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Discussion Starter #1
If you sit down and figure power to weight on 2003 MXZ 800 and new Yam- Rx-1 1000 the Doo is 454 lb dry at 135hp avg. unless changes for 2003, and Rx1 is at least 540, most likely 550 with battery, at 145 or  150. That gives the Doo a full 10% power to weight edge, and way less rebuild costs than the Yamaha, and 14.5" rear suspension, and lighter front end. Just some thought to ponder. Now if Doo would release a DFI triple, that power to weight difference would be in the 20 % range, in a 500lb. chassis! I'm talking of a Doo 1000 2 stroke.
 

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You forgot to factor in that the 4-stroke is going to have about 50% more torque than the MXZ and that's what really moves a sled.
 

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Kinda like comparing apples to oranges isn't it ? Do you compare a diesel engine to a gas engine for torque and hp?
 

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</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (AKSUMMITX @ Jan. 19 2002, 12:49pm)</td></tr><tr><td id="QUOTE">You forgot to factor in that the 4-stroke is going to have about 50% more torque than the MXZ and that's what really moves a sled.[/b][/quote]
But torque only helps get the object accelerating. Once its past its torque curve, you need the HP for the top end part of the cycle.   I think I yamaha will accelerate very quickly(assuming that it DOES have 50% more torque, which I doubt 50%) but after 90mph or so, it will start to slow and be competitive with other sleds in the 800-1000cc range.  
 

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I doubt that it will have 50 percent more torque ,the more cylinder you have for a given cc the least  torque you have and also if you compare the same size engine of a 2 stroke and 4 stroke the 2 stroke  always has a higher torque. Remember the 2 stroke has a power stroke at every crank revolution. But I think in 10 or 5 years will all driving our overweight 4 stokes just like the motocross industry is doing now.
 

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Discussion Starter #6
If they engage the Yammy at 2,000 rpm it will have more torque there, but never all the way to 10000 rpm, I do not believe it will spin out 150 lbs. of torque at any Rpm. That is turboland folks.
 

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Just my opinion but the power to weight ratio thing is a bit over sold. You have to remember that the longer the run the less the weight will be a factor because the rate of acceleration is decreasing. Up to 600 feet power to weight means alot but after that hp is the rule.
 

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You should also consider that snowmoble clutching system the more rpm you spin the less effecient they are. So 10,000 rpm might not be a good thing.

Duane
 

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Can someone please tell me why a four stroke engine would have more lower end torque than a two stroke. For me that is very hard to believe since the 2 stroke will fire every revolution and the four stroke every other one. Please back up your opinion cuz everyone that tells me that has nothing to back it up with.
 

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I will never quit riding 2-stroke if there are restrictions on them HA id like to see them catch me on a 4!...As Lady K says You can have my 2-stroke ZX when you pry it from my cold dead hands!
 

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I think when somebody comes up with a better auto drive system than the
antiquated,bs, Belt drive were all forced to use now,We'll see way better
acceleration and top end numbers out of four strokes.The gear range on
belt drives doesn't utilize the power band of 4s which by the graph that
"mtrsprt" posted.we can all see is massive in comparison to the 2s.

Honda has already got the tranny answer. anybody ridden a rincon?
I bought a rincon last year for my wife.I was riding a suzuki vinson.
Eventhough the suzuki was rated higher in the HP dept.she kicked my but
every time so we switched,thinking it was weight difference.It wasn't.
The suzuki is gone now,replaced with a rincon

Now if honda would just pull their heads and put some of that technology
into the sled world we would have some bad a## 4 strokers.

Aaron
 

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Originally posted by Sharkey@Jan 19 2002, 11:04 AM
....If you sit down and figure power to weight on 2003 MXZ 800 and new Yam- Rx-1 1000 the Doo is 454 lb dry at 135hp avg. unless changes for 2003, and Rx1 is at least 540, most likely 550 with battery, at 145 or  150. That gives the Doo a full 10% power to weight edge....
Kinda makes you wonder why every race between a 800HO and an RX-1 that I've ever seen, the RX-1 wins..... hmmm.

Call it bias, call it whatever.... I call em' as I see em'.

NW Rider - please explain more. The CVT system that has been in use in snowmobiles since the dawn of time has stuck around because it works - and works well. It always keeps the engine in it's powerband (when required) and maintains the optimum gear ratio for maximum efficiency.... what's not to like?
 

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Originally posted by The Hossman@Mar 8 2004, 06:45 PM
NW Rider - please explain more.  The CVT system that has been in use in snowmobiles since the dawn of time has stuck around because it works - and works well.  It always keeps the engine in it's powerband (when required) and maintains the optimum gear ratio for maximum efficiency....  what's not to like?
Hossman I'll explain myself the best I can.
What I don't like about the cvt..The list is long but all stems from the belt and its short comings.I've spent a lot of time and money on belt experimentation
trying to come up with one that will hold up to the high temps of deep powder
riding yet still perform well on the trails or boon docking or just trying to get it
moving in the morning when it's cold.but have come to the conclusion that there
is no such belt...The group of people I ride with have the same gripes about
belts,but just chalk it up to the cost of having fun"just bring lots of belts"

As far as the overall design of the cvt,I agree with you that the ability to keep
the engine r's at peak performance levels is something to"like"but I also think
is overshadowed by the amount of HP robbing friction,inherant in V belts

The gear ratio thing I'm going to have to call theory right now cause I cant find
any documentation on gear ratios to compare.
I have ridden an RX-1,vinson 500 quad, sportsman 500 quad and a grizly 650quad
all with constant velocity trannys,they all feel hindered out of the hole almost like
they'r taking off in second gear,More noticable on the quads because of hookup
but still there on the sled.Ive raced all of my buddies with my lower HP honda and
always stomp them.We all agree it must be the tranny.It's just way more efficient.

The cvt has been around since the dawn of time and so have v belts.very few
things use a v belt anymore It's just a matter of time before somebody
comes up with something better.maybe honda or...who knows?

I gotta go. later! Aaron

Ps; Hossman. not a crack on the yami there. the R-X1 is high on my list of
sleds to look at in the fall to purchase.I just need to see how they do in the
deep stuff then I'm there.
 

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Ahhh... I see.

Heat has always been the enemy of belts. I agree 100%. But what other medium could be used?? I mean the CVT part (variable ratio) is definitely a good idea, and works best for both power and efficiency.

But, I certainly see your point to 'slow' take-offs on 4-stroke machines. But is it really a slow take-off, or a perception of it being slow?? Reviews have often read that the RX-1, for instance, doesn't feel that fast under acceleration, but watching the speedo (or lining up against another machine) reveals just how quick it is. Maybe it's because it sounds different.

I also find it interesting that cars are starting to use CVT's in them now (I know there's been a few botched attempts over the years), so obviously they have their virtues. Of course, they're just in 'ultra-economy' cars right now to further increase efficiency (like the Civic Hybrid...), but I wonder if they don't become more mainstream?

Interesting thought. Wonder if any manufacturer's have given this any consideration, and what could be down the road...
 

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The perception of slow take offs is a good question. sound is a big factor
and the R-X1 is pretty quiet for the guy riding it .Hmm something to think about.

The only thing I have for comparison are the quads and my buddies.Not very
scientific but all I've got right now If you come up with anything on this subject
please share.Didn't know about the cvt in cars.Cool something els to research on the net
Aaron
 

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Originally posted by DOO THE DOO@Mar 8 2004, 04:58 PM
I will never quit riding 2-stroke if there are restrictions on them HA id like to see them catch me on a 4!...As Lady K says You can have my 2-stroke ZX when you pry it from my cold dead hands!
Right on DOO THE DOO. :hallo1:
 

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Originally posted by NW.Rider@Mar 10 2004, 11:24 AM
http://www.off-road.com/dirtbike/aug2000/r...0fa/index2.html

"Hydrostatic drive" Beltless cvt.How cool is this?By By belt drives,wont miss ya.

Anyway this is what I'm talking about.I just didn't know what to call it nor that
was in the cvt family,just that it works very well.

http://cvt.com.sapo.pt/

This last link is cvt site in it's entirety. some good reading

Aaron
I don't really follow the 'quad' scene very closely (obviously), and had no idea that Honda had such a transaxle. WOW, that's cool! Leave it to them to build a better mousetrap.

The biggest enemy to this type of gearing is definitley going to be weight. I wonder how much that transmission weighs compared to a traditional set of clutches and drive belt??

Like I said before, I don't know if it is possible to invent a power transmission system that would be better than the CVT's currently used (and have been used for years...), but maybe it's just that no-one has ever thought to change it???
 

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LOL MTRSPRT,
According to that the 800 XCSP should whip em all, that power curve is nearly perfect. Nice smooth consistant curve, all the way to about 140 hp. Strangely enough I have never seen an 800 XCSP come anywhere close to any of those 3 machines. Where did you get that chart, it just isn't adding up to me. Also the XCSP has a higher torque curve than the Rev, WooHoo Polaris... lol not what really happens though. Watch the RX1's in drags, they spin like there is no tommorow, even the warriors, thats alot of weight to spin. they gotta have one helluva low end torque... I dunno just isn't really adding up.
Wayne
 
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