KTM 450 SXF KMS Turbo Build start to finish

KMS · Oct 15, 2014

Here is the build:

We hunted down a used 2014 KTM 450 SXF that was used for local mx racing. Overall the bike was in ok shape, however the bike only made 43hp on the dyno, about 5hp shy from stock. Clearly this bike is tired…but we’re going to fix that.

Specs for the build:

KMS Front Mount Turbo System
KMS 102mm big bore kit @10:1 compression
And many step by step upgrades.

We want to push this new big bore very hard to stress test the capacity of the cylinder structure…so, the first upgrade that was selected was Boring the Throttle Body.

We disassembled and precision bored this throttle body to a +2 and undercut the shaft for additional flow. This will provide more airflow to the head and increase horsepower through efficiency. The new throttle plate is also precision cut with relief tapers to ensure steady idle and smooth low speed operation.

KMS · Oct 16, 2014

We started off the day with a leak test, measuring at 4% (very good). We knew to keep our eyes peeled during the top end teardown (remember the bike was 5hp shy of stock). Valves good, seats good, carbon on piston (expected), piston to cylinder clearance ok, cam timing good but cam has rolled back a little….
This is important to note. If you ever find yourself “between teeth” on cam timing, your cam chain is stretched. This will actually roll the lobe centers and cause subtle performance loss. So we added a new cam chain to the parts list.

Head is now off to be cnc ported….But look what showed up. The 102mm cylinder.

This thing is huge compared to the oe piston.

We are now going to prep this cylinder for the turbo install. This requires additional machining that will strengthen the head gasket surface and lock down the head gasket.

rottinjonny · Oct 16, 2014

Very cool! Do you plan to break in this engine and do a couple dyno pulls before the turbo install? I'd be curious as to the hp and torque numbers on the big bore itself. Numbers may be low due to lowered compression?

KMS · Oct 16, 2014

The "pre turbo-post big bore" dyno pull was not on the table because the information would be for a configuration that nobody would ever install (a na big bore with low compression)....However, if you want to see this, just let us know and we will do it.

Thanks for the question!

Curt_T · Oct 16, 2014

KMS said:
The "pre turbo-post big bore" dyno pull was not on the table because the information would be for a configuration that nobody would ever install (a na big bore with low compression)....However, if you want to see this, just let us know and we will do it.

Thanks for the question!

Your right on the low side but of all the motors I've built compression helped rev faster and only ever picked up small gains in hp. I've never built a dirt bike motor but can't be to much differnt. But I would also like to see this on a dyno for the guys that can't go all out in one year. Such as motor build this year and turbo next year.

KMS · Oct 16, 2014

The Turbo is here! For this build, we decided to upgrade to the Ball Bearing GT2252.

This Ball Bearing turbo will build target boost very fast (usually in ½ the time of the journal bearing counterpart). This will give the bike very large area horsepower, huge torque, and offer a high boost potential.

From this point, this turbo will be stripped down and prepped for system. The turbo is shaved and clocked specifically for the KTM 450 SXF, however the most important thing that happens is the turbine housing is sent off to be Ceramic Coated Black and here is why:

This turbine housing has only seen maybe 15-20 dyno runs and has lived it's entire life in Phoenix. If you think this thing looks nasty, imagine what one would look like after 1 season in the snow! Furthermore, the Ceramic Coating will help keep the heat where it belongs (inside the turbine). Every system we build gets this service because performance and looks do go hand in hand.

mrsnaglepuss · Oct 18, 2014

Thanks for posting this build excellent info and workmanship.

KMS · Oct 18, 2014

You're welcome...I do find it interesting that I am one of few turbo system builders that will display how their stuff works publicly. There is this belief that if you keep your stuff "lock and key" and very secret, you are protecting your intellectual property (we worked very hard on this and we don't want you to just copy it).

The reality is far from that. The real fear is that another builder could make one better than yours. They start with what you make and a couple changes later, they now are making a better system than yours. If there is a better way to build a turbo system, I get excited and test the better way immediately! My goal is simple, offer the highest amount of power with the least amount of boost (maximum efficiency). The only way to get there is...Test Everything.

The biggest problem with a "top secret" approach is, as a builder, you really do shoot yourself in the foot. Here is why: customer support! If you are the only one on the face of the earth that fully understands how your stuff works, guess what happens when a customer has a problem....You become their only source of support. If my customer has a problem, I want it resolved NOW. If I cannot get it resolved on the phone, I need others who can help him in person (ie a local shop). If I lock the information down, how could I ever expect any experienced mechanic to help the customer. This is where laying out entire system designs become not only worth it to me, but a must have because most forced induction information is obscure at best.

Bottom line is this: After many years of boosting, Turbo System builders who "hide" their stuff not only stunt their own technological growth, they also do a real disservice to their customers.

PS. As you see this build progress and you have an idea, I would love to hear it. Lets make this fun!

summitboy · Oct 18, 2014

Curious what kind of weight a kit adds to a bike ?

cr500afx · Oct 18, 2014

summitboy said:
Curious what kind of weight a kit adds to a bike ?

24 pounds. KMS lists the weight of their system along with a lot of other info on their website. https://www.kmsperformance.com/shop/custom.aspx?recid=3

KMS · Oct 18, 2014

I list this on my website right here:

https://www.kmsperformance.com/shop/custom.aspx?recid=3

But here is the breakdown:

For the KTM 450 Rear Mount

ADDED WEIGHT TO BIKE
TURBO 12 LBS
PIPES AND COOLER 12 LBS
Total 24 LBS

For the KTM 450 Front mount

ADDED WEIGHT TO BIKE
TURBO 12 LBS
PIPES AND COOLER 16 LBS
Total 28 LBS

Thanks for the great question, we spent a ton of time over the summer to make these things as light as possible without compromising the structural integrity. Our customers wanted it and we listened.

mrsnaglepuss · Oct 19, 2014

I love turbos......but maybe your turbo is better than the power plants your putting them on.

There is no question that adding a turbo like this can probably double stock h.p. Numbers on most thumpers For a minimal amount of weight, equals best power to Wt. ratio. You do need however to start with a freshened or new engine, arp head studs, ported head, bored throttle body, add turbo & plumbing, piping, etc. plus buckets of $$George Washington$$, I'm still stuck with the Queen of England here and her ship is sinking. The big question I am asking is what is the real longevity of these thumpers spooled up and pushing boost and bouncing off the rev limiter all day? Did I mention the clutch and tranny?

Not trying to be negative here just my observations.

cr500afx · Oct 19, 2014

I have a KMS turbo'd CRF450. It's a stock motor and this year will be its 4th season on the snow. This was the first snowbike KMS turbo'd and was new when turbo'd. The turbo doubled the stock HP (dyno'd). It's still going strong, but could probably use a freshen up. Still running same modified Rekluse clutch, with KMS clutch lockout with no issues whatsoever. I think the lockout makes any clutch issues go away with the higher HP builds.
No issues with the tranny, KMS provided a countershaft support which keeps the gears all in line during the high HP pulls.
I think the KTM that KMS is building in this thread is an over the top build with lots of extras to push the upper limit for single cylinder HP.

summitboy · Oct 19, 2014

Curious how many hours that is ? How many days ? I know guys with stock 4 strokes that barely made 5 days with motor issues. Seen a BB chuck a bearing within a season. Talked to turbo guy and said you get a lot of cam and valve wear etc. It will be interesting to see the turbos engine life over the next while since many will go this route. Can't wait for the 200hp bikes to show up lol.

cr500afx · Oct 19, 2014

summitboy said:
Curious how many hours that is ? How many days ? I know guys with stock 4 strokes that barely made 5 days with motor issues. Seen a BB chuck a bearing within a season. Talked to turbo guy and said you get a lot of cam and valve wear etc. It will be interesting to see the turbos engine life over the next while since many will go this route. Can't wait for the 200hp bikes to show up lol.

My CRF450 mentioned above has around 30-40 days on it, say 5 hours a day, so 150-200 hours. It's a dedicated snow bike and has never seen dirt. I'm going to tear down the motor to freshen up this fall and will know more.
Coincidentally, I'm looking for that same bike, 200HP, 121 with 3" paddle, 250#'s weight....

summitboy · Oct 19, 2014

It will be here soon. 100+hp normally aspirated engines will be common. 50lb lighter kits will be here in a couple months lol. Development and tech is being driven which is sweet. I call this stage we are in the RX1 stage ha ha. 121 is for the trail :face-icon-small-sho

mtn-doo · Oct 19, 2014

summitboy said:
121 is for the trail :face-icon-small-

Lol,... Tell Reagan that!

M5- · Oct 20, 2014

I thought he switched to an SX kit?

M5

M5- · Oct 20, 2014

These days I'm more interested in weight reduction than all out power. Having spent the last 9 seasons on a turbo Yami I'm used to lots of weight but I don't really love that part of a turbo sled. My steelie CR500 is a full 30 lbs lighter than my KTM 450 (BB 520) as measured on the scales. Any thoughts of doing 2 stroke turbo system? It would need to be a carb bike.

M5

Lachoneus · Oct 20, 2014

I second that notion!

Have two 2-stroke snowbikes, KTM XC300 and Kawi KX500....thanks.

KTM 450 SXF KMS Turbo Build start to finish

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