Viper glider build

[yamakazie]

I can't compare, only comment. I never tried the stock Tuner skis and these are my 1st set of Curves with my 1st set of Slim Jim's on a sled I only started riding this year. Everything is new to me. All I can say is I have no complaints on the combination.

 

[grizztracks]

I'm not sure what's the difference in drivers are on a Nytro RTX and Viper RTX but it sounds like the Viper uses a bigger drive sprocket. I don't believe there's any way to re-calibrate the Nytro system without accessing the ECU. Maybe we can fabricate a new pickup gear and get the speedometer a little closer. We'll need to look at this in the off season.

If you really are hitting 105 mph I'd say that your Viper with the Nytro electronics is running better than the stock Viper. I have a similar clutch setup and only hit 97-98 on my trip up North.

I'm also running the Curves but with the 6" Accord Magnum bars. I had a lot of darting last season with them so I shimmed the rubbers and it corrected the issue. Since then Curve came out with new rubbers to help correct the darting issue. They sent me a set but I haven't installed them yet. From the looks of the higher backed rubbers they should eliminate the need for the shims.

 

[yamakazie]

Miscalculation, it's a 16% difference on the speedometer. You would think I could handle this with an engineering degree. Must have been the fumes. Anyway, Grizz n I are discussing corrections in the off season (which appears to have started already). One option is to machine a new size gear for the end of the driveshaft. Another is to somehow reprogram the calibration in the computer. I wonder if Evolution Powersports or a dealer can do this?

 

[Hawwwtcoffee]

I have the c&a rz with the slim jim doolys and love them. Had absolutely no luck in perfecting the tuner 2 ski with various carbides stock 2&4 and 4&6 / 6&8 inch woodys. I just found my self in all types of snow steering way before a corner and chopping throttle half way to get them to bite. Adjusted Center shock as well. I run the woodys double digger in a tight and wide V variation. Hope this helps. I did find this season my speedo is way off ha I could only hit 112kmh and my buddies both on 600 doos on the lake were never close by...found out they were ranging between 140-155 and I never made it past 112...very odd but hey if I'm smiling at the end of the lake and docking less miles on my od that's a win win for me.


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[Mills]

So is it your opinion that it is the ECU that is the difference between the power of a Nytro vs. a Viper? If so, can the fuel/timing and other engine management data from a Nytro/Yamaha ECU be captured and dumped into a Viper/Cat ECU to make the engine run like a Nytro would? Has Evo or any other development company done this? I just bought a brand new 2014 Viper in favor of my '08 Nytro for ride comfort reasons but, I really don't want to lose the HP/Torque of my Nytro.

 

[cannondale27]

So is it your opinion that it is the ECU that is the difference between the power of a Nytro vs. a Viper? If so, can the fuel/timing and other engine management data from a Nytro/Yamaha ECU be captured and dumped into a Viper/Cat ECU to make the engine run like a Nytro would? Has Evo or any other development company done this? I just bought a brand new 2014 Viper in favor of my '08 Nytro for ride comfort reasons but, I really don't want to lose the HP/Torque of my Nytro.

Rest easy. Real world I don't see any difference other than "feel" A nitro really squats and hooks up. Lower seating and handlebars on Nytro make it feel like you are falling off the thing. I believe that gives it the feel of being faster. Once your Viper is setup equally there isn't going to be any EQUAL Nytros blowing you away. A viper hides its speed because it handles so well and the Speedo is accurate so it just seems slower. Maybe a little clutching but that's about all that's needed to run with a Nytro. You get into rough conditions and you will beat a Nytro. Been there and done that. Was easy peasy and that was a XTX Nytro with a Turbo. I smoked him 3 of 3. Why because he could not put the power to the snow and once he did he could not run through the rough like I was. Just remember apples to apples and oranges to oranges. Nytros have been out a long time and most are not stock. So mod your Viper equally if racing a modded one.

 

[yamakazie]

A little over a year ago Grizz n I were waiting for some friends at an intersection. I was on the Nytro and he had his stock 2015 Viper. After asking me a few times and against my better judgement, I took his Viper for a 2 mile test spin. I first took it across a field then down a tight woods trail with some bumps. I noticed in the field the engine felt flatter than my Nytro. What sold me on the Viper was the trip through the woods. I couldn't believe how much better it was through the bumps and handled in the corners, especially the chopped up corners. Way less fatiguing than my Nytro. It was that moment when I knew I needed a Viper. Which brings us to start of this thread.

Back to the point of this topic, I felt the engines were noticeably different. Unfortunately this year's lack of snow didn't bring our two Viper's together. I would've loved to run them side by side then switch seats and run them again. I feel like the Viper we built in this thread runs the same as my old Nytro. I have a Nytro engine with Nytro ECU in an otherwise stock Viper. In my mind this proves the power loss in the stock machine is the Cat ECU.

 

[grizztracks]

I disagree cannondale27 , my Nytro RTX top speed is approximately equal to my Viper RTX but the Nytro pulls a lot harder. Both models may have similar HP numbers but the Nytro seems to have much better low/mid range torque than the Viper. There is a noticeable difference and so far with comparable clutching changes the Viper seems to lack torque. Like many have suggested this could be a directly related to exhaust and air intake but from what I know so far I'm leaning toward ECU differences. I do agree the Viper is superior when it comes to handling and ride but after talking to yamakazi he says his hybrid Viper feels comparable to the Nytro donor sled as far as engine performance. Unfortunately he hasn't had much time on other Vipers but before this project he did ride mine and also thought it was lacking in comparison to the Nytro. We were hoping to do some testing between my Viper and his hybrid Viper but I injured my back on my first ride out this year which put me in the ER. I finally recovered enough to ride again but winter isn't cooperating so we haven't had a chance to do the comparison and it's looking like we'll have to wait until next season.

I don't believe the Nytro ECU programing can be dumped into the Viper's cat ECU due to differences in technologies. An ECU flash has limits on what parameters can be altered so the ability to make significant changes doesn't exist unless someone designs a new unit. I ran into this with my motorcycle but luckily an aftermarket ECU was available.

 

[cannondale27]

I disagree cannondale27 , my Nytro RTX top speed is approximately equal to my Viper RTX but the Nytro pulls a lot harder. Both models may have similar HP numbers but the Nytro seems to have much better low/mid range torque than the Viper. There is a noticeable difference and so far with comparable clutching changes the Viper seems to lack torque. Like many have suggested this could be a directly related to exhaust and air intake but from what I know so far I'm leaning toward ECU differences. I do agree the Viper is superior when it comes to handling and ride but after talking to yamakazi he says his hybrid Viper feels comparable to the Nytro donor sled as far as engine performance. Unfortunately he hasn't had much time on other Vipers but before this project he did ride mine and also thought it was lacking in comparison to the Nytro. We were hoping to do some testing between my Viper and his hybrid Viper but I injured my back on my first ride out this year which put me in the ER. I finally recovered enough to ride again but winter isn't cooperating so we haven't had a chance to do the comparison and it's looking like we'll have to wait until next season.

I don't believe the Nytro ECU programing can be dumped into the Viper's cat ECU due to differences in technologies. An ECU flash has limits on what parameters can be altered so the ability to make significant changes doesn't exist unless someone designs a new unit. I ran into this with my motorcycle but luckily an aftermarket ECU was available.

Ha don't disagree. Race. Or at least get some vids and GPS numbers. I am telling you that feel of a machine means nothing other than making a person think they are faster. Just my opinion and what I have seen. Don't get me wrong I would love to have Nytro wiring and ECU but not to make my Viper faster. Just more reliable.

 

[grizztracks]

Without a doubt we know which one is more reliable. At the start of this season we wanted to see how his Viper with the Nytro engine and ECU would match up to my Nytro and Viper but with another warm winter we didn't get a chance to do the testing we wanted. Maybe next season. If you followed this project from the beginning we didn't set out to prove or disprove anything. Yamakazie found a new 2015 chassis without an engine and used his 2009 Nytro as a donor sled which allowed him to upgrade to a much better handling and riding platform. The best part of this project was the fact that he was able to offset most of the cost of the Viper by parting out his Nytro while the rest of use spent thousands for a Viper with an inferior electrical system.

 

[Sevey]

We should 'crowd fund' you guys for a trip to Quebec so we can resolve this.
interested to see the outcome.

If it wasn't for Quebec I wouldn't have had much of a season.
Ms

 

[cannondale27]

Recently in the Viper forum the 2600 rpm hesitation was brought up. I agree it's there on a Viper and more so if modded without a tune but it's minor and not even noticeable when riding hard. Now I can distinctly remember my buddies piped nytro having a HUGE burble a bit higher than that. Much worse than the Viper has. Has this been corrected in later Nytros? I believe his was a 2010XTX. I am not knocking Nytro just trying to show that it also was not perfect. I have no doubt if I had the parts on hand I would also do just as you guys did and convert the Viper highly admire the job you did and it made sense. Just have questions and would like answers before someone even thinks about this conversion.

 

[grizztracks]

In an effort to correct the speedometer error I did some rough calculation after measuring the difference between the Viper and Nytro drivers. I'm getting around 7" diameter for the Nytro RTX and 7.75" for the Viper RTX (measurement taken while installed so if anyone can verify the two diameters let me know). If that is correct it looks like the Hybrid Viper which uses the Nytro's 15 tooth pickup gear and display calibration results in a 10% error. Yamakazie's total millage difference on his Canada trip when compared to the ski doo's he rode with was also approximately 10%. I think adding a few teeth to the pickup gear might correct the error.


Stock Nytro Calibration = 21.99"circumference/15 tooth gear = 1.47" per tooth traveled

Hybrid Viper = 24.35" circumference/15 tooth gear = 1.62" per tooth traveled

Correction:
Viper = 24.35"/16 tooth = 1.52"
Viper = 24.35"/17 tooth = 1.43"

I guess the best way to prove this is to fabricate a 17 tooth pickup gear to see if works.

 

[cannondale27]

In an effort to correct the speedometer error I did some rough calculation after measuring the difference between the Viper and Nytro drivers. I'm getting around 7" diameter for the Nytro RTX and 7.75" for the Viper RTX (measurement taken while installed so if anyone can verify the two diameters let me know). If that is correct it looks like the Hybrid Viper which uses the Nytro's 15 tooth pickup gear and display calibration results in a 10% error. Yamakazie's total millage difference on his Canada trip when compared to the ski doo's he rode with was also approximately 10%. I think adding a few teeth to the pickup gear might correct the error.


Stock Nytro Calibration = 21.99"circumference/15 tooth gear = 1.47" per tooth traveled

Hybrid Viper = 24.35" circumference/15 tooth gear = 1.62" per tooth traveled

Correction:
Viper = 24.35"/16 tooth = 1.52"
Viper = 24.35"/17 tooth = 1.43"

I guess the best way to prove this is to fabricate a 17 tooth pickup gear to see if works.

I get 24.818 for Viper Drivers

 

[grizztracks]

That puts the calculation for a 17 tooth pickup gear even closer to the target number of 1.47 for the Nytro calibration. That's if the Nytro circumference is correct.