YZ450f KMS turbo build

Swagger · Feb 18, 2019

Hi guys, pretty new here.
Anyways, I acquired a second hand KMS turbo kit for my 2010 YZ450F, and am looking forward to getting it installed. I have never done a turbo kit or any turbo work, but am pretty good when it comes to rebuilding a dirtbike motor and other mechanical stuff.
First thing I need, is a install manual. Seems like KMS doesnt make these kits anymore, so if anyone knows where I could get a manual, that would be nice.
Second thing, is a link to a write up on the basics of doing turbo conversions on these bikes.
The kit came with a lockout clutch. Is there an option for a rekluse or rekluse type of clutch that will handle the power?
Kit also came with a low compression piston. What you recommend- low comp piston and pump gas or hi comp piston with a race fuel mix?

Thanks in advance

swedenturbo · Feb 18, 2019

I built my own turbo kit so I cant help you with your specific KMS kit.
I have tested to run with Rekluse but it couldnt handle the power/torque. I use double beleville springs on my KTM500 turbo.
I think a clutch lockout is a nice idea as you can run standard springs and the lockout increase clutch pressure the more you rev.
Easier clutch actuation than using heavier springs....

Have tested both standard 11,8:1 compression and a 10:1 custom made low comp piston, both on 102 MON octane race fuel.
Boosted 11,6 psi with the 10:1 but unfortunalely with a big end conrod failure.
Currently boosting 7,25 psi with standard 11,8:1 standard piston.
I highly recommend you go for that setup. It pulls really hard and with great reliability 93 hp at rear wheel.
Use good race fuel to prevent knock.
Try to stay off the revlimiter as I think overreving kills most dirtbike turbo engines ;-)

wwillf01 · Feb 18, 2019

Swagger said:
Hi guys, pretty new here.

Anyways, I acquired a second hand KMS turbo kit for my 2010 YZ450F, and am looking forward to getting it installed. I have never done a turbo kit or any turbo work, but am pretty good when it comes to rebuilding a dirtbike motor and other mechanical stuff.

First thing I need, is a install manual. Seems like KMS doesnt make these kits anymore, so if anyone knows where I could get a manual, that would be nice.

Second thing, is a link to a write up on the basics of doing turbo conversions on these bikes.

The kit came with a lockout clutch. Is there an option for a rekluse or rekluse type of clutch that will handle the power?

Kit also came with a low compression piston. What you recommend- low comp piston and pump gas or hi comp piston with a race fuel mix?

Thanks in advance

There was never a manual from kms that was one of the problems... Do not use a rekluse it will be a nightmare with the turbo which the mapping will rely heavily on a healthy none slipping clutch. Make sure you have 100 octane if you are running 10 psi (I am sure the map is built around this... Use a new afr sensor.... I recommend turning off auto-tune once you get to your riding area and it is running good...

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powdermuncher · Feb 18, 2019

I have never done a turbo kit or any turbo work, but am pretty good when it comes to rebuilding a dirtbike motor and other mechanical stuff.
[/QUOTE]

That is a really good starting point you will rely on that skill a fair bit if you put much time on any turbo snow bike. They go from no power to hitting the rev limiter very quickly and nothing good happens there for any engine let alone a turbo single cylinder. Just imagine what happens when you hit the limiter at max boost Ignition cuts out boost drops waste gate closes to maintain boost ignition cuts back in boost spikes instantly before the wast gate has a chance to open up to relieve the overboots -- at that point you spike rpm again and the whole cycle starts again al the while you hope that at least fuelling is somewhere in the ballpark. Good luck on that -- that in a nutshell is your Achilles heel on a turbo snow-bike. I would highly recommend to try one first before you build something that does not live up to your expectations. Just my 2 cents worth.

wwillf01 · Feb 18, 2019

I ran one and honestly I did
not have a problem staying off the rev limiter but I did have an issue with toasting clutches... Also be careful on your bike shifter gears so you don't bend the forks... You just have to ride it like a 2 stroke basically...

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Swagger · Feb 21, 2019

swedenturbo said:
I built my own turbo kit so I cant help you with your specific KMS kit.
I have tested to run with Rekluse but it couldnt handle the power/torque. I use double beleville springs on my KTM500 turbo.
I think a clutch lockout is a nice idea as you can run standard springs and the lockout increase clutch pressure the more you rev.
Easier clutch actuation than using heavier springs....

Have tested both standard 11,8:1 compression and a 10:1 custom made low comp piston, both on 102 MON octane race fuel.
Boosted 11,6 psi with the 10:1 but unfortunalely with a big end conrod failure.
Currently boosting 7,25 psi with standard 11,8:1 standard piston.
I highly recommend you go for that setup. It pulls really hard and with great reliability 93 hp at rear wheel.
Use good race fuel to prevent knock.
Try to stay off the revlimiter as I think overreving kills most dirtbike turbo engines ;-)

Its a good thing then I got it with the lockout clutch

Thanks for the tips on the turbo setup. Ive seen some of threads of your builds and dang bro you got fab skills! Would love to get one of your built tracks to try out!

Seems like the census for the yz450f 12.5:1 comp piston and all stock internals (right? stock crank and all?) is to go around 10psi on 100 octane.
The guy I got the kit from was mixing aviation fuel with pump gas to get 100 octane. Is that the same as race fuel? or does race fuel have more additives that make it better?

Swagger · Feb 21, 2019

wwillf01 said:
There was never a manual from kms that was one of the problems... Do not use a rekluse it will be a nightmare with the turbo which the mapping will rely heavily on a healthy none slipping clutch. Make sure you have 100 octane if you are running 10 psi (I am sure the map is built around this... Use a new afr sensor.... I recommend turning off auto-tune once you get to your riding area and it is running good...

Sent from my Pixel 2 XL using Tapatalk

any other members on here that have used the KMS kit?

Got the lockout clutch

See above post regarding octane question.

Not sure yet what auto tune is, or if I even have that. I havent even opened the box of parts yet lol (I had a friend pick it up for me). Why do you recommend turning it off? dont know what it is, but It sounds like its the computer that makes all the adjustments for elevation and boost and what not?... sounds like something I should leave on during riding...

Swagger · Feb 21, 2019

powdermuncher said:
I have never done a turbo kit or any turbo work, but am pretty good when it comes to rebuilding a dirtbike motor and other mechanical stuff.

That is a really good starting point you will rely on that skill a fair bit if you put much time on any turbo snow bike. They go from no power to hitting the rev limiter very quickly and nothing good happens there for any engine let alone a turbo single cylinder. Just imagine what happens when you hit the limiter at max boost Ignition cuts out boost drops waste gate closes to maintain boost ignition cuts back in boost spikes instantly before the wast gate has a chance to open up to relieve the overboots -- at that point you spike rpm again and the whole cycle starts again al the while you hope that at least fuelling is somewhere in the ballpark. Good luck on that -- that in a nutshell is your Achilles heel on a turbo snow-bike. I would highly recommend to try one first before you build something that does not live up to your expectations. Just my 2 cents worth.[/QUOTE]

The revlimiter thing might be an issue for me. If its a steep hill I just grin, WOT, shoot straight up :face-icon-small-hap I dont even hear the engine...lol.
Im gonna have to change my habit lol. Is it all that bad though if I
hit it momentarily and then either shift or let off a little?
Dont know where I could find one to try first, but if your gonna be disappointed in a turbo snowbike then you shouldnt be out on a snowbike at all :face-icon-small-win

Swagger · Feb 21, 2019

wwillf01 said:
I ran one and honestly I did
not have a problem staying off the rev limiter but I did have an issue with toasting clutches... Also be careful on your bike shifter gears so you don't bend the forks... You just have to ride it like a 2 stroke basically...

Sent from my Pixel 2 XL using Tapatalk

Yeah Im gonna have to get out of my powershifting habit to lol.

On a side note about shifting, I dont know what you all wear when you go riding, snowboarding boots or snowmobiling boots, but I found those to be really difficult to shift with, especially on snowbikes when your shifts have to be really fast to keep the track from losing momentum. And thats coming from someone who has never used motocross boots in the dirt, I always just wear regular work/hiking boots (I dont race, just casual trails and enduro). Anyways, I wear the same boots on the snowbike (insulated though, my dirt boots are un-insulated) and wear gators to keep the snow out. works amazing, shifting is super easy, and walking over to help out your stuck sledding buddies is also easier :face-icon-small-ton

wwillf01 · Feb 21, 2019

Swagger said:
any other members on here that have used the KMS kit?

Got the lockout clutch

See above post regarding octane question.

Not sure yet what auto tune is, or if I even have that. I havent even opened the box of parts yet lol (I had a friend pick it up for me). Why do you recommend turning it off? dont know what it is, but It sounds like its the computer that makes all the adjustments for elevation and boost and what not?... sounds like something I should leave on during riding...

You would have to see what was sent... I assume it is managed by a power commander ECU. It should have a box that says auto-tune on it. Again it works ok for the initial set up but only can do so much to the fueling tables depending how it was left.... If you have limited experience I would install and see how it runs... If you have issues the best way to get it dialed initially is via a Dyno ... Hopefully the previous owner got the map dialed... I went through 8 revisions .... Fueling wise I used a low comp piston so I was just using premium fuel..

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Swagger · Feb 21, 2019

wwillf01 said:
... Use a new afr sensor....

OEM? or is there a specific one for turbo setups?

Swagger · Feb 21, 2019

wwillf01 said:
You would have to see what was sent... I assume it is managed by a power commander ECU. It should have a box that says auto-tune on it. Again it works ok for the initial set up but only can do so much to the fueling tables depending how it was left.... If you have limited experience I would install and see how it runs... If you have issues the best way to get it dialed initially is via a Dyno ... Hopefully the previous owner got the map dialed... I went through 8 revisions .... Fueling wise I used a low comp piston so I was just using premium fuel..

Asked the guy who sold it to me, he says he didnt have any maps changed on it or anything, the autotune takes care of it all.
That kinda confuses me know cuz earlier someone said to unplug the autotune once on the mountian....?

wwillf01 · Feb 21, 2019

Mine was on a KTM maybe the yamaha is different. But as soon as your clutch start slipping or something in your engine changes and it starts auto-tuning for it that causes problems. I would definitely install it and run it and see what happens just watch your gauges.

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eric82930 · Feb 21, 2019

I didn't see it mentioned anywhere but what altitude will it be run? Sea level has 5psi more atmosphere than we have in the mountains. You can run more compression at high altitude on pump gas because the air starts out 5psi less than sea level.

Swagger · Feb 21, 2019

wwillf01 said:
Mine was on a KTM maybe the yamaha is different. But as soon as your clutch start slipping or something in your engine changes and it starts auto-tuning for it that causes problems. I would definitely install it and run it and see what happens just watch your gauges.

What should I be looking for on the gauges? what are the normal parameters and abnormal readings?

Swagger · Feb 21, 2019

eric82930 said:
I didn't see it mentioned anywhere but what altitude will it be run? Sea level has 5psi more atmosphere than we have in the mountains. You can run more compression at high altitude on pump gas because the air starts out 5psi less than sea level.

Riding is going to be from 3-6k feet elevation. Im guessing most of the numbers being given here for boost and compression are going to be for elevation in that ballpark, right? Unless you live in northern alaska, dont know who rides a snowbike at sea level.

Swagger · Feb 21, 2019

Also, from what I'm reading in other places, looks like I will need head studs that can handle all that boost. Where can I get those? as my used kit came without them....?

Sheetmetalfab · Feb 21, 2019

Swagger said:
Also, from what I'm reading in other places, looks like I will need head studs that can handle all that boost. Where can I get those? as my used kit came without them....?

ARP.

Swagger · Feb 22, 2019

ARP doesnt have yamaha studs that I could search for using the make/model search. But Im pretty sure they have my needed bolt size in stock that is the same size used by another car or whatever.
problem is I searched online extensively, and could not find the size specs for the yz450.
Anyone know the size specs of the 450 head bolts??...

Sheetmetalfab · Feb 22, 2019

Swagger said:
ARP doesnt have yamaha studs that I could search for using the make/model search. But Im pretty sure they have my needed bolt size in stock that is the same size used by another car or whatever.
problem is I searched online extensively, and could not find the size specs for the yz450.
Anyone know the size specs of the 450 head bolts??...

Usually the dealer can give you the specs on a bolt/stud.

(Or just order one and measure it. )

YZ450f KMS turbo build

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