I'll call and ask, but I dont think they see anymore info than what I do looking on parts diagrams and stuff... I'll try asking on thumpertalk
YZ450f KMS turbo build
- Thread starter Swagger
- Start date
Have now ridden turbocharged snowbikes for 7 years. Tested different setups on several bikes.
I see that many snowbikers look for high power up to +100 hp.
Have tested this and run with boost up to 0.8 bar and close to 97 rwhp.
The problem is that reliability is deteriorating when you go for such high boost levels. We all want high power and a rideable bike that holds up more than 100 hrs without rebuild, right?
As soon as you go above 0.5 bar, extensive engine modifications will be required and yet it is uncertain whether the reliability is sufficient.
It will require substantial modifications like a custom piston, custom carillo rod and head studs. Expensive modifications literally.
In addition, different bike manufacturers have different bearings of the crankshaft. Most have roller bearings, which I think is a weaker bearing for turbos. KTM 2016- has journal bearing that is much stronger i.e. more suitable for turbocharging.
I’m pretty sure Yamaha is running roller bearing crankshafts ....
From my testing, a stock conrod will not hold up with 0,8 bar. Have looked for a custom Carillo but it wasn’t easy to order and also expensive.
After comparing 0,5 bar and 0,8 bar boost, the driveability is almost equivalent boosting 0.5 bar. Slightly lower peak power but significantly simpler build and with really good reliability. With my current 0,5 bar setup, I run with the engine completely unmodified. Simple assembly and no special parts. Just a reinforced clutch.
I see that many snowbikers are hesitant about turbocharging their dirtbike. I think this is because many who have tested turbocharging have run with too much boost, pinned it to the revlimiter or with a questionable turbo design. Not good for everyday snowbiking.
50% more power is awsome, compared to 80% and a broken engine, right?
I suggest you go for a stock engine and run less boost. From my testing, 0,5 bar looks to be the sweetspot.
I’m running MCX piggyback barometric compensated TCV boost control. This means that more boost is added as you gain altitude meaning that you have the same power at sealevel and 10000 ft. Not sure if KMS have this feature?
Many people think that racefuel is expensive and look for cheaper solutions. Here in Sweden, race fuel is more than twice as expensive as pump gas.
Still, I think it's worth paying the extra cost for race fuel. I run with 102 oct MON, a moderate octane fuel. This fuel is kind to rubber seals/hoses, plastic tanks and the bike can be left fully fueled without problems. In addition, it is storage stable and can be stored for a long time in standard plastic containers. I use this fuel just like any pump gas. Higher octane numbers are more expensive, requiring epying the tank after every ride, cant withstand sunlight (transparent fuel tank) and have a limited shelf life. These fuels are sold in metal containers.
In addition, snowbikes consume about half the amount compared to sleds. Not to mention that the cost of expensive blown belts is eliminated ....
I dont know if 100LL avgas or a mix of pumpfuel works similar to racegas. Maybe, maybe not... Cheaper but maybe not if you grenade the engine due to poor fuel quality?
Never toasted a clutch. Double springs seems to work just fine.
Rekluse was a nightmare, it was slipping most of the time. Nice idea but it doesn’t work with a turbo. Tested different oils. Tried different springs on the expantion ring and heavier weight. Sad to say it but it just does not work with a turbo!
I see that many snowbikers look for high power up to +100 hp.
Have tested this and run with boost up to 0.8 bar and close to 97 rwhp.
The problem is that reliability is deteriorating when you go for such high boost levels. We all want high power and a rideable bike that holds up more than 100 hrs without rebuild, right?
As soon as you go above 0.5 bar, extensive engine modifications will be required and yet it is uncertain whether the reliability is sufficient.
It will require substantial modifications like a custom piston, custom carillo rod and head studs. Expensive modifications literally.
In addition, different bike manufacturers have different bearings of the crankshaft. Most have roller bearings, which I think is a weaker bearing for turbos. KTM 2016- has journal bearing that is much stronger i.e. more suitable for turbocharging.
I’m pretty sure Yamaha is running roller bearing crankshafts ....
From my testing, a stock conrod will not hold up with 0,8 bar. Have looked for a custom Carillo but it wasn’t easy to order and also expensive.
After comparing 0,5 bar and 0,8 bar boost, the driveability is almost equivalent boosting 0.5 bar. Slightly lower peak power but significantly simpler build and with really good reliability. With my current 0,5 bar setup, I run with the engine completely unmodified. Simple assembly and no special parts. Just a reinforced clutch.
I see that many snowbikers are hesitant about turbocharging their dirtbike. I think this is because many who have tested turbocharging have run with too much boost, pinned it to the revlimiter or with a questionable turbo design. Not good for everyday snowbiking.
50% more power is awsome, compared to 80% and a broken engine, right?
I suggest you go for a stock engine and run less boost. From my testing, 0,5 bar looks to be the sweetspot.
I’m running MCX piggyback barometric compensated TCV boost control. This means that more boost is added as you gain altitude meaning that you have the same power at sealevel and 10000 ft. Not sure if KMS have this feature?
Many people think that racefuel is expensive and look for cheaper solutions. Here in Sweden, race fuel is more than twice as expensive as pump gas.
Still, I think it's worth paying the extra cost for race fuel. I run with 102 oct MON, a moderate octane fuel. This fuel is kind to rubber seals/hoses, plastic tanks and the bike can be left fully fueled without problems. In addition, it is storage stable and can be stored for a long time in standard plastic containers. I use this fuel just like any pump gas. Higher octane numbers are more expensive, requiring epying the tank after every ride, cant withstand sunlight (transparent fuel tank) and have a limited shelf life. These fuels are sold in metal containers.
In addition, snowbikes consume about half the amount compared to sleds. Not to mention that the cost of expensive blown belts is eliminated ....
I dont know if 100LL avgas or a mix of pumpfuel works similar to racegas. Maybe, maybe not... Cheaper but maybe not if you grenade the engine due to poor fuel quality?
Never toasted a clutch. Double springs seems to work just fine.
Rekluse was a nightmare, it was slipping most of the time. Nice idea but it doesn’t work with a turbo. Tested different oils. Tried different springs on the expantion ring and heavier weight. Sad to say it but it just does not work with a turbo!
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if your gonna be disappointed in a turbo snowbike then you shouldnt be out on a snowbike at all 
[/QUOTE]
You be disappointed as well when a well set up big bore kicks your but in the trees and any technical riding -- there is a reason the snow bike turbo Idea never really took of.
[/QUOTE]You be disappointed as well when a well set up big bore kicks your but in the trees and any technical riding -- there is a reason the snow bike turbo Idea never really took of.
if your gonna be disappointed in a turbo snowbike then you shouldnt be out on a snowbike at all
You be disappointed as well when a well set up big bore kicks your but in the trees and any technical riding -- there is a reason the snow bike turbo Idea never really took of.[/QUOTE]
Pretty accurate summary. ^^^
You need these camshafts, they are degreed by KMS for that specific bike and turbo system.
https://www.ebay.com/itm/2010-2013-...118976?hash=item3b21adf4c0:g:n9MAAOSwHPNbFyhG
https://www.ebay.com/itm/2010-2013-...118976?hash=item3b21adf4c0:g:n9MAAOSwHPNbFyhG
Thanks a ton for all your wisdom swedenturbo!!
I plan to start putting it all together this weekend. Will post pics.
Well, now you got me a bit disappointed....
But in any way, turbos are cool, I got a good deal on it, and its twice the power of the stock 450 :
I have head studs on order, the cams, LED lights, and other goodies on order. Want to really trick out this setup.
What is the current best front ski to be running?
If it matters, I have a 2012 timbersled 120 track with extenders for a 129 track.
What is the current best front ski to be running?
If it matters, I have a 2012 timbersled 120 track with extenders for a 129 track.
Also, what is the best gearing setup on this turbo bike?
I understand basic gearing, but its always bothered me to know if an increase in the front sprocket size will have the same effect as a decrease in rear sprocket size? I know both will give it a higher top speed, but is there a specific gearing that will give more of wide gear transmission effect? And another setup will make it feel more like a close ratio tranny? Or doesnt matter the only difference will be top speed?
I do need a higher top speed though, as with its current gearing its to slow on the trail, feels like I'm winding out the motor.
I understand basic gearing, but its always bothered me to know if an increase in the front sprocket size will have the same effect as a decrease in rear sprocket size? I know both will give it a higher top speed, but is there a specific gearing that will give more of wide gear transmission effect? And another setup will make it feel more like a close ratio tranny? Or doesnt matter the only difference will be top speed?
I do need a higher top speed though, as with its current gearing its to slow on the trail, feels like I'm winding out the motor.
Yes exactly, your minimum speed in first gear with fully engaged clutch is going to be higher, so you will have a tendency to ride the clutch. Thats kind of what I was asking about in terms of gearing on the bike and within the timbersled itself, that will give more of a KTM type wide gears instead of just changing the top speed.
Wide ratio transmisions seems to work better on turbos.
KTM 500 EXC is a good example of that.
KTM 500 EXC is a good example of that.
Also, to complete this build, what are you guys doing to prevent gas and oil from leaking out when the bike is tipped over? or when you gotta roll it over to get unstuck?
Last time I had a good amount of oil come out of the valve cover breather when I rolled it. Do it a few times and bike will get critically low on oil...
I know theres these for the gas tank https://www.amazon.com/Universal-Breather-Motorcycle-Yamaha-Suzuki/dp/B07GH719WB/
But it seems like they are more prone to getting ripped off when the bike is being rolled and then you have a bigger problem...
For the valve breather, I have the idea to to replace the hose with one that has an inline filter for thin liquids like gas, and locate the filter as close to the valve cover as possible, and then run the hose up instead of down, and place another small filter on the end to keep dirt out. The idea behind it is that when the bike is tipped over the inline filter will pretty much stop any outflow of oil due to its viscosity. When bike is upright and started, the air will still be able to freely flow through the filter, and whatever oil gets forced past due to airflow/pressure will get trapped in the section of tubing that runs upward, and will eventually drain back into the engine. Viable solution? yes? no?
Last time I had a good amount of oil come out of the valve cover breather when I rolled it. Do it a few times and bike will get critically low on oil...
I know theres these for the gas tank https://www.amazon.com/Universal-Breather-Motorcycle-Yamaha-Suzuki/dp/B07GH719WB/
But it seems like they are more prone to getting ripped off when the bike is being rolled and then you have a bigger problem...
For the valve breather, I have the idea to to replace the hose with one that has an inline filter for thin liquids like gas, and locate the filter as close to the valve cover as possible, and then run the hose up instead of down, and place another small filter on the end to keep dirt out. The idea behind it is that when the bike is tipped over the inline filter will pretty much stop any outflow of oil due to its viscosity. When bike is upright and started, the air will still be able to freely flow through the filter, and whatever oil gets forced past due to airflow/pressure will get trapped in the section of tubing that runs upward, and will eventually drain back into the engine. Viable solution? yes? no?
Be very careful with filters they most likely will freeze and if the case pressurizes you start blowing gaskets and or seals.
Also make sure to have a 1/2 inch slit lengthwise close to the engine in the breather hose just so if you have a freez up you do not blow any seals.
Just the hose going up and around the cylinder and finally ending up on top of the cylinder is all I have and never lost any measurable amount of oil.
A pressurized crank cases loose a lot of power. For maximum power it is beneficial to have a slight vacuum on the breather, but be careful this also will increase oil consumption especially in worn engines.
Also make sure to have a 1/2 inch slit lengthwise close to the engine in the breather hose just so if you have a freez up you do not blow any seals.
Just the hose going up and around the cylinder and finally ending up on top of the cylinder is all I have and never lost any measurable amount of oil.
A pressurized crank cases loose a lot of power. For maximum power it is beneficial to have a slight vacuum on the breather, but be careful this also will increase oil consumption especially in worn engines.
Thanks for the tip. I dont see a chance for the hose end filter to freeze if they are kept dry or has oil on it. But to be on the safer side I will probably route it into the airbox.
Also, for the record, KMS used to make a lockout clutch for the rekluse. I emailed Kelly, and this is what he said: "Recluse changed the design of their pressure plate. Their new plate in their design they placed holes exactly where my lockout would go. I do not know if it was intentional because my product made their product much better or if it was just coincidence."
He did also say that rekluse now makes an auto clutch capable of 100hp, which I confirmed with an email to rekluse, as it does not have that info (max HP capacity) listed on their website.
He did also say that rekluse now makes an auto clutch capable of 100hp, which I confirmed with an email to rekluse, as it does not have that info (max HP capacity) listed on their website.
S
simbatheking
Well-known member
Fuel
I’ve been boosting for about 6 yrs on sleds and now my snowbike and have always found straight av gas is the ticket. I always ran 10psi on my sleds and will run 10psi on my bike once I get a smaller turbo. (My current turbo is too big). Av gas is very consistent and 100octane or better. It smells good and evaporates fast and doesn’t make ur hands stink if u spill. 3-6k is not that high elevation and I would listen to Sweden turbo and only run 7psi. On a 4 stroke at 11000 rpm the crank only pushed half as many times as a 2 stroke so it has to put a lot more strain/pressure on the rotating assembly in order to make the same hp. I suck at explaining my theories but that’s how I think. Run straight av gas. Don’t listen to people who say the lead will destroy your oxygen sensors because I’ve never replaced mine and have about 11000km on the sensor
I’ve been boosting for about 6 yrs on sleds and now my snowbike and have always found straight av gas is the ticket. I always ran 10psi on my sleds and will run 10psi on my bike once I get a smaller turbo. (My current turbo is too big). Av gas is very consistent and 100octane or better. It smells good and evaporates fast and doesn’t make ur hands stink if u spill. 3-6k is not that high elevation and I would listen to Sweden turbo and only run 7psi. On a 4 stroke at 11000 rpm the crank only pushed half as many times as a 2 stroke so it has to put a lot more strain/pressure on the rotating assembly in order to make the same hp. I suck at explaining my theories but that’s how I think. Run straight av gas. Don’t listen to people who say the lead will destroy your oxygen sensors because I’ve never replaced mine and have about 11000km on the sensor
Thanks for the info and advice, and yes I'm also listening to Swedenturbo's advice. What bike are you running your turbo on? From the census that I'm getting reading up info, specifically on the yz450f models, they can easily handle 10PSI, and 7PSI for the KTM's is the sweet spot.
Will the AV fuel cause any damage to fuel lines or seals? Do I have to drain the tank for storage? (in between rides storage and summer storage?) Any specific storage tips if I want to buy say 10-20 gallons at a time? Does it go bad faster than regular fuel?
