They had a sneak preview today for the RX-1 at the Mer-Maid in Mounds View, MN this evening. *I was very impressed, to say the least. *Here are my observations:

Sound- Incredible, quiet superbike rumble.

The RX-1 has a very low engagement speed, ~2500 RPM.

Weight- Yamaha won't really won't tell you but the factory engineers said that their target was 5% of the SRX. *One other interesting thing at the sneak peak I saw was a sticker one the RX-1 models that said "Prototype front bumper, please don't lift or bounce" *Why? *Looked indentical to the Viper bumper. *Maybe they did not want the attendees to try to lift the front. *One of the factory engineers said,"The amount of weight is not as important as cneter of gravity", thats fair.

Spin oil filter!

Oil change interval 3000 miles.

Lifter adjustment 26,000 miles!

They tested the RX-1 in Alaska to -30F and it started!

Dry sump- no oil to slow down cold starting RPM

No storage compartment.. bummer

Plenty of sophisticated die cast parts and mfg methods.

Overall I liked what I saw and I am pleased with the direction Yamaha is taking!

Maxwell

At -30 degrees F did they need ether to start it? http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/confused.gif

The engineer that I spoke with did not say.. So I don't know..

sorrry,
Maxwell

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Sharkey @ Feb. 01 2002, 11:18pm)</td></tr><tr><td id="QUOTE">At -30 degrees F did they need ether to start it? http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/confused.gif[/b][/quote]
Why should they need ether? *A well maintained and tuned engine should have absolutely no problem starting at those temps. *Keep the oil clean (I&#39;d use synthetic myself due to the extreme environment), keep the coolant fresh, keep the battery to full charge during storage (I&#39;d replace it every two or three years as a maintenance interval), as well as keep the fuel properly dosed with stabil during storage. *A tsp of oil in the cylinders during summer storage would keep the cylinders from gunking up and sticking. *Set aside the starting fears, and be more watchful for early production bugs. *Methinks Yammi has a good thing going here. *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/biggrin.gif

The production sleds will have a storage compartment in the nose. *They are also trying to get the weight within 3% of the SRX in time for production.

sounds good, but i think they could have saved some money and put the sled in a deep freeze instead of going to alaska for the big chill. LOL * http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/biggrin.gif * *you know like when john candy was winter training the jamaicans.

Do they make large enough freezers that get that cold?

jetrep,
*where does your family keep the bacon ? see just toss out the bacon and put the rx-1 in there. * http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/wink.gif

I was up In Houghton Mi. this past weekend and the factory was testing the RX-1 over in Greenland and had a chance to see it take some whoops at speed. It took them very good. We did not know what it was at first but noticed that all the other sleds were bouncing and darting all over the place and it looked smooth a silk. Then we saw it up close on its side never got to see the motor. It looks to have a large aluminum casting where the front a arms attach looks great as long as you don&#39;t hit something big. We tried to talk to the Tech working on it but he was straight from Japan and didn&#39;t have a clue what we were asking. The rear suspension looked very good as well.

* Looks like Yamaha has a good thing going.
* Jemms

Yamaha should come with a wheel kit for summer also for 8500.00 U.S. Could you imagine making it road legal, that would be fun. I&#39;m sure some owner will convert it at least for straight line running. http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/wink.gif

Yamaha did such a wonderful job redesigning the chassis, front suspension, and engine. *Then they leave the ancient technology pro-action rear in it. *I have 2 Doo&#39;s and 2 Yamaha&#39;s. *The biggest disadvantage the Yami&#39;s have to the Doo&#39;s is the rear suspension. *No matter what adjustments I do, and I have done everything, I can not get the Yami&#39;s to handle, or ride nearly as good as the Doo&#39;s.

[One of the factory engineers said,"The amount of weight is not as important as cneter of gravity]

Tell me this as i&#39;m trying to get it unstuck. To me weight is a big part of things.

How come yamaha droped the hp on the mountain RX-1 to 145. *Or did they drop both mountain and sport. *

Got the info on there website.

Just like why did Cat drop F-7 to 138 instead of 140. I will bet they both do not put out even that much. *They are turning the 4 banger alot slower than bike you know. Cat has said their racing 440 is more powerful every year, Polaris too. If you added up all they claim they would be 120 horse, not 99 like they stated this year. You have to take every thing you hear and lessen it 5% so you do not expect too much and are pissed off all year. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/confused.gif

Yes they do make a freezer big enough to test a sled I was in a ice cream warehouse *today

they only keep it at -28 in that one. * They drive a forklift in that freezer *you ought to see that sucker ice up when they drive it out into my truck. * I agree why go to alaska *there are big freezers all over the country * Oh yes *at reefer trailer that hauls the ice cream is also big enough and they have wheels on them so they can move the freezer to japan if they want to.

alindazip,
*see that you have it all figured out without sending the new rx-1 to the great white north, they can just buzz around in the back of your truck.

*ps. how do you say your handle there ? what does it mean ? thanks.

The RX-1 and the Mountain RX-1 was the snowmobile of the years its a revelation and have a rumors to yamaha kick ass with a 220 hp in 2004 * * *.....
yamaha rules for 4-strokes......

mtn rx-1

okay, sure ? *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/confused.gif *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/sad.gif

Seen this sled about a week ago looked very good and sounded even betteryamaha done a good job. The egineerstold us their would be a storage compartment when the production sleds come out. they also said they got 118 to 120 mph out ofit on some us. trackheard it was 12&#39;300 canadain
http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/wow.gif

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (paul yarek @ Feb. 14, 2002, 10:37pm)</td></tr><tr><td id="QUOTE">mtn rx-1

okay, sure ? *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/confused.gif *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/sad.gif[/b][/quote]
It&#39;s going to be a serious machine!!! Considering it has 45% more torque than any 800 twin out there!!!

It&#39;s 65% and that&#39;s only on the low end. *By top (rpm&#39;s) the other motors have caught up. *My hope (with good hook up) is that we&#39;ll be way in front by then.

Just think of the aftermarket capabilities though http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/smile.gif *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/biggrin.gif

radguy,
*i have no doubts in my mind about the rx-1, i used to ride yammers 30 years ago then there was that chasing a wife thing. now i am back at sledding and have a spot in me for yamaha even when i am on a doo.

Plenty of aftermarket stuff. * Will they need it though??? *I think so... Isaw *a *cat four stroke a few weeks ago, *very quiet. *I talked to the driver and he said ot would only go 45mph or so. *I hope with the bigger displacement in the rx-1 it will be able to hit 3 digits. *Put on some Yoshimura full exhaust and some heads and port that bad boy, * she&#39;d be a screamer!!!!!!!!

Nick gehring,I heard that two guys got radared (sp) on rx-1&#39;s,one was 124mph. and the other was 126,i&#39;m not sure the distance they were radared at but thats pretty darn fast!I also have heard that the rx-1&#39;s weight is 550pounds! but you can always add 20 or 30 pounds to that...at least that what i heard!I cant wait till the fuel injected rx-1 comes out in a few years, they have the technology for it allready, u can bet it will be on the rx-1 soon. http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/smile.gif

4 stroke engines start at -30 no problem. I go to work in a 4 stroke. Tow my sleds with it too. What about airplanes? Np.

This is going to be the sled that changes all snowmobiling!

This could be the best thing that ever happened to snowmobiles. I never had any problems starting four stokes in
northern manitoba. All I can say is Keep them Coming !!!!

What the rx1 only did 124. *My Mach can top that and so can all the thundercat and XCRs out there. *And its not even in production yet. *So by the time you get it it probably wont even do 120. *

I bet you will feel pretty smart as your passed on a lake. *

Whats with the drop in Hp with the mountain sled. *I bet there are more drops to come just like with the viper. *

A sled with that engine should do 130mph in a strong head wind. *If it cant they can keep it.

BE CAREFUL WHAT YOU ASK FOR. YOU MIGHT JUST GET IT. WHEN ALL YOU 4 STROKE LOVERS ARE DONE HUGGING A TREE MAYBE WE CAN ALL GO OVER TO AL GORE&#39;S HOUSE AND SING KUMBA YA.

It&#39;s getting kinda old with some of you guys implying that we are tree huggers just because we want an RX-1. *Let give you some of my reasons again, please note that I don&#39;t mention emmisions!

#1. Fuel economy
#2. No injector oil needed. *I will change the oil at the begining of the season for less money than I would spend on injecter oil for one weekend of riding on my MachZ.
#3. Durability. Valve adjustments at 24,000 miles (He!!, how many 2-strokes live half that long)
#4. No more rejetting

Will it be faster than my MachZ, I dought it. *But there is always someone faster anyways.

MAYBE JOHN DEER CAN GET BACK IN THE GAME. THEY&#39;VE ALREADY GOT SOME PRETTY KICKIN LAWNMOWER ENGINES.

I dont know about you but i use about $150.00 dollars of injector oil a year. *Even if i used 300.00 i would still be ahead of you for the price diffrence of the machine. *

Fuel eco. *If you accually think you can circle the globe in this sled on one tank of gas your on drugs. *Fuel eco will probably be about the same as a Mach Z. *4 cylinders with 5 valves is going to suck it down. *Plus its still has carbs. *When your reved up to 9 or 10 thousand RPM your everything but efficent. *

Valve adjustment at 24000miles well thats probably longer then the machine will last. *I have never seen a machine with 24000miles that had a body worth saving. *(Steering loose, Suspention warn or warped, Clutches warn, every bushing gone.) *Plus if you accually thing this engine will go 24000miles with out anything going wrong your dreaming. *This is sleding not cycling. *Starting a engine that has been sitting at -20c and goes to operating temp only to be shut of and go back to -20 and start all over again. * Stuff will brake. *

Infact the only thing i have ever gone bad on me was a CDI for my 500 mxz made by TOYOTA(Denso). *Im sure the CDI or computer for the RX-1 is a little more pricy and so is every other part for the yamaha. *I bet the heads alone on that engine is worth more then the 500cc rotax twin.

My point is that you will not gain anything by going to 4 stroke. *Sure it will probably a bit more reliable during the season but overall the same problems will come out.

Rotax has a 800 twin coming out with a 800 SDI they claim way better gas milage, %50 reduction in hydrocarbons and %50 reduction in oil use. *It also has a knock sensor and all the little failsafe goodies. *And more power. *If this technology makes it into a 809 triple i will probably use less gas, Have less problems, *Oil use will be so little it wont matter, and will probably still smoke you on a lake. *

My advice is to just wait and see how the 2 strokes do with the DFI or SDI because from what a few magazines are now saying this is where the market and manufactors are going. *4 stroke are not taking over because there is no advantage that they offer. *All they offer is extra weight. *

Im not saying the RX-1 is a bad machine, *What im saying is that i dont think it will be that special once the new 2 stroke technology is out and running. *The 2 strokes will almost have every advantage on the RX-1. *And sure the RX-1 has good looks but i never bought a machine on looks and i wont start now.

For starters, I&#39;m paying roughly the same price for my RX-1ER as I did for my 99 machZ, $8,400.00. *Plus with the RX-1, I get electric start and reverse. *So if you want to compare apples to apples, I&#39;m actually paying over $800.00 less for the RX-1. *So I do have and advantage there.

2nd. My mach Z gets 10 mpg&#39;s, talking to yamaha guys, the proto type sleds that they are testing in Michigans UP have been averaging 200 miles per tank, I get 100 on my Mach!

3rd. One of the proto type sleds has over 20,000 miles on it and it has had only one problem, a valve spring broke. *If that happend to me my 5 year warranty would cover it.

4th. DFI is not the answer, it&#39;s still a 2-stroke.

DFI is the answer. *You are going to be suprised what the DFI system does for a 2 stroke.

Will it eliminate injecter oil? *Will it eliminate plug fouling? *Will it get 18-20 mpg&#39;s? Will it run the same from -10 below to 45 degree&#39;s? *Will I be able to start it during the summer let it idle and bring it up to temperature to get things lubed without loading it up? *These are some of the reasons 4-strokes will prevail.

I thought like you once machzzzz1 until I rode my friends YZ-400 4-stroke.

No, Yes, Yes. *

Its the way. *Who cares if you can run it in the summer. *The weight of the 4 strokes will be there downfall.

What weight are you talking about, the RX-1 weighs less than our MachZ&#39;s!

Well i started out driving 4 stroke atvs but 2 strokes are way more fun and cool. *

Outboard 4 strokes suck. *2 strokes are way cooler with more reliablility. *

Maybe in dirtbikes the 4 stroke is better i wouldnt know but in a sled i truly belive that 2 strokes will always prevail.

Also if the RX-1 does weigh less then the mach z then im sorry thats an other good point for the RX-1. *But most of that is probably the newer chassie. *THe Mach Z engine must weigh less then the RX-1 engine. *If skidoo would pull there head out of there A$$ and do somthing with the 809 instead of having it come back year after year the same thing with no new incentives its no wonder they dont sell but if they do wake up the RX-1 will look plain real fast.

I&#39;ve got my RX-1ER Limiteds coming but I love all sleds. Ski-doo needs to make the Mach Z in the edge chassie period. Alot of guys would buy one if they did this. People have been putting the Z engine in MXZ 440 chassies for a few years and you can guess what they do after the transplant. And they use stock exhaust, so it&#39;s an easy swap.
Caleb

I hope you mean ZX. *The polaris Edge would be a step back.

DOES ANYONE HAVE LEGITIMATE TORQUE AND H.P. NUMBERS FOR THE RX1? I DOUBT IT. IT&#39;S ALL HYPE TO GET THE MONEY OUT OF YOUR WALLET. REMEMBER THE 92 VMAX 4? THAT WAS SUPPOSED TO BE A REAL SCREAMER TOO.

Mack Z as a good machine but is gaz/milage was bad the RX-1 with her power was the most economique. the best gaz//milage//power of any sled * * look this avantage http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/smile.gif

You have to wonder when the best Yamaha can give you in terms of performance are percentages measured against past machines. This Yamaha engineer that says weight isn&#39;t everything must like em plump.
Well lay off the sushi Yamaha and trim that sucker down everywhere you can. Ski Doo has it right in FORM FOLLOWS FUNCTION.
LOOKS AINT EVERYTHING! because if it rocks past the rest and is built solid I&#39;ll buy it(for the right price).
Give us the true numbers Yamaha because us sledheads thrive on specs when we can&#39;t test drive.

My two cents.

I read a few of machzzzz1 post on the rx1, it funny how he has a lot of knowledge on a sled that hasnt been released. *Telling about how its not going to be that good then telling everyone how good the knew doos are going to be and there not released yet either. *Sounds a little biased to me. *Of the four mag reviews I&#39;ve read on it they are all impressed at how much power the rx1 has. *Its going to be a screamer, thats my unbiased guess on a sled that hasnt been released. :-)
With a weight similar to the srx, but the same or lighter than a machz, it will be interesting to see how it handles on the trails with its "balanced weight". Less hp than the machz but more torque. *But the easier and probably cheaper hp upgrades will be nice.

Torque,Torque,and More Torque. It&#39;s going to Rock. All I caed about hearing was on it&#39;s torque and the fact it beat *the2002 SRX by 6 1/2 sled lenghts in the quarter mile. What else needs to be said? That says it all since we all know what kind of animal the SRX is. And no I doubt it will beat the T-cat- or MachZ on the top, but may with the proper clutching.
Caleb http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/biggrin.gif

We&#39;ll have to see how it will do compared to the machz and the now deceased t-cat. *Tests so far put it in the mid high 120&#39;s. * Even if it doesnt beat their top end how far will they have to go till they catch up to it. *Hopefully yamaha doesn&#39;t do to many changes to affect its performance, and all the reviews are what its going to be.

SRXBOY. *I only say good things about the REV (new skidoo) Because i talked to a few people that have ridden them and they say its so good that they couldnt go back. *Also if you look on paper the new design does give you (the rider) every advantage in handling by placing you where you want to be for aggressive riding. *

As for the RX-1 I dont know what it will do and have never even sat on one. *But i remember how yamaha described the VIPER before it was released and that makes me wonder about the RX-1. *I remember even the magazines were saying the viper was faster then the SRX up to a certain speed. *But ive seen the two race and the SRX just leaves it. *That just shows to me that the Magazines say what ever they have to to satisfy there sponcers. *

I hope for you and all the people that already ordered one that its everything yamaha claims and that they dont de tune it and cause a loss in preformance. *

As for how far a Mach Z will have to go to catch up. *Well in a real drag race where everyone has 1000 studs it will probably take awhile. *But on the trails finding that kind of hook up to hold the torque will be very hard if not imposable leaving only the mid range and top end to do any damage. *My guess is that it would be close.

Machzzzz1, I was only trying to give you a hard time. * I agree about the let down yamaha has given in the past. *I wonder if *ones that own the Viper know how to set the thing up or are they running it out of the box stock? * I&#39;ve heard lots of good about them and bad, so maybe there not clutched and jetted properly. * That can take away a lot of performance as I&#39;m sure your aware. * You hear a lot of complains about good sleds, not just yamaha&#39;s that dont seem to run how they&#39;re supposed to.

I have a 98 srx and have the jetting perfect (8400) and the plugs, light tan, the transfer is good. *Another srx rider rode mine and couldnt believe how good it went, his was stock and never touched it. *His shifts at around 9100 which is good for six length alone. * I assume he&#39;s running rich and he has nothing off the line. *

It should be a good race when the machz and the rx1 go head to head, of course I&#39;ll put my money on yamaha. :-)

I&#39;m very proud of the folks that are stepping up to the plate to grab a first year RX-1. *You no doubt have a lot of patience. *If the RX-1 runs true to Yamaha form, you&#39;ll need plenty of patience. *
Yamaha&#39;s hall of shame includes the SR-V(you&#39;ve got spare pistons, don&#39;t you), the &#39;82 SRX 500 (stillborn), the first Exciters (they&#39;ll out accellerate the muscle sleds,yeah,right), the V-MAX 4 750, &#39;97 SRX (exploding tracks and bent cranks), and the MUCH overrated Viper.
I think it&#39;s a wonderful concept, but I&#39;d bet a dollar to a doughnut a year from now, this forum will be full of critics hammering on the RX-1. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/wink.gif

I agree with what you guys are saying about the problems Yamaha has had in the past. The SRV, Exciter and any other machine Yamaha made in the 80s just plain sucked. But through the 90&#39;s they changed their tune a little. Yes the V-max 4 had its problems but they worked them out and it turned out to be a pretty solid sled. The SRX had its problems too but it followed the same path as the V-max. The rule is give the RX-1 a season or two and it will come around just as the Viper will. Aren&#39;t you a buch of ski-doo guys talking? I ride with a bunch of ski-doo guys and there is one word that comes to mind...RECALL! Or how about broken pistons, blown CDI boxes, running a little hot? These are all problems I have experienced first hand from brand new ski-doos. Ski-doo has had just as many problems in the past as Yamaha and my ski-doo loving friends will even admit to that. I think you guys have a little case of selective perception. I am not hacking ski-doo, Yamaha has its problems too, but so does everyone else. My point is lets drop the brand loyalty and be logical. As for the DFI comments made earlier...thats what forced OMC to go out of business! They seemed to have a hard time making it realiable. Besides it would still be a two stroke which means twice the beating on the crank and bearings in comparison to a four stroke.

I admit that doo has been slacking the past two years but at least they don&#39;t release false number&#39;s, not to my knowledge anyway. We&#39;ll just have to wait and see if the RX-1 holds up to the hype, if not then lots of people are going to switch brands. An other thing, Doo&#39;s triple sales have been going down dramatically in the past couple of year, people are now bying trail and crosscountry sleds which the RX-1 doesn&#39;t appear to be. The only reason to buy the RX-1 is dependability and millage but I&#39;m not sure how this could be achieved with a motor running at 9000 -10000 RPM cruising speed. I would rather place my money on doo&#39;s DFI engine.

I&#39;m curious about top end speed. Torque is how fast you get there when the engine is accelerating, but top speed is HP, assuming you have the torque to pull the RPM required to reach maximum HP. Weight is a second order factor in top speed. Aerodynamic drag and how efficiently the entire drivetrain gets the power to the snow are the primary factors. If the RX-1 has 145 HP on tap, I don&#39;t think it&#39;ll run with a Mach or TCat on the top end, all other things being equal. We&#39;ve all heard of claims that "my sled is box stock and runs 130 MPH", but this is just barroom BS. A box stock, unstudded Mach Z might run low 120&#39;s, but that&#39;s with 150+ HP. 145 HP is 145 HP whether it&#39;s a 4 stroke or a 2 stroke. Also, I agree completely that with that much torque on tap you&#39;ll absolutely run into traction problems when you nail it out of the hole. I suspect that the thing will have a brutal midrange pull, but with that much torque, how long are you going to be in the midrange RPM band when you punch it anyway? These CVT&#39;s go right to maximum RPM anyway. Just my 2 cents. I must, however, applaud Yamaha in going this route regardless of what the outcome is. The thing at least sounds awsome.

This is a long one...
Roton as far as top end numbers go I am very curious also. But when you think about it there are a lot of factors that come into play. First of all the mach z will not go over 120. The fastest sled out there is the mach z and has been radared at speeds no higher than 118. Another thing as far as HP goes is, consistency. We know what the dyno numbers are but what are we actually producing on the trail? I ride an SRX which is supposed to be around 140 but we all know thats not the case when I am cruising down the trail on your average Saturday afternoon. So we have to consider how much power we are actually producing and why we are producing these numbers instead of what the dyno guys are saying. The answer is carburation. Smaller carbs produce much more consistant numbers than larger ones. Granted there is an overall power loss but there are ways around that. To give you an idea of how much carb size can effect consistancy...in WWII they used carburated motors in military plains...how did they get them to produce consistent HP numbers despite varying alttitudes and temps? They used really small carbs! I am curious to see what kind and size carbs that Yamaha is using on this engine. If they are using really small carbs with a high velocity set-up then chances are the actual horsepower will be closer to what the dyno guys are saying. If a mach z dynos at 160...how much is it producing on the trail? When that sled is dynoed it is leaned out as much as possible to get the most hp for the test session. Once it is jetted back for trail riding there is a significant loss. Some sleds lose more than others at this point and its the size of the carbs that has a big effect on how much is lost. I believe the mach z&#39;s have 38 mm carbs which and the RX-1 has 33 (not sure about that) if this is the case it implies that the RX-1 will be producing more consistant numbers than the mach and this may be enough to bring them very close on the trail despite the difference in numbers on the dyno. As for top speed...maybe the torque will allow for taller gearing which will result in top speed.
* * As for those who are worried about a sled that revs at 8-10 grand all of the time. I am told...and this makes sense because of the torque...that the sled tends to rev reletively low until you really get on it, but before that it is not much different from any other two stroke as far as rpms go for cruising. We&#39;ll know if this is true next season when we actually get to ride them.
* * As for yamaha not releasing numbers...they probably don&#39;t know what it will weigh because its not even ready for production yet. Besides everyone lies about numbers your dreaming if you think anyone is telling the truth.

Mikuni BSR37 X 4

http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/inlove.gif

I spoke with a friend of mine earlier and we were talking about my post. He is into sleds and bikes. He claims that generally speaking four strokes are much more consistent than two strokes. I don&#39;t know why...he never explained. I don&#39;t know if this is correct but he seems to know his stuff. As I said before we&#39;ll see when it comes out.

There&#39;s no question that 4 strokes produce more consistent power over a wider latitude of conditions than 2 strokes. Whether the RX-1 can out-topend a Mach Z will have to be argued about when they line them up. What I&#39;m saying is that without fundamental differences in how the power is transferred from the engine to the snow, there&#39;s no way that 145, 160 or 172 HP in factory sleds are going to run anywhere close to 130 MPH. As a rough rule of thumb, speed increases as the square of the horsepower. Of course this assumes that some things are constant, which in general isn&#39;t true, but most of these are second order effects. Let&#39;s say that a Mach Z runs a radared 120 MPH under a certain set of conditions. Let&#39;s also say that it&#39;s drivetrain is running as it was designed and that it has 150HP for the sake of argument. To run 130 MPH, it would have to produce 176 HP, and this assumes quite a few secondary factors don&#39;t get into the act. Add those in and you&#39;re probably looking at more like 190 HP. I agree that the Yamaha will no doubt be easier to clutch and gear because of the ruler flat torque curve, but 145 HP, if that&#39;s what it is, through a standard concept CVT, gear box and most of all, inefficient track slide mechanism won&#39;t pull 124 or 127 or 130 MPH in stock form unless you push it off a cliff. No sled will.

Ooops, I should have said that HP increases as the square of the speed, not vice cersa. Sorry.

Roton do you know why four strokes are more consistant? I am just one of those guys who loves to learn. You seem to know your stuff. As for what you were saying about top speed. Your absolutely right....it takes so much more power to gain so little which to me says that the mach z, and other muscle sleds will be close because there is not enough of a difference in power between them to make any one of them significantly faster than the other.

99SRX700,
* * * I think the major difference in the better consistency of 4 strokes over 2 strokes comes from the 4 strokes ability to better control the amount of fuel that is burned in the combustion chamber. This isn&#39;t caburetion oriented specifically, but the fact that you have valves that control when the fuel enters and leaves the camber rather than relying on the piston, port timing and pipe to control this. A 2 stroke uses it&#39;s pipe to both scavenge the exhaust gases out of the cylinder when the piston moves down and stuff the unburned intake mixture back in as this mixture tries to get out the open exhaust port as the piston comes up. Since a 2 stroke has these two things happening on every crankshaft revolution, there is no absolute separation between the two. While these two conditions can be addressed with the same hardware for a limited set of conditions (RPM, temperature, etc.), there will be certain compromises to both the intake and exhaust phases in any case. You won&#39;t have a the best bottom, mid or top end at the same time. These can all be made to be acceptable, but no one range will be optimal. If you compromise any, or all of these in some way, you will be compromising performance and fuel economy. Lake porting and race pipes will give you a great top end, as an example, but the bottom end and midrange might make the sled run terrible at the bottom and midrange. This is why there is more performance to be had in the aftermarket. Other than production tolerances being wide from the factory (the term "blueprinting" means that the motor is checked and rebuilt to exact factory specifications), more power can be had for certain conditions, but more than likely, one will compromise some other range of performance in the process.
In terms of pipes, temperature also gets into the act as not only does the pipe have to be sized correctly for timing reasons, but the speed of sound changes with temperature as well. Expansion chambers rely on the time it takes the sound pressure wave to travel in the pipe and this depends on not just the distance it travels, but the temperature. Hot and cold conditions play a large role in pipe performance. This is why most factory exhausts are insulated. Not only does it make things safer, but it helps keep the pipes closer to their optimal temperature. Most aftermarket pipes aren&#39;t insulated because they are made more for a specific set of conditions (they&#39;re also cheaper this way).

In a 4 stroke, the intake and exhaust portions of the cycle are separated by a revolution, namely intake and compression on the first revolution and power and exhaust on the second. The intake valves open as the piston comes down on the first rev., the intake valves then close, the piston then goes up and compresses the fuel, the spark plug fires, the piston goes down, the exhaust valves open letting the exhaust out and the process repeats. This absolute separation between intake and exhaust functions independant of external factors makes the 4 stroke much more "tractible". It also means that for a given displacement and set of optimum conditions, a 2 stroke will have a higher specific power output because while it will always blow some of the unburned intake charge out the exhaust, it does all this on a single revolution of the crank, rather than two revolutions. In general, once you can physically separate the intake and exhaust functions, you have a lot more latitude in tuning ability. I&#39;m sure you&#39;ve heard of variable valve timing in some cars. This is where you can really start to optimize the whole power curve. Exhaust power valves in two strokes work to this end as well.

* I&#39;ve played with turbocharging a little, and this is one area where you can well imagine that 4 strokes will have it all over 2 strokes. Because 2 strokes have this inherent "blow through" compromise, a turbocharger will make this worse to some degree. You put a turbo on the RX1 and watch out.

* So to sum up: 2 strokes can be designed to work extremely well within a more narrow RPM, load and temperature environment. To try and make them perform adequately over a wide range of conditions requires much more compromise than do 4 strokes.

Nice job roton.

A 2 stroke is way better when using a belt clutching system like all sleds have. * This keeps the engine inside the powerband at all times when you pin it. *Now with the SDI fuel injection the injectors computer will know when to discharge the fuel, this will prevent the blow through and lower emmitions and make more power. *Because of this accuracy the new two strokes will probably have much better pipes made for more conditions. *

You are right about the valves. and how they are seprate but that only makes for more moving parts and more weight. *(More moving parts = less HP.) *Also the effeciency of a 4 stroke is almost 50% less then a 2 stroke because of the 2nd rotation. *

The best 4 stroke engine for a sled would be a rotary since they fire 3 times in one rotation. *

varible valve timing like in the hondas Vtec. *Has little to do with the timing even though timing is effectied. *What it does is give you the advantage of having a lumpier cam at higher rpm but a more mild cam at idle and low rpm. *Basicly it is to give you smoother idle and a nice smooth wimpy engine down low but the moment you hit the gas the valves will open up higher and longer giving you more power. *

This system uses sensors and servos and other crap to work and on a -20 day im not sure i would want that kind of stuff.

Ya... I agree with you machzzzz..........Just my two cents

What do you mean by blow through? If you mean raw fuel passing into the exhaust then DFI will not prevent this. Blow through is cured by the exhaust not DFI. A while back when DFI was making its way into the out-board industry I first saw how it acually works. DFI changes consistency because it does the carburators job a million times better which is great...but thats all it does. The result is a more precise fuel mixture which results in more consistency. Your still relying on exhaust temperature and the many other flaws of the two stroke. From what I have learned since this post came up from all of my gear head buddies DFI will still not be as consistant as a four stoke due to exactly what roton said. As for servos...DFI is what put OMC out of business. It is not at all a simple concept and is very prone to breaking. DFI is not the answer they still have a ways to go. I just hope they can find more solutions because I love my two stroke!

99SRX700.

THe dfi in the rotax 800 is not simular to the dfi systems used in 2 stroke outboard. *

For one the rotax engine uses 2 injectors, the reason they used two is to prevent blow by. *HOW YOU MAY ASK http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/biggrin.gif ? *Simple. *

One injector needs to inject fuel twice as long as two fuel injectors. *That mean that to get the right emount of fuel into the engine it needs to start to inject before the exhaust valves are fully closed causing blow by and bad emitions. *

Bombardiers system has two injectors per cylinder allowing the system to inject fuel at the last posible second so that blow by cant occure because the exhaust ports are closed by the time the high pressure fuel gets there causing a really good consitent combustion.

The other thing is that the bombarider system doesnt use the super high pressure like outboard DFI. *Its still high but its not the huge pressures that OMC had. *

And the last thing is that this system SDI only uses one injector at idle and low speeds causing better economy. *When you speed up the second one starts working to keep up. *

DFI is the way to go. *Carbs are outdated and now that this technology is out they should no longer be used. *DFI is a reliable system used in desil trucks and cars and the computer systems have been proven in cars and trucks for years. *

Bombardier needed the 2 injectors to make a 2 stroke DFI work like a 4 stroke one. *But i think you will find the new DFI 2 strokes to be more deadly and powerfull then any 4 stroke to come. *

THis technology is a new birth for 2 strokes.

DFI will not make the greenies happy, you&#39;re still injecting oil into the engine which is then combusted.

yeah buy mighty. *This oil has burn properties as well as lube properties. *Its not like a oil burning 4 stoke. *This oil is designed to burn and burn clean. *

Thats why syntetics are more and more popular.

Roton, on a four stroke engine you say it,s two seperate clycles, wich they are, but the exhaust and intake valves in between the exhuast and intake stoke are still open at the same time, its called valve over lap.
I thing in the next few years you will the *see the 2-stroke dye.
Not to many 2-stroke bike&#39;s on the road, the marine industry is going to 4-stroke mercury just releasted a 300hp 4-stroke.
F-1 bike racing this year is the first for 4-stokes.
M/X bike&#39;s racing 4-stroke&#39;s against 2-stroke and the 4&#39;s win there share of race&#39;s
Like it or not the 2-stroke will be a thing of the past!!

This is a very interesting discussion. In my own unbiased opinion the idea of a 4 stroke in a sled is something that has to be tried, if they dont they will never know if it would have performed. I personally think it will have alot of problems the first year on the snow. I also think that yamaha will be playing the numbers game to boost sales to the lab mice that will have to deal with the new rx1. Lets not fool ourselves yamaha is at the top of the list for false claims. I do like the looks though they have gotten much better in that area. I will stick to my 2 stroke for trail riding and jumping, but if i ever want to get lazy and just pin the throttle i will buy a chimp and watch him run across the lake because thats about how much riding ability is involved. *sorry flatlanders * * http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/confused.gif http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/smile.gif

All I know is that the current 2 stroke SDI from bombardier has the same emmitions as there 4 stroke. *Now they didnt even put a catalyitic converter on it yet so theres even more enviromental crap they can do.

SO if the greenes arnent happy now they will never be and then can come and protest infront of my house and i will pull one of them aside every now and then and smack some sence into these ranting losers.

Yammy seems to be always finding a way to impress the competition!!!!!!!!!

I saw and heard the RX-1 and spoke with the engineers as well, I don&#39;t like that sled anymore. I thought it would be great but Chris Vincent could not even get the sled to jump moguls at the Fargo Dome Super Rip Off Race! It sounded like a broken Harley when wide open. That muffler design has got to go!