Luxon MX Motocross Action Mag FC350 Build (Complete)

Luxon MX
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6/27/2021 1:29pm Edited Date/Time 6/7/2023 11:51am

We've had this build going for a while, I just haven't had a chance to get a post going yet, but here we go!

First of all, the 150SX build is still happening, it's just been a little slower than I'd hoped. This build will go a lot faster as we're not going nearly as in-depth with it, but still doing some really cool stuff. This bike will be our primary development bike for the Austrian brands products. And the old Husky is wearing out, so it's time for a freshie!

JMC Motorsports (https://www.jmc-motorsports.com/) hooked us up with a great deal on a new 2021 Husky FC450 late last year, which was pretty awesome of them during a time when bikes were impossible to find or absurdly expensive.

We took delivery of the bike and started stripping it down:



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Luxon MX
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6/27/2021 1:42pm
No big plans for motor work, really. Had I wanted more power, I'd just buy a 450! The 350 is perfect for the Vet pro practice rider who occasionally gets talked into racing, e.g., me, and I don't see a need for more power. But I do see a need for weight reduction and more manageable power, without a compromise in reliability. So we'll be making some changes (bolt-ons) to make that happen.

So, this is pretty much the final motor package:




The keen eye might see some titanium bolts in there. Motostuff has awesome bolt kits; you just pick your bike and the area you want bolts, and they have everything sorted out for you already. This is the "Titanium Engine Fastener Kit, KTM-HUSKY 250F-350F 2016-2020 (39 bolts)". We lost a little weight, but arguably more importantly, everything just looks way nicer without those zinc coated stock bolts. Just be sure to use plenty of anti-seize (we use Loctite C5a) and use a torque wrench to tighten to the appropriate torque (adjusting for the lubricity of the anti-seize and the titanium, it's about 40% LESS torque than what's in the manual).



Chippy
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6/27/2021 9:05pm
Those coated bolts do look really nice.
How do you know the general amount of torque adjustment to account for because of the diff. lubricity?
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Luxon MX
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6/28/2021 8:11am
Chippy wrote:
Those coated bolts do look really nice.
How do you know the general amount of torque adjustment to account for because of the diff. lubricity?
Loctite publishes their friction coefficient data:
http://tds.henkel.com/tds5/Studio/ShowPDF/243%20NEW-EN?pid=LB%208008&fo…

Combine that with our spreadsheet to calculate torque/tension (available here):
https://www.luxonmx.com/resources.html

And verify with some internal testing, and it comes in at about 40% reduction in torque for the same bolt tension.
Mayo513
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6/28/2021 9:10am
Can't wait to watch this! Any chance you will be building/replacing the oil idler pump gear on this motor? Did they update it for the newest models? The 16-18's and maybe more had a nylon/plastic gear that would warp and toast your head. They released an updated gear that is an upgrade of the same material.
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The Shop

Luxon MX
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6/28/2021 9:55am
Mayo513 wrote:
Can't wait to watch this! Any chance you will be building/replacing the oil idler pump gear on this motor? Did they update it for the newest...
Can't wait to watch this! Any chance you will be building/replacing the oil idler pump gear on this motor? Did they update it for the newest models? The 16-18's and maybe more had a nylon/plastic gear that would warp and toast your head. They released an updated gear that is an upgrade of the same material.
The gear issue was fixed on the 2020 models, so good to go here. It's still plastic, but I actually prefer plastic for something like this. It doesn't need to be crazy strong, it has less friction than a steel or aluminum gear, and it's lighter.

Plastic is an awesome material when used appropriately. There are lots of spots on a motorcycle that work out fine for plastic. Brake and clutch master cylinder covers are a good example. You can replace them with anodized aluminum for some bling, but they'll be heavier and offer no performance advantage.
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Rickyisms
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6/28/2021 11:44am
Every time Luxon posts I feel like I'm in a college course. Love learning this stuff.
Luxon MX
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7/3/2021 10:42am
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we will be running (more on that later). So I whipped up some HPSD spuds and welded one on to the frame:


Here's the design in CAD (SolidWorks). It's pretty basic, just wanted function without adding a bunch of weight and keep it relatively easy to manufacture:



The first setup to make this is done on the CNC lathe. The outer profile, M7 drill and threading is done here, then it's parted off to the final length (second photo is right before the part off):





The back side is just drilled out for weight. No point in setting up the CNC for that, so I just knocked it out on the manual lathe:



Then on to the CNC mill to cut in a big circular profile so it mates up to the frame nicely:



And finally, the finished parts:

Luxon MX
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7/3/2021 10:46am
I used an older set of clamps to position things correctly with a simple jig of the right length for the damper (92mm between centers of the holes). It's tack welded here, the jig is removed, and then fully welded.




spimx
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7/5/2021 1:42pm
Why do you need anti seize with ti bolts? Isn't there even less interaction than with stainless bolts and aluminum cases
Luxon MX
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7/5/2021 1:56pm
spimx wrote:
Why do you need anti seize with ti bolts? Isn't there even less interaction than with stainless bolts and aluminum cases
Here are a couple links that explain it pretty well.

Galvanic corrosion is one issue with titanium on aluminum:
https://feoinc.com/learning-center/understanding-preventing-galvanic-co…

Typically, though, the bigger issue is galling:
https://www.boltdepot.com/fastener-information/materials-and-grades/thr…
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Solidkm
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7/10/2021 11:37am
Luxon MX wrote:
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we...
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we will be running (more on that later). So I whipped up some HPSD spuds and welded one on to the frame:


Here's the design in CAD (SolidWorks). It's pretty basic, just wanted function without adding a bunch of weight and keep it relatively easy to manufacture:



The first setup to make this is done on the CNC lathe. The outer profile, M7 drill and threading is done here, then it's parted off to the final length (second photo is right before the part off):





The back side is just drilled out for weight. No point in setting up the CNC for that, so I just knocked it out on the manual lathe:



Then on to the CNC mill to cut in a big circular profile so it mates up to the frame nicely:



And finally, the finished parts:

Do you/Will you sell these?
DJV804
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7/10/2021 2:43pm
Luxon MX wrote:
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we...
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we will be running (more on that later). So I whipped up some HPSD spuds and welded one on to the frame:


Here's the design in CAD (SolidWorks). It's pretty basic, just wanted function without adding a bunch of weight and keep it relatively easy to manufacture:



The first setup to make this is done on the CNC lathe. The outer profile, M7 drill and threading is done here, then it's parted off to the final length (second photo is right before the part off):





The back side is just drilled out for weight. No point in setting up the CNC for that, so I just knocked it out on the manual lathe:



Then on to the CNC mill to cut in a big circular profile so it mates up to the frame nicely:



And finally, the finished parts:

Solidkm wrote:
Do you/Will you sell these?
X2 on this question
Bruce372
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7/12/2021 8:25pm
Quick Q? Billy,

For the amount of aluminum you buy, what % goes to product and what goes to recycling? Presumably big manufacturers employ computer models to minimize whatgoes to the melter.?
Bruce372
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And I must be the only person on the planet that likes ktm torq bolts lol. And the ktm beam counters haha.... so much easier to work on the bike I've found. But definitely don't look nice like titanium

My favorite tool


1
Luxon MX
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7/13/2021 7:33am
Luxon MX wrote:
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we...
We're not planning on running the Honda damper on this build, but I wanted to have the option for testing and comparisons to the damper we will be running (more on that later). So I whipped up some HPSD spuds and welded one on to the frame:


Here's the design in CAD (SolidWorks). It's pretty basic, just wanted function without adding a bunch of weight and keep it relatively easy to manufacture:



The first setup to make this is done on the CNC lathe. The outer profile, M7 drill and threading is done here, then it's parted off to the final length (second photo is right before the part off):





The back side is just drilled out for weight. No point in setting up the CNC for that, so I just knocked it out on the manual lathe:



Then on to the CNC mill to cut in a big circular profile so it mates up to the frame nicely:



And finally, the finished parts:

Solidkm wrote:
Do you/Will you sell these?
DJV804 wrote:
X2 on this question
5
Luxon MX
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7/13/2021 7:54am
Bruce372 wrote:
Quick Q? Billy, For the amount of aluminum you buy, what % goes to product and what goes to recycling? Presumably big manufacturers employ computer models...
Quick Q? Billy,

For the amount of aluminum you buy, what % goes to product and what goes to recycling? Presumably big manufacturers employ computer models to minimize whatgoes to the melter.?
Hey Bruce,

It depends on the product. Our triple clamps only have about 14% of the material left when we're done. The other 86% turns into chips:



We usually order material in quantities of about 2,000 lbs. to get a good price break, which makes for a lot of chips! There's only so much we can do about that. The raw stock comes in 12' bars and in nominal inch sizes for width and thickness, typically half inch increments in the triple clamp sizes (so 2.0" x 3.5" x 12' for example). There's scrap in the cut length as your parts don't usually add up to 12' when all is cut up. That creates a shelf full of remnants that we use for smaller one-off parts or fixtures.

There's also scrap in the thickness and width. You have to buy material that's a little bigger than your end part, plus a little bit to hold on to in the mill vice. We don't do nearly enough quantity to justify it, but we could order custom extrusions to reduce the thickness to the minimum. We design the part to match nominal stock sizes where it makes sense and we're not compromising on the design otherwise. But usually we just design things how they should be, then size the raw stock to fit. It wastes some time in cutting away scrap, and some money in chips, but makes for a better part.

All the aluminum chips are collected and recycled. It gets us some money back (about 15% of the original cost), which is nice. Here I am stomping on the pile of chips in the bin trying to make more room:


Luxon MX
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7/13/2021 7:57am
Bruce372 wrote:
And I must be the only person on the planet that likes ktm torq bolts lol. And the ktm beam counters haha.... so much easier to...
And I must be the only person on the planet that likes ktm torq bolts lol. And the ktm beam counters haha.... so much easier to work on the bike I've found. But definitely don't look nice like titanium

My favorite tool


I'm a big fan of the torx interface too. And of Wiha drivers, that's what we use here! Of all the internal driving fasteners (allen, phillips, etc.), Torx is the clear winner. It's just not often that you find titanium screws with Torx heads, so we're left with hex heads.
5
Bruce372
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7/13/2021 8:26am
Bruce372 wrote:
Quick Q? Billy, For the amount of aluminum you buy, what % goes to product and what goes to recycling? Presumably big manufacturers employ computer models...
Quick Q? Billy,

For the amount of aluminum you buy, what % goes to product and what goes to recycling? Presumably big manufacturers employ computer models to minimize whatgoes to the melter.?
Luxon MX wrote:
Hey Bruce, It depends on the product. Our triple clamps only have about 14% of the material left when we're done. The other 86% turns into...
Hey Bruce,

It depends on the product. Our triple clamps only have about 14% of the material left when we're done. The other 86% turns into chips:



We usually order material in quantities of about 2,000 lbs. to get a good price break, which makes for a lot of chips! There's only so much we can do about that. The raw stock comes in 12' bars and in nominal inch sizes for width and thickness, typically half inch increments in the triple clamp sizes (so 2.0" x 3.5" x 12' for example). There's scrap in the cut length as your parts don't usually add up to 12' when all is cut up. That creates a shelf full of remnants that we use for smaller one-off parts or fixtures.

There's also scrap in the thickness and width. You have to buy material that's a little bigger than your end part, plus a little bit to hold on to in the mill vice. We don't do nearly enough quantity to justify it, but we could order custom extrusions to reduce the thickness to the minimum. We design the part to match nominal stock sizes where it makes sense and we're not compromising on the design otherwise. But usually we just design things how they should be, then size the raw stock to fit. It wastes some time in cutting away scrap, and some money in chips, but makes for a better part.

All the aluminum chips are collected and recycled. It gets us some money back (about 15% of the original cost), which is nice. Here I am stomping on the pile of chips in the bin trying to make more room:


Wow, that's really interesting, and with 86% of material removed, that must correlate with a lot of machine time.

Really makes me wonder about the cost difference between for example a cast clamp vs a machined one. Although, I can imagine a cast part using less raw material, the casting process also uses additional energy resources.
Bruce372
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7/13/2021 8:33am
Bruce372 wrote:
And I must be the only person on the planet that likes ktm torq bolts lol. And the ktm beam counters haha.... so much easier to...
And I must be the only person on the planet that likes ktm torq bolts lol. And the ktm beam counters haha.... so much easier to work on the bike I've found. But definitely don't look nice like titanium

My favorite tool


Luxon MX wrote:
I'm a big fan of the torx interface too. And of Wiha drivers, that's what we use here! Of all the internal driving fasteners (allen, phillips...
I'm a big fan of the torx interface too. And of Wiha drivers, that's what we use here! Of all the internal driving fasteners (allen, phillips, etc.), Torx is the clear winner. It's just not often that you find titanium screws with Torx heads, so we're left with hex heads.
Ok, more questions hahaha...

People don't like the ktm bolts because they are galvanized I think ? and don't look nice compared to the shiny bolts that come on Japanese bikes.

Does anyone know why ktm does it this way?
Luxon MX
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7/13/2021 10:30am
Bruce372 wrote:
Wow, that's really interesting, and with 86% of material removed, that must correlate with a lot of machine time. Really makes me wonder about the cost...
Wow, that's really interesting, and with 86% of material removed, that must correlate with a lot of machine time.

Really makes me wonder about the cost difference between for example a cast clamp vs a machined one. Although, I can imagine a cast part using less raw material, the casting process also uses additional energy resources.
Well, kind of. A stock (machined) KTM clamp will have about the same amount of material removed. But our clamps take far longer to machine due to the level of detail and the large amount of 3D surfacing. The stock stuff is super easy to machine, typically with no 3D surfacing. It's flat across the top, and has milled out pockets on the bottom, usually with large radii in the corners so they can use a single end mill at high speed. Our stuff is far more optimized, so there are lots of 3D surfaces on all sides of the part, lots of pockets with varying and small radii (so smaller mills are required), they're split on the bottom, etc.

For example, a stock KTM bottom clamp probably requires 11 tools to machine in about 20 minutes of machine time. Ours require 27 tools and about 70 minutes of machine time. It's obvious why when you look at it, they're a lot more complex:




Regarding casting, the stock clamps on most bikes are actually forged. Sometimes the upper clamp is cast, but the lower is almost always forged. With either technique, you have to clean up the resulting casting/forging on a CNC machine to add holes and threads, clean up the fork tube clamp area, etc. Despite that, the process is a lot faster and less expensive than machining the entire clamp, which is why you see most OEMs doing it that way.

Ideally we'd forge our clamps. But we just don't have the volume to justify the extreme tooling costs to do that. And machining is very forgiving to design changes and updates.
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Luxon MX
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7/13/2021 10:36am
Bruce372 wrote:
Ok, more questions hahaha... People don't like the ktm bolts because they are galvanized I think ? and don't look nice compared to the shiny bolts...
Ok, more questions hahaha...

People don't like the ktm bolts because they are galvanized I think ? and don't look nice compared to the shiny bolts that come on Japanese bikes.

Does anyone know why ktm does it this way?
I'm pretty sure it has something to do with European or Austrian environmental limitations on the coatings. They have to use the coating they're using as it passes the regulations. Most everyone uses zinc plating, which looks a lot nicer.
5
DJV804
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7/13/2021 12:37pm
Luxon MX wrote:
Oh, and if you haven't already, give a listen to the podcast I did with Klinger a few weeks back. I drone on for 40 minutes...
Oh, and if you haven't already, give a listen to the podcast I did with Klinger a few weeks back. I drone on for 40 minutes about a lot of this stuff... Laughing

https://www.vitalmx.com/features/The-Inside-Line-Podcast-Tech-Edition-T…
One of the best and most interesting podcasts I’ve ever listened to. Thanks for doing that!
4
Luxon MX
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7/23/2021 5:27pm
OK, so we welded on that HPSD mount last post, but as mentioned, it’s not the damper we’re planning on running; I just wanted the option for some testing in the future. We’ve heard great things about the Precision Racing Products damper system, and it looks like a quality piece, so we’re going with it! This mounts to the handlebars directly, so no oddball bar mounts are required and it’s much more compact and lighter than the other dampers out there:

https://precision-rp.com/Parabolic-1-18-bar-complete-KTM-Husqvarna_p_31…






There are a couple issues with this damper for our bike, though:

1) It works with 1 1/8” bars, but I’m planning on running the Renthal FB36 bars. So we’re going to make some new parts to make that happen.

2) It doesn’t work with our bar mounts as it needs to clamp the bars. Our mounts are solid across the bottom, so we’re going to make something special for that too.

3) I don’t like bolt-on parts that can otherwise be welded on.

So first thing is to replace the frame clamp with a weld on part. This will be lighter, won’t ever come loose, increases clearance for everything else (clamps, knees, etc.), and looks a lot better.

I modeled up the relevant parts of the frame, steering bearings, etc. and designed a lower damper mount to replace the bolt-on version:




Here’s the CNC programming interface with the toolpaths shown:




And the finished part:



This is steel since we have to weld it to the steel frame, but only adds ~40g to the weight of the bike as I was rather aggressive at removing material, and arguably spent more time on this than I should have!
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Luxon MX
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7/23/2021 5:30pm
Now to weld it on. It’s not a simple part to hold in the right position, so I whipped up a jig to hold it in place on the CNC machine:




This really makes it easy to align in the right spot and straight along the centerline of the frame:




I just tack welded it on while it was jigged up, removed the jig, and finished the welding:




Good to go now and the frame is off to powder coat!





Luxon MX
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8/6/2021 6:50am
Just got the frame back from sandblasting and powdercoat. I went with "black magic" for the color, which is just black with a little metallic effect. Black goes with everything and looks a lot better than the dark blue it comes with stock!




I had whipped up a coupe pieces on the lathe to block the powdercoat from the steering bearings and also loaded the frame up with old fasteners to make life easier on the powdercoat guys (and ensure masking was done right), so that made for an easy prep of the frame before putting things back together. All that was left was to hit the engine, subframe, and electrical mount areas with a Dremel for conductivity.




First parts to go on are the pegs so I can zip-tie the frame to the stand for stability. Motostuff sells these titanium Pro Pegs (https://motostuff.com/products/pro-pegs-titanium-footpegs) that we went with. I've used these same pegs on our 150 build and really like them. They're very similar to the Raptor pegs in size, weight, design, and quality, but a little cheaper.




And here's the damper post bolted up to its new home on the frame:




This is the exciting part as everything starts coming back together!

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