Re: BREAKTHROUGH!
EPS alone won't do anything when it comes to bump steer unless they also change the way the tie rods are mounted. As far as arm strength is concerned, that has nothing to do with it either. No offense, but until you actually ride fast and experience it, you wouldn't make such ill-informed comments.
sgilbert said:
EPS alone won't do anything when it comes to bump steer unless they also change the way the tie rods are mounted. As far as arm strength is concerned, that has nothing to do with it either. No offense, but until you actually ride fast and experience it, you wouldn't make such ill-informed comments.
AKrider said:
It looks like I'll be picking up a rtx tomorrow and a 42" skinz front end to play with in a few weeks so there will be plenty of stuff to look at.
bulldogbones
Expert
Would a steering dampener help the rider with arm fatigue??
If eps is there fix I'll be on my 08 a long time or switch brands.
bulldogbones
Expert
What about a power steering setup from say a can am??? They sell the PS setup for about $500.
bulldogbones said:
Nothing but a band aid.
Here is my theory and it could be proved wrong but I'm waiting for a accurate test to be convinced that bump steer is the issue. I think the main issue is in the caster. In addition to that the high ski pressure. The skinz front end addresses both. I honestly hope I am wrong because I have a idea for the bump steer. Changing caster is not a easy change.
My biggest problem with this thread is lack of time, I want to get involved in this thread but those that have seen my build, know I have my hands full. Not to mention I'm trying to find time to build a build thread on ty.
But since my mind is on the nytro front end now, I will probably do some testing as soon as I get this rtx in my shop. I want to check stock, z broz and skinz to compare them all.
AKrider said:
One of the other measurements that I plan to take on the '08 MTX when we put the SPG kit on is the difference in weight distribution. We have a 3 scale set up to determine what and how the weight will change from front to back. The sled does have a Mountain Tamer on it, but it should be interesting none the less.
Funny, I just figured out I was following rlcofmn's Nytro build over on the BCR forum. That build is really cool and the amount of time and effort going into it is very impressive.
For years my thoughts about the Nytro's handling woes were due to excessive caster. But after riding my buddy's Polaris Pro-R and my other buddy's Sno-Pro 600 after the Mayor's Cup race, I really started analyzing why my Nytro handled like a pile. Bump steer matches all the traits I experience. I'm not saying that the Nytro's steep caster angle isn't playing a role, but my feeling is caster alone is not the cause of the darting and instability. Yamaha's '09 geometry changes did slacken the caster angle by 4 degrees as well as bring in the tie rod mounts on spindle so they were closer to the subframe. Those changes reduced bump steer. I'm thinking the stock front end can be further improved by "tuning" the angle of the tie rod so it matches the lower a-arm.
Bulldog,
Yeah, a steering damper would help with the bars getting jerked back and forth (which I find to be mostly a minor annoyance) but it's not going to do anything about bump steer. The sled will still have a mind of its own, its just the damper will mute the feel you have at the bars.
Scmurs,
Great idea with the scales. Nothing like have some quantifiable data to help determine whether a guy's hunch is moving forwards or backwards. Your guys at SPG did a good job on the 4 videos. Initally I was thinking that spending an hour watching youtube videos was not going to be all that fun. But, the videos made me think about stuff I'd not considered and just hearing someone else describe what I'd noticed but never thought about because I adapted to it was very beneficial. The only way a guy gets a breakthrough like that is to ride other sleds. Kinda like my epiphany in March after my Mayor's Cup race.
For years my thoughts about the Nytro's handling woes were due to excessive caster. But after riding my buddy's Polaris Pro-R and my other buddy's Sno-Pro 600 after the Mayor's Cup race, I really started analyzing why my Nytro handled like a pile. Bump steer matches all the traits I experience. I'm not saying that the Nytro's steep caster angle isn't playing a role, but my feeling is caster alone is not the cause of the darting and instability. Yamaha's '09 geometry changes did slacken the caster angle by 4 degrees as well as bring in the tie rod mounts on spindle so they were closer to the subframe. Those changes reduced bump steer. I'm thinking the stock front end can be further improved by "tuning" the angle of the tie rod so it matches the lower a-arm.
Bulldog,
Yeah, a steering damper would help with the bars getting jerked back and forth (which I find to be mostly a minor annoyance) but it's not going to do anything about bump steer. The sled will still have a mind of its own, its just the damper will mute the feel you have at the bars.
Scmurs,
Great idea with the scales. Nothing like have some quantifiable data to help determine whether a guy's hunch is moving forwards or backwards. Your guys at SPG did a good job on the 4 videos. Initally I was thinking that spending an hour watching youtube videos was not going to be all that fun. But, the videos made me think about stuff I'd not considered and just hearing someone else describe what I'd noticed but never thought about because I adapted to it was very beneficial. The only way a guy gets a breakthrough like that is to ride other sleds. Kinda like my epiphany in March after my Mayor's Cup race.
I think I've figured it out. One thing I discovered about my laser set up was I had no reference to differentiate the arc of the spindle and bump steer. My old Ski-doo race handbook had the solution. Use two concrete blocks set parallel, 2" away from the side of the ski. You can then measure and determine if the ski is toeing in or out. The laser helps to give you a visual as to what's happening.
Still, I chased my tail for a while shimming the tie rod up and down. Then I recalled the tie rod needs to be parallel with the lower a-arm. I now believe the tabs on the spindle are too high and you cannot lower the tie rod enough to make it parallel with the lower a-arm.
00-NUKE's extension of the mounting tabs actually lowered the toe rod to make it more parallel with the lower a-arm and he saw improvement with bump steer.
I used an old Phazer II tie rod end that was a lot thinner than the stock Nytro. It allowed me to lower the tie rod further than is possible with the stock set up. It was not enough to make the tie rod parallel with the lower a-arm. My tie rod and lower a-arm were 2 degrees off from their respective angles.
From what I measured on my front end (which could be tweaked) the tie rod needs to be mounted at the same elevation as the lower tab.
View from the front showing what a parallel tie rod looks like.
I was surprised to find the inner tie rod ends were mounted in a vertical position. I thought they'd be mounted the same way as the outer tie rod ends. I don't believe shimming them will accomplish anything. A guy could maybe drill new mounting holes but I don't know if there is enough material to allow for new holes, especially if they ended up very close to one another? Raising the inner tie rods up on the steering frog will change the steering ratio. I think it will slow it down Raising the inner tie rods may also reduce the steering radius.
So.... I think this is the end of the road unless the '09 spindles have mounting tabs that are lower than the '08.
Another thing I noticed about my front end is different caster angles from one spindle to another. From racing, we knew the a-arms had a tendency to twist. They also have a tendency to twist when you catch something with the carbide. The twisting will cause your spindle to go more vertical, creating a steeper caster angle that makes the sled more nervous at high speed. The other thing that happens is your tie rod angle diverges even more from the lower a-arm. Your ski alignment gets out of wack and the bump steer gets even worse.
Still, I chased my tail for a while shimming the tie rod up and down. Then I recalled the tie rod needs to be parallel with the lower a-arm. I now believe the tabs on the spindle are too high and you cannot lower the tie rod enough to make it parallel with the lower a-arm.
00-NUKE's extension of the mounting tabs actually lowered the toe rod to make it more parallel with the lower a-arm and he saw improvement with bump steer.
I used an old Phazer II tie rod end that was a lot thinner than the stock Nytro. It allowed me to lower the tie rod further than is possible with the stock set up. It was not enough to make the tie rod parallel with the lower a-arm. My tie rod and lower a-arm were 2 degrees off from their respective angles.
From what I measured on my front end (which could be tweaked) the tie rod needs to be mounted at the same elevation as the lower tab.
View from the front showing what a parallel tie rod looks like.
I was surprised to find the inner tie rod ends were mounted in a vertical position. I thought they'd be mounted the same way as the outer tie rod ends. I don't believe shimming them will accomplish anything. A guy could maybe drill new mounting holes but I don't know if there is enough material to allow for new holes, especially if they ended up very close to one another? Raising the inner tie rods up on the steering frog will change the steering ratio. I think it will slow it down Raising the inner tie rods may also reduce the steering radius.
So.... I think this is the end of the road unless the '09 spindles have mounting tabs that are lower than the '08.
Another thing I noticed about my front end is different caster angles from one spindle to another. From racing, we knew the a-arms had a tendency to twist. They also have a tendency to twist when you catch something with the carbide. The twisting will cause your spindle to go more vertical, creating a steeper caster angle that makes the sled more nervous at high speed. The other thing that happens is your tie rod angle diverges even more from the lower a-arm. Your ski alignment gets out of wack and the bump steer gets even worse.
Glad to see you picked up on the Laser glitch that Scott and I talked about the other night. So whats the verdict? Stock configuration how much bump steer and where's it at? I would also like to see the 09 with a Accurate bump steer measurement, With the tie rod point being in a bit on the 09's making the tie rod shorter will have the same effect as moving the tie rod down, So this may or may not have fixed the bump steer from the 08's?
Good work!
And Trust me, there is no end of the road for playing with Nytro's
Good work!
And Trust me, there is no end of the road for playing with Nytro's
I've been looking for the online review I read about the '09 or '10 Nytro that stated the front end was about 40% better than the '08. The article mentioned darting and bump steer was reduced but didn't say it was eliminated. I've never ridden an '09 but my racing buddy told me over and over that the changes weren't enough and the minor improvement was not worth the cost to switch out components on a '08.
Based upon everything I've read, bump steer cannot be eliminated from the stock front unless the tie rod is parallel to the lower a-arm. Since Yamaha moved the outer tie mount to the inside of the spindle they reduced the bump steer. I suspect they moved the bump steer further up into the stroke where it isn't noticed as much but without an '09 to compare measurements to, it is just conjecture on my part.
I watched the youtube laser video again and the use of the mirror was pretty genius. That took the spindle arc out of the equation and allows a guy to focus only on bump steer. I've also learned the hard way that you have to pay very close attention to the tie rod length when changing its elevation because if you don't it will have the unintended consequences of moving the spindle and throwing off your measurements.
I also took a look at a photo of the Zbroz front end and I don't believe they eliminated the bump steer (I don't think they claimed to either). The tie rod is not parallel to the lower a-arm even when taking into account the gull wing design. Just take a string and make a straight line on your monitor from the lower ball joint to the inner lower a-arm mount. Than compare that angle to the tie rod and they are not parallel.
Based upon everything I've read, bump steer cannot be eliminated from the stock front unless the tie rod is parallel to the lower a-arm. Since Yamaha moved the outer tie mount to the inside of the spindle they reduced the bump steer. I suspect they moved the bump steer further up into the stroke where it isn't noticed as much but without an '09 to compare measurements to, it is just conjecture on my part.
I watched the youtube laser video again and the use of the mirror was pretty genius. That took the spindle arc out of the equation and allows a guy to focus only on bump steer. I've also learned the hard way that you have to pay very close attention to the tie rod length when changing its elevation because if you don't it will have the unintended consequences of moving the spindle and throwing off your measurements.
I also took a look at a photo of the Zbroz front end and I don't believe they eliminated the bump steer (I don't think they claimed to either). The tie rod is not parallel to the lower a-arm even when taking into account the gull wing design. Just take a string and make a straight line on your monitor from the lower ball joint to the inner lower a-arm mount. Than compare that angle to the tie rod and they are not parallel.
Found the article. It is mentioned on Bergstrom's site
http://www.bergstromskegs.com/oui/still ... e_past.htm
I was able to find a copy of it here on TY. http://www.ty4stroke.com/viewtopic.php? ... b5ac29dc17
I marked the front end sections in bold.
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Comparison Test: Four play!
Ski-Doo takes on Yamaha in the 130-horse 4-stroke crossover market
Mark Boncher
8/18/2008
4-STROKE FEVER - We tested all the new 2009 crossover and high-performance 130-horse 4-strokes from Ski-Doo and Yamaha last spring on the same day. We ran them through big bumps, powder, tight trails and more! Kort Duce photos
CARVE THE TURKEY - The easy carving and deep snow side-hilling ability of the XTX is impressive and predictable. Let's just hope snow/ice doesn't still build up under the tunnel.
NYTRO UPGRADES - There now are big snow removal slashes in the running boards.
The mechanical reverse lever still annoys us.
Adjustable couplers on the rear skid plus shorter front A-arms help handling.
Flying high on the FX Nytro XTX.
TEC IDEAS - These hand-warmers on the Renegade are now the best in the biz.
We like the grab bar, a necessity on a crossover sled.
There's also plenty of room for a turbo under the hood, but the secondary is hard to remove, and it's not super-easy to change the clutching.
FIRST TRACKS - We were able to go nearly anywhere off-trail with this Renegade, and the rear end felt incredibly light for a big 4-stroke.
The Renegade is a fun sled to toss around and catch some air.
What we've seen in the last 3 years is a proliferation in the 4-stroke market.
While some Ski-Doo 2-stroke guys tell you demand for 4-strokes is dwindling and you won't see much growth there, Yamaha's 4-stroke guys say they've grown to be the No. 2 OEM simply on 4-stroke sales. In 2009, both are investing heavily in 4-strokes.
Yamaha and Ski-Doo are giving buyers more of what they want with long-track versions of their 130-hp 4-strokers. Enter the Nytro XTX and MXZ Renegade X 1200.
Yamaha goes long
It was expected that Yamaha would come with a long-track Nytro for '09, but few would have guessed the new Nytro XTX to be a full 144-in. long rendition.
As we've said many times, WE LOVE THIS ENGINE! The 1049cc, 3-cylinder, liquid 4-stroke was dynoed by Tech Editor Olav Aaen to have 138.6 hp at 8,500 rpm. So why not let it churn a 144-in. RipSaw track around a 6-degree tipped up rail?
This engine actually seems more at home with this application than the short-track version.
The Mikuni-carbed FI engine gets good gas mileage - 15.3 mpg in our Real World test - is reliable, runs on 87 octane, after its first break-in oil change it only needs to be changed every 2,500 miles, and it has an easy electric start.
In addition to the torquey engine, XTX also gets all new Nytro front-end updates AND a bump-straddling, torque-harnessing, 1.25-in. lugged, 15-in.-wide track. The fully coupled dual shock CK 144 rear suspension has a three-setting pre-load cam-type adjuster on the torsion springs so you can easily set ride height and stiffness to your liking. Also, coupling adjustments can be made via a turn of the collar on the control rods in back. You'll also get a remote reservoir adjustable clicker rear shock with 12 compression clicks.
Taking a cue from its mountain sled testers and snocrossers, Yamaha's XTX has big snow evacuation holes in the boards and a steeper running-board angle of 11 degrees vs. the former Nytro's 9 degrees. Yamaha also made significant changes to the front end of all its Nytro-based sleds. To make the sled more stable, the castor angle was increased from a more up and down 22 degrees to a relaxed 25.8 degrees. The trail at the ski bottom was increased here from 21.4mm to 42.5mm and a revised spindle and shorter A-arms were used to accommodate the castor angle change.
Camber also was increased and ski stance narrowed. You get GYTR dual-
clicker front shocks too, with 12 clicks of compression damping adjustment and 20 clicks of rebound damping adjustment. Talking with Yamaha engineers, they have experimented with slightly more "toe-out" on their '09 sleds. This was something we also worked on with our 2008 demo sled.
Initial hits
The engine, of course.
Tipped up rail. We liked it in the old Polaris Switchbacks too, but "market research" told Polaris that everyone wanted a 136-incher. We're glad Yamaha brought it back! Why sacrifice a shorter track when you can get all the on-trail benefits of a 121 and still have big bump-bridging capability and off-trail dominance? We'll see how this plays out, but I have a feeling this 144-inch Nytro XTX is going to steal sales from a lot of those 136-inchers.
Front end. We like the changes here and believe about 30-40% of the Nytro's darting and unpredictability in the corners has been dialed out. It corners flatter and there isn't as much nervousness in the bumps as last year's short-track.
Rear end. We also like being able to change coupling settings because last year there were NOT adjustable blocks on the Nytros. However, the XTX's couplers aren't as easy to change as some on other sleds.
Top speed. In initial speed runs, this thing has better top end than even some of its short-track brethren. On long open sweeping trails it will not give up anything to an 800 and seems to pull harder than any 700 from the last 3 years.
Running boards. Snow removal is much better with the big "slash" holes and the boards are easy to get a grip on.
Initial pits
Cold. This is inherent to the Nytro body style, the XTX is a cold ride. Even with the slightly larger windshield for this year, the Nytro isn't warm. There needs to be more heat in the handgrips too. Wattage needs to be increased to the bars ASAP if you want to ride XTX in temps less than 25 F.
Handlebar action. Nytro-based sleds are difficult, especially for smaller riders, to leverage in hard aggressive turns. Because the bars move in a more vertical action, riders actually end up pulling them into their crotch while the other end of the bar is high and away from one's body. Don't ask us how Steve Taylor does it for Team Yamaha on the snocross track.
Front-end dive. We noticed this last year on our Nytro, and it could partially be due to engine braking and suspension set-up, but after trying many adjustments, we think it might also simply be due to the sled's geometry. We noticed that every time we hit a big bump head on, the front end would basically dive into the bump unless we were heavily on the gas. While looking at our Nytro XTX photos, we noticed the front end kicked up a lot more snow than any other machine. If you are a snocross fan, we saw this on the race sled as well. Every time Steve Taylor hit a bump before take-off there was an explosion of snow around the front shocks.
No mountain grab bar. If you are going to have a 144-in. crossover sled that is a big 4-stroke, you should have a grab bar in the middle of the handlebars.
No storage. Saddlebags are your only option here.
2009 Yamaha XTX
Engine: 1049cc liquid triple 4-stroke
HP: 138.6 (AmSnow tested)
Exhaust: 2-valves, 3-1 rear exhaust
Ski Stance: 41.3 in.
Front Susp.: Next generation FX-style independent, double wishbone
Rear Susp.: Dual Shock CK 144-inch
Track: 15x144x1.25 in.
Fuel Tank: 7.4 gal.
Price: $10,549 US
Ski-Doo is all new
The yellow camp couldn't deny that there are buyers who simply want a 4-stroke, so Ski-Doo gave consumers a new high-performance, 130-hp 4-stroke, the 1200 4-TEC.
This 1170.7cc, dual-overhead cam, inline, 3-cylinder engine is available in models across Ski-Doo's line, but for this comparison we were interested in the 4-TEC powered MXZ Renegade X 1200.
The 137-in. long Renegade is built for crossover performance. The 1.25-in. lugged track is 16 inches wide so there's a big footprint for off-trail flotation.
Since this Renegade has the 4-stroke engine, it comes in the new REV/XR body, which has a wider hood and slightly different aesthetics than the REV/XP chassis. Several changes were made to the original XP chassis in order to house the larger 4-stroke mill, which brings the Renegade's dry weight to a Ski-Doo estimated 521 lbs.
One of the first things you'll notice on this sled is the low engagement speed of 2,800 rpm. It's sneaky fast on the draw, and if you just mash the throttle out of the gate, it won't even feel like you've started moving until you're suddenly cruising down the trail.The big 4-stroke engine winds out at a low 7,750 rpm too.
Initial hits
Shock calibration. The smoothness of the X-package prototype 1200 shock calibration was perfect. While this is an X-sled, it cycled through its suspension with plush initial stroke and also great bottoming resistance. Extra oil in the piggyback shocks kept them from fading as we got into the bigger bumps and pushed hard through the ripple bumps.
While we don't suggest trying this at home, we watched snocross rider Willie Elam do half a dozen whip-jumps off a natural ramp in Colorado, and the big 4-stroke took the landings well. Even Elam commented on the set-up. The Kayaba HPG clicker take-apart aluminum front shocks are easy to adjust and so is the racing clicker on the rear arm. An HPG take-apart aluminum shock also sits in the front arm.
Smoothness. Clutch engagement, throttle pull, exhaust tone and just about everything on this sled, from a performance standpoint was smooth. Cornering was impressive, but not quite up to the level of the 2-stroke XPs. We believe the small bit of tippiness we felt was due to a slightly taller vehicle height than the XP sleds (3.5 in. taller) and the heavier engine. The best "smoothness" feature of the 1200 was how easy the mechanical reverse was to shift. This is possibly the fastest forward to reverse and vice-versa system out there.
Top end. For only 130 horses, this sled hung right with the 700, 800 and larger straight 4-stroke sleds on the top end. It was not nearly as fast as some sleds out of the hole, but top-end speed was great.
Tank size. With a 10.6-gal. tank and at a Ski-Doo estimated 18.3 mpg, this sled's range should be more than 190 miles. We love not filling tanks every 60 miles, wasting time gassing up.
Initial pits
Brakes. The brakes felt mushy to everyone that rode the Renegade. It's very easy on this sled to build up speed because of the small amount of engine noise and with its long legs, a rider could conceivably get in trouble quickly without a super braking system. The brake set-up on the 1200 Renegade was mediocre.
Engine Braking. Much of the engine braking was dialed out from the first to the second pre-production rides, but many of our riders still felt there was too much. Personally, I like a little engine braking as it helps set you up for the next corner. Too much and the front end dives, especially in loose snow, too little and you are constantly on the brake. Ski-Doo is close to the right amount of engine braking, but as of our last ride, still wasn't quite there.
Rubber Band Syndrome. At press time this was being corrected, but due to a low initial engagement speed and extremely smooth shift-out, it sometimes felt like this sled was on a rubber band. That made it difficult at times to drive aggressively in the low-midrange of the powerband.
No storage! Just about anyone would sacrifice 2-3 lbs. to have a little trunk.
Final thoughts
Ski-Doo's Renegade 1200 is best suited for longer days as it takes less effort to ride than the Yamaha XTX. Yamaha has come a long way in figuring out the Nytro's front-end and we like the 144-in. track. You've really got to drive any Nytro-based sled, as the harder you push it, the better it will handle. If Ski-Doo can get the clutching dialed in on the 1200, it will possibly be the best first-year 4-stroke to date.
Basically, if you want a tougher sounding sled, with better off-trail capability, more initial burst from the engine and a sportier look, then the Yamaha XTX is your sled. If you want a sled that can rip up the powder AND still be an extremely comfortable long-mileage machine, go for the Renegade 1200X.
2009 Ski-Doo Renegade X 1200 4-TEC
Engine: 1170.7cc Rotax liquid triple DOHC 4-stroke
HP: 130 (S.D. claimed)
Exhaust: Single-head pipe, baffle muffler
Ski Stance: 47 in.
Front Susp.: Dual A-arm with T-A alum. Kayaba HPG clicker shocks
Rear Susp.: SC-5 w/T-A alum. Kayaba HPG front-arm shock and T-A alum. Kayaba HPG racing clicker rear-arm shock
Track: 16x137x1.25 in.
Fuel Tank: 10.6 gal.
Price: $11,299 US
Odds & Ends
Yamaha: The "trail" of their ski is larger
This means that the distance between the contact area of the ski and imaginary contact point of the steering axis with the ground was increased. More trail tends to mean more stability, while less makes for more positive steering.
Ski-Doo: Good on gas
The 4-TEC 1200 engine runs best on regular 87-octane fuel. OEM estimates show it getting 18.3 mpg/22 kpg too!
DRY WEIGHT VS. WET WEIGHT, WE DO THE MATH -
The Ski-Doo MXZ X Renegade 1200 weighs 521 lbs. dry and has a 10.6-gal. fuel tank. The Yamaha Nytro XTX weighs 542 lbs. dry and has a 7.4-gal. tank. If a standard U.S. gallon of unleaded gas weighs about 6.5 lbs. at riding temps (gas is more dense in cold temps), simply computing the wet weights after filling sleds with gas, these two would be almost exactly the same weight (less than a pound difference). So, after adding oil, antifreeze, brake fluid, grease and all the other little nuances, these sleds should be within pounds of each other when totally wet. We'll do our own wet weight tests later this season and find out!
Mark Savage
Second opinion
Nytro vs. Renegade - This tale of two crossovers boils down to engine vs. handling. Nytro's engine is a monster with great low-end pop, which makes it a hoot. But Nytro's handling, while improved from last season, doesn't match the Renegade's. Yet, the Renegade's engine, while good mid- to top-end, lacks pop off-the-line. Which do you want, hole shot or handling? On a long ride, I'd choose handling!
Mark Savage, Editor
http://www.bergstromskegs.com/oui/still ... e_past.htm
I was able to find a copy of it here on TY. http://www.ty4stroke.com/viewtopic.php? ... b5ac29dc17
I marked the front end sections in bold.
TECH TESTS HOW-TO PRODUCTS
WELCOME to the NEW AMSNOW.com! Check out our latest additions - CLICK HERE
Comparison Test: Four play!
Ski-Doo takes on Yamaha in the 130-horse 4-stroke crossover market
Mark Boncher
8/18/2008
4-STROKE FEVER - We tested all the new 2009 crossover and high-performance 130-horse 4-strokes from Ski-Doo and Yamaha last spring on the same day. We ran them through big bumps, powder, tight trails and more! Kort Duce photos
CARVE THE TURKEY - The easy carving and deep snow side-hilling ability of the XTX is impressive and predictable. Let's just hope snow/ice doesn't still build up under the tunnel.
NYTRO UPGRADES - There now are big snow removal slashes in the running boards.
The mechanical reverse lever still annoys us.
Adjustable couplers on the rear skid plus shorter front A-arms help handling.
Flying high on the FX Nytro XTX.
TEC IDEAS - These hand-warmers on the Renegade are now the best in the biz.
We like the grab bar, a necessity on a crossover sled.
There's also plenty of room for a turbo under the hood, but the secondary is hard to remove, and it's not super-easy to change the clutching.
FIRST TRACKS - We were able to go nearly anywhere off-trail with this Renegade, and the rear end felt incredibly light for a big 4-stroke.
The Renegade is a fun sled to toss around and catch some air.
What we've seen in the last 3 years is a proliferation in the 4-stroke market.
While some Ski-Doo 2-stroke guys tell you demand for 4-strokes is dwindling and you won't see much growth there, Yamaha's 4-stroke guys say they've grown to be the No. 2 OEM simply on 4-stroke sales. In 2009, both are investing heavily in 4-strokes.
Yamaha and Ski-Doo are giving buyers more of what they want with long-track versions of their 130-hp 4-strokers. Enter the Nytro XTX and MXZ Renegade X 1200.
Yamaha goes long
It was expected that Yamaha would come with a long-track Nytro for '09, but few would have guessed the new Nytro XTX to be a full 144-in. long rendition.
As we've said many times, WE LOVE THIS ENGINE! The 1049cc, 3-cylinder, liquid 4-stroke was dynoed by Tech Editor Olav Aaen to have 138.6 hp at 8,500 rpm. So why not let it churn a 144-in. RipSaw track around a 6-degree tipped up rail?
This engine actually seems more at home with this application than the short-track version.
The Mikuni-carbed FI engine gets good gas mileage - 15.3 mpg in our Real World test - is reliable, runs on 87 octane, after its first break-in oil change it only needs to be changed every 2,500 miles, and it has an easy electric start.
In addition to the torquey engine, XTX also gets all new Nytro front-end updates AND a bump-straddling, torque-harnessing, 1.25-in. lugged, 15-in.-wide track. The fully coupled dual shock CK 144 rear suspension has a three-setting pre-load cam-type adjuster on the torsion springs so you can easily set ride height and stiffness to your liking. Also, coupling adjustments can be made via a turn of the collar on the control rods in back. You'll also get a remote reservoir adjustable clicker rear shock with 12 compression clicks.
Taking a cue from its mountain sled testers and snocrossers, Yamaha's XTX has big snow evacuation holes in the boards and a steeper running-board angle of 11 degrees vs. the former Nytro's 9 degrees. Yamaha also made significant changes to the front end of all its Nytro-based sleds. To make the sled more stable, the castor angle was increased from a more up and down 22 degrees to a relaxed 25.8 degrees. The trail at the ski bottom was increased here from 21.4mm to 42.5mm and a revised spindle and shorter A-arms were used to accommodate the castor angle change.
Camber also was increased and ski stance narrowed. You get GYTR dual-
clicker front shocks too, with 12 clicks of compression damping adjustment and 20 clicks of rebound damping adjustment. Talking with Yamaha engineers, they have experimented with slightly more "toe-out" on their '09 sleds. This was something we also worked on with our 2008 demo sled.
Initial hits
The engine, of course.
Tipped up rail. We liked it in the old Polaris Switchbacks too, but "market research" told Polaris that everyone wanted a 136-incher. We're glad Yamaha brought it back! Why sacrifice a shorter track when you can get all the on-trail benefits of a 121 and still have big bump-bridging capability and off-trail dominance? We'll see how this plays out, but I have a feeling this 144-inch Nytro XTX is going to steal sales from a lot of those 136-inchers.
Front end. We like the changes here and believe about 30-40% of the Nytro's darting and unpredictability in the corners has been dialed out. It corners flatter and there isn't as much nervousness in the bumps as last year's short-track.
Rear end. We also like being able to change coupling settings because last year there were NOT adjustable blocks on the Nytros. However, the XTX's couplers aren't as easy to change as some on other sleds.
Top speed. In initial speed runs, this thing has better top end than even some of its short-track brethren. On long open sweeping trails it will not give up anything to an 800 and seems to pull harder than any 700 from the last 3 years.
Running boards. Snow removal is much better with the big "slash" holes and the boards are easy to get a grip on.
Initial pits
Cold. This is inherent to the Nytro body style, the XTX is a cold ride. Even with the slightly larger windshield for this year, the Nytro isn't warm. There needs to be more heat in the handgrips too. Wattage needs to be increased to the bars ASAP if you want to ride XTX in temps less than 25 F.
Handlebar action. Nytro-based sleds are difficult, especially for smaller riders, to leverage in hard aggressive turns. Because the bars move in a more vertical action, riders actually end up pulling them into their crotch while the other end of the bar is high and away from one's body. Don't ask us how Steve Taylor does it for Team Yamaha on the snocross track.
Front-end dive. We noticed this last year on our Nytro, and it could partially be due to engine braking and suspension set-up, but after trying many adjustments, we think it might also simply be due to the sled's geometry. We noticed that every time we hit a big bump head on, the front end would basically dive into the bump unless we were heavily on the gas. While looking at our Nytro XTX photos, we noticed the front end kicked up a lot more snow than any other machine. If you are a snocross fan, we saw this on the race sled as well. Every time Steve Taylor hit a bump before take-off there was an explosion of snow around the front shocks.
No mountain grab bar. If you are going to have a 144-in. crossover sled that is a big 4-stroke, you should have a grab bar in the middle of the handlebars.
No storage. Saddlebags are your only option here.
2009 Yamaha XTX
Engine: 1049cc liquid triple 4-stroke
HP: 138.6 (AmSnow tested)
Exhaust: 2-valves, 3-1 rear exhaust
Ski Stance: 41.3 in.
Front Susp.: Next generation FX-style independent, double wishbone
Rear Susp.: Dual Shock CK 144-inch
Track: 15x144x1.25 in.
Fuel Tank: 7.4 gal.
Price: $10,549 US
Ski-Doo is all new
The yellow camp couldn't deny that there are buyers who simply want a 4-stroke, so Ski-Doo gave consumers a new high-performance, 130-hp 4-stroke, the 1200 4-TEC.
This 1170.7cc, dual-overhead cam, inline, 3-cylinder engine is available in models across Ski-Doo's line, but for this comparison we were interested in the 4-TEC powered MXZ Renegade X 1200.
The 137-in. long Renegade is built for crossover performance. The 1.25-in. lugged track is 16 inches wide so there's a big footprint for off-trail flotation.
Since this Renegade has the 4-stroke engine, it comes in the new REV/XR body, which has a wider hood and slightly different aesthetics than the REV/XP chassis. Several changes were made to the original XP chassis in order to house the larger 4-stroke mill, which brings the Renegade's dry weight to a Ski-Doo estimated 521 lbs.
One of the first things you'll notice on this sled is the low engagement speed of 2,800 rpm. It's sneaky fast on the draw, and if you just mash the throttle out of the gate, it won't even feel like you've started moving until you're suddenly cruising down the trail.The big 4-stroke engine winds out at a low 7,750 rpm too.
Initial hits
Shock calibration. The smoothness of the X-package prototype 1200 shock calibration was perfect. While this is an X-sled, it cycled through its suspension with plush initial stroke and also great bottoming resistance. Extra oil in the piggyback shocks kept them from fading as we got into the bigger bumps and pushed hard through the ripple bumps.
While we don't suggest trying this at home, we watched snocross rider Willie Elam do half a dozen whip-jumps off a natural ramp in Colorado, and the big 4-stroke took the landings well. Even Elam commented on the set-up. The Kayaba HPG clicker take-apart aluminum front shocks are easy to adjust and so is the racing clicker on the rear arm. An HPG take-apart aluminum shock also sits in the front arm.
Smoothness. Clutch engagement, throttle pull, exhaust tone and just about everything on this sled, from a performance standpoint was smooth. Cornering was impressive, but not quite up to the level of the 2-stroke XPs. We believe the small bit of tippiness we felt was due to a slightly taller vehicle height than the XP sleds (3.5 in. taller) and the heavier engine. The best "smoothness" feature of the 1200 was how easy the mechanical reverse was to shift. This is possibly the fastest forward to reverse and vice-versa system out there.
Top end. For only 130 horses, this sled hung right with the 700, 800 and larger straight 4-stroke sleds on the top end. It was not nearly as fast as some sleds out of the hole, but top-end speed was great.
Tank size. With a 10.6-gal. tank and at a Ski-Doo estimated 18.3 mpg, this sled's range should be more than 190 miles. We love not filling tanks every 60 miles, wasting time gassing up.
Initial pits
Brakes. The brakes felt mushy to everyone that rode the Renegade. It's very easy on this sled to build up speed because of the small amount of engine noise and with its long legs, a rider could conceivably get in trouble quickly without a super braking system. The brake set-up on the 1200 Renegade was mediocre.
Engine Braking. Much of the engine braking was dialed out from the first to the second pre-production rides, but many of our riders still felt there was too much. Personally, I like a little engine braking as it helps set you up for the next corner. Too much and the front end dives, especially in loose snow, too little and you are constantly on the brake. Ski-Doo is close to the right amount of engine braking, but as of our last ride, still wasn't quite there.
Rubber Band Syndrome. At press time this was being corrected, but due to a low initial engagement speed and extremely smooth shift-out, it sometimes felt like this sled was on a rubber band. That made it difficult at times to drive aggressively in the low-midrange of the powerband.
No storage! Just about anyone would sacrifice 2-3 lbs. to have a little trunk.
Final thoughts
Ski-Doo's Renegade 1200 is best suited for longer days as it takes less effort to ride than the Yamaha XTX. Yamaha has come a long way in figuring out the Nytro's front-end and we like the 144-in. track. You've really got to drive any Nytro-based sled, as the harder you push it, the better it will handle. If Ski-Doo can get the clutching dialed in on the 1200, it will possibly be the best first-year 4-stroke to date.
Basically, if you want a tougher sounding sled, with better off-trail capability, more initial burst from the engine and a sportier look, then the Yamaha XTX is your sled. If you want a sled that can rip up the powder AND still be an extremely comfortable long-mileage machine, go for the Renegade 1200X.
2009 Ski-Doo Renegade X 1200 4-TEC
Engine: 1170.7cc Rotax liquid triple DOHC 4-stroke
HP: 130 (S.D. claimed)
Exhaust: Single-head pipe, baffle muffler
Ski Stance: 47 in.
Front Susp.: Dual A-arm with T-A alum. Kayaba HPG clicker shocks
Rear Susp.: SC-5 w/T-A alum. Kayaba HPG front-arm shock and T-A alum. Kayaba HPG racing clicker rear-arm shock
Track: 16x137x1.25 in.
Fuel Tank: 10.6 gal.
Price: $11,299 US
Odds & Ends
Yamaha: The "trail" of their ski is larger
This means that the distance between the contact area of the ski and imaginary contact point of the steering axis with the ground was increased. More trail tends to mean more stability, while less makes for more positive steering.
Ski-Doo: Good on gas
The 4-TEC 1200 engine runs best on regular 87-octane fuel. OEM estimates show it getting 18.3 mpg/22 kpg too!
DRY WEIGHT VS. WET WEIGHT, WE DO THE MATH -
The Ski-Doo MXZ X Renegade 1200 weighs 521 lbs. dry and has a 10.6-gal. fuel tank. The Yamaha Nytro XTX weighs 542 lbs. dry and has a 7.4-gal. tank. If a standard U.S. gallon of unleaded gas weighs about 6.5 lbs. at riding temps (gas is more dense in cold temps), simply computing the wet weights after filling sleds with gas, these two would be almost exactly the same weight (less than a pound difference). So, after adding oil, antifreeze, brake fluid, grease and all the other little nuances, these sleds should be within pounds of each other when totally wet. We'll do our own wet weight tests later this season and find out!
Mark Savage
Second opinion
Nytro vs. Renegade - This tale of two crossovers boils down to engine vs. handling. Nytro's engine is a monster with great low-end pop, which makes it a hoot. But Nytro's handling, while improved from last season, doesn't match the Renegade's. Yet, the Renegade's engine, while good mid- to top-end, lacks pop off-the-line. Which do you want, hole shot or handling? On a long ride, I'd choose handling!
Mark Savage, Editor
arteeex
TY 4 Stroke Master
AKrider said:
The tie rod cannot be parallel to the lower a-arms in more than one specific location because it is not the same length and the pivot axis is not co-plannar - in the dimension of interest. This is true for the upper a-arm as well. The compromise is made in deciding where the in the range of motion of the system this discrepancy is going to be minimized or best tolerated.
Anyway, when it's moving are both skis ever on the ground at the same time with the Nytro?
nytrolovin
Veteran
zbroz front end
Great thread but all the technical suspension theory I admit is over my head. We all just want our nytros to handle better no? I too have crapped my pants on the trail many times on my 08. To keep from soiling myself I installed a zbroz 42 inch front end kit with the update kit that has the increased caster. I am running stock nytro fox x shocks, slydog trail skis and 6 inch dually carbides. I had limited ride time but this is what I experienced; no darting, slightly easier steering and much improved high speed handling, keeping in mind that I am running a supercharger(love it). However, I found that the sled would push and slide through corners so it seemed like one extreme to the other. I am wondering about getting the castor back out or changing out the skis again. I am also running an fast airwave rear suspension. So I am not going to make a final judgement until some more ride time next year.
Great thread but all the technical suspension theory I admit is over my head. We all just want our nytros to handle better no? I too have crapped my pants on the trail many times on my 08. To keep from soiling myself I installed a zbroz 42 inch front end kit with the update kit that has the increased caster. I am running stock nytro fox x shocks, slydog trail skis and 6 inch dually carbides. I had limited ride time but this is what I experienced; no darting, slightly easier steering and much improved high speed handling, keeping in mind that I am running a supercharger(love it). However, I found that the sled would push and slide through corners so it seemed like one extreme to the other. I am wondering about getting the castor back out or changing out the skis again. I am also running an fast airwave rear suspension. So I am not going to make a final judgement until some more ride time next year.
Got so carried away with thinking the tie rod needed to be parallel to the lower a-arm I forgot all about instant center. So, figuring that Yamaha built that in seeing as how the two a-arms and tie rod are all at different angles should be a simple matter of spacing the end of the tie rod up and down to the sweet spot.
Conclusion.... I give up. My Phazer tie rod end had too much slop so I ground off the collars on my stock tie rod end and shimmed it up and down. I also constructed a new rig with the laser level using a mirror, pretty much like the guy did in the video. The best I could get out of my front end was a total of 5 mm of toe change on one ski. Figure that would be 10 mm for both skis which is a tick over 3/8". I was looking for 1/16" total toe change. The bad thing is the ski first toed out and then back in. I simply could not tune that out.
About the only thing I accomplished was finding the 2.5 mm ball joint mod made the toe out worse at the first part of the stroke. I switched back to the stock upper ball joint and saw improved toe control.
I hate to admit it but I'm pretty convinced my racing buddy is right. It is a total waste of time and effort to try and do anything to improve the stock Nytro front end. Since the '09 geometry is only 30%-40% better than absolute garbage... in the end what do you have? A really nice engine wrapped in a POS chassis.
I'll reserve judgement on the aftermarket front ends that are on the market until I ride them or see convincing documentation that they work. Thanks to everyone for working together and brainstorming ideas. That was fun!
Conclusion.... I give up.
My Phazer tie rod end had too much slop so I ground off the collars on my stock tie rod end and shimmed it up and down. I also constructed a new rig with the laser level using a mirror, pretty much like the guy did in the video. The best I could get out of my front end was a total of 5 mm of toe change on one ski. Figure that would be 10 mm for both skis which is a tick over 3/8". I was looking for 1/16" total toe change. The bad thing is the ski first toed out and then back in. I simply could not tune that out.About the only thing I accomplished was finding the 2.5 mm ball joint mod made the toe out worse at the first part of the stroke. I switched back to the stock upper ball joint and saw improved toe control.
I hate to admit it but I'm pretty convinced my racing buddy is right. It is a total waste of time and effort to try and do anything to improve the stock Nytro front end. Since the '09 geometry is only 30%-40% better than absolute garbage... in the end what do you have? A really nice engine wrapped in a POS chassis.
I'll reserve judgement on the aftermarket front ends that are on the market until I ride them or see convincing documentation that they work. Thanks to everyone for working together and brainstorming ideas. That was fun!
