Everything looks perfect except the cvt

eric82930 · May 19, 2019

https://www.snowmobile.com/blog/201...thing-new-life-into-its-svx-450-snowbike.html

At least its a 2stroke so might still be fun even with the cvt. If it was a single cyl 4stroke cvt, it would be like riding on a one ski Polaris Rzr....

Makes a conversion kit look pretty silly to me.
Click the patent link and it also shows a 2 ski version with no running boards kinda looks like a phazer.

dooman92 · May 20, 2019

Good deal

Lots of positives. Hopefully it makes it to market. Hats off to artic cat for not giving up on the idea.

M5- · May 20, 2019

If anyone can pull it off it would be Cat as they co-own the patent on the monorail design with Camso which is how Cat was able to develop the Alpha.

M5

barkbuster · May 20, 2019

Looks like a hand brake on both sides, and posssibly a thumb thottle?

byeatts · May 20, 2019

eric82930 said:
https://www.snowmobile.com/blog/201...thing-new-life-into-its-svx-450-snowbike.html

At least its a 2stroke so might still be fun even with the cvt. If it was a single cyl 4stroke cvt, it would be like riding on a one ski Polaris Rzr....

Makes a conversion kit look pretty silly to me.
Click the patent link and it also shows a 2 ski version with no running boards kinda looks like a phazer.

All CVT transmissions scrub power, They are not efficient, Those who have sled background and knowledge know how temperamental dialing these in are and with changing elevations its a moving target, Not to mention all the weight , With limited HP it will not pace with a properly geared bike..

NEWDUCK · May 20, 2019

Glad to see the rider postition finally changing to where it should be.

boondocker97 · May 20, 2019

Wonder if the intent is to share similar power plant families as the "kid sled" patent?

https://www.snowest.com/forum/showthread.php?t=444046&highlight=kids+sled

GlennRMK · May 21, 2019

Looks like a single cylinder 2 stroke!

Hopefully its at least half an 800 at 400cc!

powdermuncher · May 21, 2019

1/2 a 800 is still 80 hp on a cvt fuel injected will eat any current snow bikes for lunch. the loss in the cvt will be more than made up by the gain in correct gearing = max HP at all times. The proper weight and balance of the bike and rider would be an other big plus. Even my die hard sled buddies agree that a proper factory snow-bike with some power would spell the end of Mountain sleds as we know them--it will take more than 80 HP for that to happen, we were talking more along the line of a proper 600 or 800cc sled engine.

byeatts · May 22, 2019

powdermuncher said:
1/2 a 800 is still 80 hp on a cvt fuel injected will eat any current snow bikes for lunch. the loss in the cvt will be more than made up by the gain in correct gearing = max HP at all times. The proper weight and balance of the bike and rider would be an other big plus. Even my die hard sled buddies agree that a proper factory snow-bike with some power would spell the end of Mountain sleds as we know them--it will take more than 80 HP for that to happen, we were talking more along the line of a proper 600 or 800cc sled engine.

from someone who has sold and designed custom sled clutching , Disagree , when bike is geared correctly which most are not i,m using all the power available with a tad overev to gain climbing track speed ,without the CVT weight or constant belt scrub. Advantage of CVT is ease of riding without shifting, Not enhancing the usable HP.

eric82930 · May 22, 2019

I knew if i put cvt in the title it would start the debate again to give us all something to do for the summer...
I know a light 80hp cvt 2stroke would eat any current bike but If the same 2 stroke was tuned to a broader 70hp with a cr six speed it would pack nearly the same punch and be more fun than the cvt.
A modern 450 is so broad I don’t think the cvt would help it at all and it would be boring as hell to ride.
I think we may get lucky enough to someday have a choice but then the Cvt600 bikes might not be able or want to ride with the 50hp conversion club and vice versa. I just don’t see them mixing well. When we were all on sleds we never invited the guy with the Phazer.

Either way the cat looks pretty fun out of the box especially for someone who doesn’t dirt bike

RMKcowboy · May 23, 2019

I'll do some additional stirring of the pot here- how/why would this concept be any better (or worse) than the Snowhawk? Chassis design/rider position is the glaring difference here. Who has ridden both a Hawk and a converted dirt bike side by side and can offer up some real world comparisons between the two?

David24 · May 23, 2019

RMKcowboy said:
I'll do some additional stirring of the pot here- how/why would this concept be any better (or worse) than the Snowhawk? Chassis design/rider position is the glaring difference here. Who has ridden both a Hawk and a converted dirt bike side by side and can offer up some real world comparisons between the two?

I’ve ridden both, there’s a reason why no one talks about them anymore. There just to bulky and heavy. The biggest concern with larger engines and CVT is rotating mass and added fuel consumption(which adds more weight to the machine).

byeatts · May 23, 2019

David24 said:
I’ve ridden both, there’s a reason why no one talks about them anymore. There just to bulky and heavy. The biggest concern with larger engines and CVT is rotating mass and added fuel consumption(which adds more weight to the machine).

No matter how one looks at it the CVT belt it is always scrubbing power, Thats why they heat up.with a big motor the ease of riding out weighs the inefficiency. However a direct drive is far more efficient and it allows for overev to gain more track speed when needed . The goal is to gear a bike correctly , I run Tall gearing and 1st will spin the track at 32mph, Most every snow bike is geared to low and 1st is never used. And with close ratio tranny it rocks.

eric82930 · May 23, 2019

I have rode a snow hawk years ago and it wasn’t nimble enough to go slow in the trees. At the time I felt like I could ride my sled better in the trees.
Regardless of transmission, The rider position I think will be better on a purpose built because the pegs can be closer to the track. This is what I've been riding this year and it looks real similar to the cat diagram. It is a 137 that is as short as a 120 conversion kit. It is a 60hp ktm360. This chassis did not work as a short track 120.. The over all length was too short to keep the front end down. It works way better as a 137 and it feels just like a dirt bike. This junker is pretty close to the mark, 10 more horses, less vibration and built at a factory would Make it perfect.

snownman · May 26, 2019

cvt...

byeatts said:
All CVT transmissions scrub power, They are not efficient, Those who have sled background and knowledge know how temperamental dialing these in are and with changing elevations its a moving target, Not to mention all the weight , With limited HP it will not pace with a properly geared bike..

you are not a cvt clutch tuner because cvt clutches are very easy to tune and work very well in changing altitudes...you are already very limited on power just due to the fact that the engine only makes around 50 h.p. . A two cyl. version of the bike would work a lot better...a little 440 rotax liquid mounted in the chassis would be perfect

eric82930 · May 26, 2019

If your cvt isn't changing with altitude then you are over revving at low altitude and leaving some hp on the table. They turn torque into rpm, torgue always goes down at altitude unless you have an altitude compensating turbo. Even the smallest 440 is twice the power we all have now so the cvt loss is negligable but we are still talking about a snow hawk type machine here and almost seems like it should be considered a different sport and go in another forum. A 440 snowhawk that weighed sub 300 would be hard to argue about pure performance capabilities and would definatly sell like hotcakes just not sure its the direction I want to go. We need some deep pocket mfgs to build one and see...

byeatts · May 27, 2019

snownman said:
you are not a cvt clutch tuner because cvt clutches are very easy to tune and work very well in changing altitudes...you are already very limited on power just due to the fact that the engine only makes around 50 h.p. . A two cyl. version of the bike would work a lot better...a little 440 rotax liquid mounted in the chassis would be perfect

They do not change with elevation, They only pace with Torque and Rpm and it has limits which it can adapt, Typically only in tune within 3k elevation change. They are always scrubbing power and generating heat. We have custom high hp clutch kits all over the country .Clutching is not Easy its very involved and a moving target.

tcgravy · Jun 12, 2019

byeatts said:
All CVT transmissions scrub power, They are not efficient, Those who have sled background and knowledge know how temperamental dialing these in are and with changing elevations its a moving target, Not to mention all the weight , With limited HP it will not pace with a properly geared bike..

I see this "CVTs are terribly inefficient" argument posted quite often, however, I still don't understand it. I have over a decade of sled background and knowledge, including dialing in clutches on 10+ sleds...sure it takes a lot of time and can be annoying, but once you do get clutching dialed in the results are always satisfying.

I've seen data & arguments for manual gearboxes being 95-99% efficient, and CVTs being anywhere from 65-85% efficient. These were measures of efficiency as either HP to the ground or fuel economy, and were at a single constant speed. At a single constant speed, a gearbox is always better than a CVT, sure. However, engines do not generate the same efficiency at all speeds or rpms (not even close, in fact). And we do not ride at a single constant speed. The benefit of the CVT is that it can vary the engine rpm as needed to access maximum power regardless of current vehicle speed or load conditions. And so, in variable load conditions, the CVT dominates by keeping the engine close to its peak power RPM at all times. This is true even before we factor in the drag and delay associated with each manual shift.

Snowmobiles/snowbikes experience a wider range of variable load conditions than any other powersport I can think of...and so, on snow the CVT persists as a transmission worthy of consideration.

And for the record, that's not to say CVTs are perfect. I believe there are also strong arguments for the following downsides of CVTs:
- the added weight and rotating mass
- they make your entire engine & drivetrain much wider
- they require tuning to setup, some maintenance, and periodic belt replacement

Further reading for anyone who is bored:
Olav AAEN's clutch tuning handbook - see PG 5 and PG 9 https://vdocuments.site/clutch-tuning-handbook-olav-aaen-1979.html
Visual graphs explaining the power delivery difference https://ieee.nitk.ac.in/blog/cvt/
CVT https://pdfs.semanticscholar.org/e483/9fd5c623ddec048da326d861395bc66041d8.pdf
Other discussion about CVT efficiency on snow https://www.dootalk.com/forums/topic/341004-cvt-vs-geared-transmission/

kanedog · Jun 12, 2019

byeatts said:
They do not change with elevation, They only pace with Torque and Rpm and it has limits which it can adapt, Typically only in tune within 3k elevation change. They are always scrubbing power and generating heat. We have custom high hp clutch kits all over the country .Clutching is not Easy its very involved and a moving target.

Yeah, that is why 330mph Top fuel dragsters and Funny cars use a centrifugal clutch system, weights and arms to apply 11,000hp to the track. . Totally inefficient. Perhaps they should use gearboxes?
You have been using a two roller secondary clutch system is why your cvt setups suck.
The difference between a two roller clutch and a three or more roller clutch is like..............well.....two dogs racing. Steroids, training, whatever. Even the two fastest racing dogs are still just two dogs racing.
Now put a Cheetah in the race and the fast dogs now look like slow turtles.
This is what the two types of clutches perform like. Think old school Cat clutch or a Paragon six pack(6 rollers).
Cheetah wins everytime.

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Everything looks perfect except the cvt

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