Posts
178
Joined
9/27/2021
Location
Fresno, CA
US
Edited Date/Time
3/2/2022 10:04am
Hey everyone
I’m starting the build of my 2019 KTM 125sx (kind of). I am 32 years old with a good job so I’m spending that cash (don’t worry old guys there a crap ton in retirement too). I race in the 30+ expert class in Over The Hill Gang member of the valley chapter. This year I’m racing all 5 national rounds for the first time ever. So I decided to build my bike just for that, as open classes I’m racing against pretty much 99% 450’s. Previous years I’ve raced a 250sx and done well. I rode my moms 150sx and honestly had so much fun I had to have one. Sold my 250 and got this 125sx. I’ve enjoyed it but it does slack a little bit on bottom.
Current bike setup:
2019 KTM 125sx
VHM head
V force 4 reeds
Bills Pipe and silencer
Vortex ECU
Mikuni with AJ’s mods
Race tech gold valves (pulled from my 250 so a bit stiff)
Overall the bike is good and honestly the carb mods and Vortex have been huge changes to the performance of the bike. With that said I still love a 150sx due to the extra bottom and that’s what’s going to happen.
Incoming mods:
Engine:
150sx cylinder
Vertex piston
Phathead racing head with race fuel insert (also standard available)
F1 Moto power valve arms
Polished power valve
VHM middle inertia crankshaft
Koyo hybrid ceramic engine bearings
OEM replacement bearing for the odd sizes
Nihilo Concepts Billet Water Pump Impeller
Vortex ECU
Bills Pipe
Dt1 billet cage
Dt1 filters
OEM clutch pack
Moto Hose White Rad Hoses and Y Hose
Maxima fluids
Chassis:
Ride Engineering Triple Clamps Non Split
RT gold valves
MXT A48R air chamber
MXT shock triple adjuster
MXT Tank Res
XTrig preload adjuster
Mika bars
Renthal intelli levers
Guts Phantom Seat Foam
Some Ti Hardware
Carbon Fiber mud flap
Carbon Fiber Frame covers
Carbon Fiber engine mounts
Stock wheels and eventually a set of Tusk or SM PRO wheels
Either starcross 5 or Hoosier tires
Standard tubes
Acerbis black plastics
OlmyCreations Graphics
Stainless foot pegs
So the main focus is engine performance with a little weight loss, nothing too crazy there. Ideally I’d send the engine to PC for porting to have a little more over rev. But since I have the vortex ECU I wanted to see it’s effects on the 150 as I’ve seen what changes ignition can make to a 125 it might give enough over rev without the port work.
I’m keeping the 125 cylinder setup as a spare just in case as a 3 day race weekend who knows.
The chassis setup is mostly geared towards the suspension for my weight (190lbs and dropping). The suspension from my 250 is a bit stiff and over sprung in the rear causing some extra kick in the rear along with some poor handling under braking into corners.
Honestly I wouldn’t have even done triple clamps except I transferred them from my fathers bike who passed a few years back. Same with the intelli levers; those also had been his so some parts with meaning.
At this point I have the bike completely stripped down to the frame and the engine completely torn down. Next I’ll begin the assembly of the engine.
Chassis Stripped
Engine Torn Down
Engine Cases Degreased
Anodizing Stripped
The goods
I’m starting the build of my 2019 KTM 125sx (kind of). I am 32 years old with a good job so I’m spending that cash (don’t worry old guys there a crap ton in retirement too). I race in the 30+ expert class in Over The Hill Gang member of the valley chapter. This year I’m racing all 5 national rounds for the first time ever. So I decided to build my bike just for that, as open classes I’m racing against pretty much 99% 450’s. Previous years I’ve raced a 250sx and done well. I rode my moms 150sx and honestly had so much fun I had to have one. Sold my 250 and got this 125sx. I’ve enjoyed it but it does slack a little bit on bottom.
Current bike setup:
2019 KTM 125sx
VHM head
V force 4 reeds
Bills Pipe and silencer
Vortex ECU
Mikuni with AJ’s mods
Race tech gold valves (pulled from my 250 so a bit stiff)
Overall the bike is good and honestly the carb mods and Vortex have been huge changes to the performance of the bike. With that said I still love a 150sx due to the extra bottom and that’s what’s going to happen.
Incoming mods:
Engine:
150sx cylinder
Vertex piston
Phathead racing head with race fuel insert (also standard available)
F1 Moto power valve arms
Polished power valve
VHM middle inertia crankshaft
Koyo hybrid ceramic engine bearings
OEM replacement bearing for the odd sizes
Nihilo Concepts Billet Water Pump Impeller
Vortex ECU
Bills Pipe
Dt1 billet cage
Dt1 filters
OEM clutch pack
Moto Hose White Rad Hoses and Y Hose
Maxima fluids
Chassis:
Ride Engineering Triple Clamps Non Split
RT gold valves
MXT A48R air chamber
MXT shock triple adjuster
MXT Tank Res
XTrig preload adjuster
Mika bars
Renthal intelli levers
Guts Phantom Seat Foam
Some Ti Hardware
Carbon Fiber mud flap
Carbon Fiber Frame covers
Carbon Fiber engine mounts
Stock wheels and eventually a set of Tusk or SM PRO wheels
Either starcross 5 or Hoosier tires
Standard tubes
Acerbis black plastics
OlmyCreations Graphics
Stainless foot pegs
So the main focus is engine performance with a little weight loss, nothing too crazy there. Ideally I’d send the engine to PC for porting to have a little more over rev. But since I have the vortex ECU I wanted to see it’s effects on the 150 as I’ve seen what changes ignition can make to a 125 it might give enough over rev without the port work.
I’m keeping the 125 cylinder setup as a spare just in case as a 3 day race weekend who knows.
The chassis setup is mostly geared towards the suspension for my weight (190lbs and dropping). The suspension from my 250 is a bit stiff and over sprung in the rear causing some extra kick in the rear along with some poor handling under braking into corners.
Honestly I wouldn’t have even done triple clamps except I transferred them from my fathers bike who passed a few years back. Same with the intelli levers; those also had been his so some parts with meaning.
At this point I have the bike completely stripped down to the frame and the engine completely torn down. Next I’ll begin the assembly of the engine.
Chassis Stripped
Engine Torn Down
Engine Cases Degreased
Anodizing Stripped
The goods
I'm going to start racing OTHG this coming year for the first time. If I see the bike I'll come say what's up!
The Shop
Oh and to Bruce looks like you either deleted your posts or they didn’t post but I read the replies on email. So mods wise I tried to go towards what has evidence of working. The bills pipe and silencer came on the bike and seem to have good though limited feedback. Exhaust outlet seems similar to the PC shorty which is what I’ve been wanting to buy but is out of stock everywhere.
It does seem the STIC is the way to go but for $800 it’s steep (not that I haven’t spent more than that elsewhere) especially when the Mikuni is pretty good now and there’s rumors of STIC coming to it eventually. I may swap it at some point but right now I’m moving my budget to consumables for the year.
Not sure how the Race fuel head insert will react as it may kill the over rev more which if so I do have the standard insert to swap in and gaskets to see which I like more. The phathead came with my cylinder I’ve used VHM prior so we will see.
The Crank per stankdog is a good add on so I figured I’d give it a try. And the vortex CDI I’ve enjoyed on the 125 if not just for different power delivery.
I’m curious how it will run I at least have ridden other 150’s stock and with exhaust to see how it goes. Not sure if dyno tuning will be in the cards.
Edit: I might be able to make a dyno day happen as I plan to take the TTR for a test on one so maybe I’ll just pay the extra to take this bike as well. Though the tire situation sucks lol.
Fwiw, stic does more than anything put together . Pete Payne of heavy duty racing is making the inserts for the oem head, because stock squish is quite high.
I ride argyll quite a bit so, but I wouldn't take my 150 out in 45 Nov lol. We have a 125 setup the same as well, it's my kids bike and he does ok but he's a crap test rider than can only tell a flat tire when it's hanging off the rim.
I've just got fed up with aftermarket stuff not fitting so I've become a bit cynical. Especially with a bucket of cracked fmf pipes.... although the fatty was one of the few things that made slight improvement on dyno.
Good luck and have fun. A friend of a friend raced argyll last time on a early alum yz125 and he won internediatebon it and watching that was fhe highlights of the day
On the mikuni , mine is dialed per AJ, digger thread. At the time, I couldn't get a leaner slide so I cut the stock one. I was worried I didn't take enough out, but luckily I didn't! Because when the 5s were off backorder, I tried one and it was too lean slightly.
Fwiw VP T2 and STIC metering block the bike js a wild ride.
This will be my first full year with OTHG, so I’ll see you out there.
I run Sunoco 110 regular leaded with Super M 40:1 it’s been good fuel for me and I’m able to get it at a decent price from a local distributor and know the sales guy. I have used T2 before and it is good fuel just I have to pay dealer markup on it locally at about $20-30 more a 5 gal pail.
Unfortunately all the dynos around me are sportbike and Harley guys. I have to drive a few hours for something Moto specific. Which I’ve debated on doing at some point but we will see. I value time at home these days. I’d like to get a map specific for my set up but time and money.
I’ve raced a 250sx the last few years with good success. I have not raced the 125 I planned to but a bad crank seal melted the piston skirt at cal city. And after that we had our first kiddo which I’ve let Moto take a back seat the last year and a half. Ill find out how it goes in a few short months when I stack it up with the guys I’ve raced in the past. I’ll definitely have to work harder than before but with my experience on a 150 with them at practice I should still be having fun and thats what matters.
Do the vortex "only" add overrev ?
I have also bought rekluse torq drive to my sons new 125.
If you read about it will make much more torque.
F1 moto, the also have a special spring. Have you seen that ?
I haven´t seen/read any review.
Idk is the torque drive will really add torque but theoretically it being lighter weight it should rev quicker. I was only looking at the clutch pack not the full clutch as the stock basket and hub are pretty solid.
Here is the maps my unit has. I currently use 4 or 6 personally depending on the track.
Looking forward to the 2022 season, I just renewed my membership an hour ago.
Here all the bearings in the hybrid ceramic kit
Koyo 6206 C3
Koyo 6305
Koyo 6205 C3 90-14 02
Koyo 6004 C3
Koyo 16003 (x2)
Koyo 626-2r2
Nsk 16002
They all came from worldwide bearings so not in standard box’s.
Edit: Can confirm that is the ball bearing version for the crank.
Pit Row
I’m shocked 😳
Thought they produced from scratch
Purchased an MX-Tech A48R kit from a vital member for cheap. I was planning to eventually go with a lucky kit later in the year but if I end up liking this setup then no need. Reviews are scarce but some people mention better front end feel so thats honestly what I’ve been missing. Though my cheap A$$ tires don’t help lol.
New foot pegs came in from Over seas. Stainless Raptor look a likes. I will say the welds aren’t near as pretty as raptors and ect but they feel solid and many people have said great things about them. They actually only weigh 10 grams more than stock. So that’s a bonus for me.
Got some of the anodized parts initially stripped. Most of the left over anodizing comes off easily with a brush but I don’t have any that aren’t worn out. Next up is to clean them up then trying to decide on the finish.
So the build will actually have no orange on it so that’s the reason for stripping. Part of me just wants to cerakote black because it’s cheap and I don’t have to do any work.
Other part of me wants to get anodizing supplies and anodize them black or a mix of build colors.
Some parts I plan to polish and clear coat.
Today I’m finishing stripping and starting polishing.
Also installing the ceramic hybrid bearings in the engine. I need to buy a few replacement non ceramic bearing that are odd sizes. But after that it will be time to re install all the internals.
This is post red scotch brite pad. Then coarse compound and then the medium. Going to go back on a few pieces and then hit it with the final gloss. I was going to clear coat but decided to just maintain with mothers mag/aluminum polish and graphene coating.
Up close you’ll still see the flaws but for me that’s fine. If I was building this bike for someone else I’d spend a metric ton more time on the polishing to get all of the defects out that I could then it would have much more of a mirror to it. But for me if it looks good from 5 feet away that’s all I care.
Also got the new engine bearings installed minus the water pump ones. Those are on the outer part of the case so I wanted the others seated first and the cases cooled back down. Heated them in the oven at 355 for 10-20 minutes per the manual and the old ones fell right out with the new ones sliding right in.
I’ll get the last 2 in today. Picking up aluminum brightener to get all the stained removed from the cases and the rest of the aluminum. Then final engine assembly.
Anyways otherwise all went well.
Also picked up a nitrogen tank to use with my shock fill kit. Hopefully soon pickup a vacuum bleed setup as well.
Your build is just killer to track and I agree about Cody.
He does some great work and is very easy to work with.
So far I am planning on all the Nationals but Fernly.
Hopefully DT1 is up and running again soon.
DT1 was hoping this weekend but we will see. Hopefully by the 22nd that’s when I should be up and running by.
Engine is all dialed in and in the frame finally. Got the Moto hose in frame y hose installed it was a bit of a struggle but made it happen.
Got the shock rebuilt, revalved, and resprung. Also installed a MX-Tech tank res to get rid of my FC bladder conversion.
Also rebuilt and revalved the forks along with the MX-Tech A48-R air chamber I got off of a member here for a good deal. Looking forward to trying it out and I was able to keep my original chamber in tact.
Got the Ti linkage bolts, triple clamp bolts, engine bolts installed.
Waiting on a package from Spec bolt with a nickel works kit for all of the misc bolts throughout the bike to give it that factory look. Also planning to eventually get a aftermarket clutch cover. Otherwise on Friday the bike will be finished new tires plastics graphics seat and cover. Going to be a busy day in order to ride on Saturday.
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