
Things I highly suggest with the 125/150:
1. Lectron carb. I don’t care what anyone says about their ways to fix the mikuni carb. I had the JD jet kit in my stock carb and that made it less shitty but the thing was still a wet blanket. Lectron sent me their carb built to my demands and as long as I ride a two stroke (forever) I will have a Lectron. Even if they deem me a seven layer loser and ban me from even buying their product, I will go onto the black market/dark web and steal someone’s information so I can clear their system to purchase a carburetor. It’s that good.
2. Wiseco racer elite piston. If you’re looking for light switch engine revving- this is where the conversation ends full stop. Single ring and light weight this piston is a P O W E R M A K E R. Especially on the 150. Get that fucking junk stock Vertex out of that bike right now.
3. Premium premix oil. K2 or Motul 800. And a lot of it. 24:1.
4. Renegade PRO 110+ fuel no questions asked (and I paid full retail for it that’s how much I believe in it over VP)
5. Vforce reeds will further atomize the fuel in a more consistent and controlled way over the stock reeds. The finer the mist the better the burn
6. BR9ECMIX plug. This is one output cooler than the stock 8 plug- which you’ll want because you’re revving the fuckin piss out of these tiddlers. This is a mandatory plug for all two strokes.
7. Replace the DOT4 brake fluid with DOT 5.1. It’s a stiffer fluid with less water molecules in the fluid. Less water=less sponge=higher boiling point. It’s a two stroke. You’ll use the brakes. Replace the fluid now.
8. PC pipe and whatever silencer you wish. I prefer the BUD silencer. Don’t waste your time with anything but a PC pipe.
Like all stock bikes there’s plenty of room to improve the bike to your own tastes. This bike is a tap dancer on the shifter. Shift up and let the bike roar.
Couple questions:
1. What gearing have you found gives the best spread of power? I'm currently running 13/49 on my '19 and have seemed to like it better than the stock 13/48 but am thinking about changing it up again. Interested to hear what you've found works.
2. PC pipe...have you tried an FMF and if so...why the PC over FMF? I'm still running stock pipe but have a FMF Powercore 2.1 silencer that I like.
3. What bars are you running? I'm still running the stockers but at 813mm wide, I feel like they're too wide for me (I'm 5'8"). Thinking of cutting them down to 803mm. Keefer said 813 is too wide which I agree with, but also said the stock Nekens are too stiff. Not sure I agree with that but since the '19 frame is much stiffer up front, wondering if a less stiff bend would take away some of that harshness.
4. Suspension...what did you upgrade or are you running the AER 48s? Definitely want to get rid of the mid stroke harshness and plan on getting some work done to them this winter.
5. I'm running 40:1 motorex...but 24:1!? Thats gnarly...Wondering what the idea behind that is and whats the difference you noticed.
Lastly, I run the Slavens HV Mule Lectron and LOVE IT. Kicked the mikuni out of my garage once I got the lectron. Amazing difference. V Force also made a nice difference.
Thanks for chiming in and answering my questions if you can... and that's AWESOME you ran a 150 in the nationals. Keep it up!
Cheers!
It's a pretty cheap to pick up a larger front sprocket and give it a try.
Pit Row
2. The PC is horsepower king. It’s also the heaviest gauge pipe tuned for motocross. It can take a beating.
3. Mika STV’s with the crossbar. I am a rare breed when it comes to hand controls because I literally do not hold on to the bike by the bars. My grips last forever. The Mika STV is the straightest tallest bar they offer. My levers are at 0°. Major key is I run the BRP top triple clamp with a 4 post rubber bushing bar mount- far superior to the stock 2 post that will slide out of position with the wrong gust of wind.
4. Factory Connection. I use their top of the line consumer products and lucky for me the Oklahoma office manager sees me ride often so Todd knows how to set up my bike. My forks are prematurely serviced and my shock is never serviced fast enough because I’m an over the back of the bike rider (I grew up on two strokes and it’s obvious when I ride them)- so my shock internals get beat up way before my forks need service. As for performance...unrivaled. I’ve ridden many many many brands of suspension revalve and nothing in my opinion is close to FC. they also test the absolute shit out of KTM’s.
5. I ride a lot of sand and a fair amount of mud/deep black dirt. The bike is always under load and I’m usually riding it above 11,000 RPM. Only one thing lubricates the crank: premix oil. I see no performance loss and am always more than satisfied with the longevity of my small bore cranks at time of replacement. Some would call it overkill. I call it safety net and peace of mind knowing I won’t be having any crank failures at 14,000 rpm. I also run my bikes just a cunt hair lean. It’s good to compensate for that with more oil.
Personally I think this 150 is one of the best motorcycles ever made. I used to think my 03 200sx was top- until I suited this 150 (which makes more peak HP than the 200 did) with all the aftermarket goodies to perform to my expectations.
Also a tip on the forks
Try running 135-138 lbs of air and stiffening the right fork up a little. The air is most pertinent in the mid stroke. Running less will soften that up- but you’ll need to compensate by running a stiffer clicker on the non air fork.
Did you have a Lectron when you were on the 250SX?
Namely the H series offers a 30%+ finer fuel atomization rate than the previous generation. The finer the “mist” the more cleanly the fuel burns.
Also a major perk of the Lectron is tuning. I live in Kansas City and a common saying amongs locals is “if you don’t like the weather- wait an hour”. Yesterday it was 67° and humid. Today the high is 39° and dry af. I can set up my Lectron for both days as easily as it is to adjust a normal air screw. Tuning the power jet on the intake side of the carb is a breeze. Before with the stock carb it was a guessing game and the 7 step process to pull a main jet. That’s all gone.
If you do a yz144, it won't come close to the ktm125, let alone the 150
To say a carb is fine because it works good on one bike is erroneous. The YZ 125 carb settings are okay. I had one. Pretty clean running. Not much power to speak of though.
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