'15 Viper RTX LE disappointment grows

[Zampinator]

O.K. bear with me a second here.......maybe I didn't pay attention in physics class (a distinct possibility but it has been a LOT of years).......in reading your comments I inferred that going to an 8 tooth driver (i.e. smaller diameter) would make the sled faster for a given gearing? That would seem (at least to my feeble old brain) to fly in the face of logic.........to wit: if the chaincase gearing stays the same, then there are less driver teeth engaging the track for a given number of revolutions of the driveshaft........hence slower track speed, not faster..........so what am I missing?

The small diameter (8 tooth) spins faster than the larger diameter (9 tooth). Yes? No? At least it does on dirt bikes! Lol

 

[500champ]

I got 94 mph on my 15 white and blue RTX LE , bone stock , 1.7 track , 8jp belt , something else has to be wrong

 

[buddah]

The small diameter (8 tooth) spins faster than the larger diameter (9 tooth)

HUH? A revolution of the driveshaft is a revolution of the driveshaft.........for a given engine rpm that will not change.........so please explain to me how a smaller diameter "wheel" (driver) can possibly spin faster than a larger one?????

 

[Zampinator]

I can, but this guy does it better.
Gear Ratios - Part 1: http://youtu.be/B4j2VPHVm6o

 

[Joey P]

It was bad enough when Yamaha snubbed us on the LE shock package with a bait and switch. Now those of us who have stuck with it are facing extremely disappointing top speed results.

My RTX LE hits the wall at mid 70's on the speedometer with 80 mph being the highest trail speed that I have seen. I have tried 2 different known clutching combinations with no major difference. I'm not the only one and I'm guessing that the only reason that the web is not a buzz over this is that many have not had snow to ride theirs.

I'm not throwing in the towel yet. The plan is to do a total clutch swap from a machine known to run past 100 mph with relative ease.

Yamaha may have snubbed me with zero response to my my well written letter documenting the shock fiasco, but they need to take notice before the crapstorm of angry owners hits...

P.S. Yamaha we have property in Hazelhurst and would gladly meet up with the guys from the northwoods testing facility some weekend.

wow befor mine was turboed i was seeing 95mph on my xtx

 

[Zampinator]

wow befor mine was turboed i was seeing 95mph on my xtx

How many miles did you have on your sled when you 95mph? any mods?

 

[kviper]

The small diameter (8 tooth) spins faster than the larger diameter (9 tooth). Yes? No? At least it does on dirt bikes! Lol

The problem is you need to compare the drive wheel size on the sled to the wheel of the motorcycle not the sproket. A smaller sprocket on the motorcycle with the same size wheel will result in more MPH. On the sled your talking about a smaller wheel.

 

[Motorboat]

I am on a 15 RTX SE and topped out at 83 on the trail and lake. 450 miles without any mods but it looks like there coming now.

 

[STAIN]

The gear in these Vipers is FAR too low in my opinion. Especially when the clutches don't go into overdrive. Name another production sled with a 2.08 gear? First thing I would do is go to a 1.85 to 1.95 gear. Eventually that 1.7 track will start to drag, I am guessing around 100mph or so.

 

[cannondale27]

Smaller drive sprocket (less teeth) using the same track pitch = slower top speed. Larger drive sprocket (more teeth) using the same track pitch = faster top speed.

If you changed your 9 tooth 2.86 pitch drivers (what the RTX & LTX models come with) to 8 tooth, you will lose top end speed.

Crap I had it backwards. Sorry. Cat 6000 XC which does use 8t 2:86 drivers has 23/40 gearing.

TD we will find something.

 

[Srxspec]

The gear in these Vipers is FAR too low in my opinion. Especially when the clutches don't go into overdrive. Name another production sled with a 2.08 gear? First thing I would do is go to a 1.85 to 1.95 gear. Eventually that 1.7 track will start to drag, I am guessing around 100mph or so.

You're comparing apples to oranges, you can not look just at the gear ratio itself. You must also look at the number of drive teeth on the drivers and the track pitch.

For example, an RX-1, Apex, FX Nytro, etc all have 9 tooth 2.52 pitch drivers. These drivers have a driver circumference of 22.68".

A RTX/LTX Viper has a 9 tooth 2.86 pitch driver. These drivers have a driver circumference of 25.74".

A XTX Viper has a 8 tooth 3.0 pitch driver. These drivers have a driver circumference of 24".

Driver circumference directly relates to the gear ratio. The larger the driver circumference is, the higher the MPH is. If you put 9 tooth 2.86 pitch drivers into a Apex (say a 2006 to 2010 121" model) with 24/38, that gearing with those drivers would gear an Apex to 134 mph (compared to 118 mph using the stock 9 tooth 2.52 drivers that come on an Apex).

 

[ViperBill]

Not sure on the gearing theory you would think if you were geared too low you would fully shift out and overrev. On ideal conditions i have seen 95mph 85 is more common but my rpm holds at 9100. Leads me to believe its a hp/drag problem. Gearing for more speed with same power would only cause the clutches to upshift less to hold same rpm.

 

[titanrcr]

Not sure on the gearing theory you would think if you were geared too low you would fully shift out and overrev. On ideal conditions i have seen 95mph 85 is more common but my rpm holds at 9100. Leads me to believe its a hp/drag problem. Gearing for more speed with same power would only cause the clutches to upshift less to hold same rpm.

That's a very fair statement, in fact most sleds are geared for more top end than they can reach.

 

[cannondale27]

You got it ViperBill. Is point I was trying to make this weekend. This is a true 90mph sled maybe a bit less under most conditions. We have HP but Torque is falling off badly. Torque does the work. HP gives you speed. Think 2stroke. Mine now is a bit more since mods but still only a true 95 mph sled and it cost me $ and work to get that. More will require many more times the work and more $. But dont forget our Speedos are accurate and if the right conditions triple digit speeds are definitly possible even stock. This sled is a real weapon in the right hands. Nothing to be ashamed of even at top end. But to get the edge everything has to be perfect and Mother Nature has to be smiling at you.

 

[titanrcr]

You got it ViperBill. Is point I was trying to make this weekend. This is a true 90mph sled maybe a bit less under most conditions. We have HP but Torque is falling off badly. Torque does the work. HP gives you speed. Think 2stroke. Mine now is a bit more since mods but still only a true 95 mph sled and it cost me $ and work to get that. More will require many more times the work and more $. But dont forget our Speedos are accurate and if the right conditions triple digit speeds are definitly possible even stock. This sled is a real weapon in the right hands. Nothing to be ashamed of even at top end. But to get the edge everything has to be perfect and Mother Nature has to be smiling at you.

Where is the torque falling off? It's a 130hp engine with a broad torque curve.