How many have changed gearing on an n/a viper/7000?

[cannondale27]

I’m debating on trying the 24/50 set on my XTX se as gearing low and using OD works well on my Phazer (secondary swapped to modern style). I see a lot of people saying the Viper doesn’t like using Overdrive though. Only downside is the clutches heat up more on long sustained OD use on my Phazer but nothing horrible. Phazer is geared for 67 and pulls 73 (81/82 speedo) before RPMs climb above 11,500 which is showing a good 7-10% OD with no machining done. If I could get that much OD out of the Viper then 24/50 would get 98 @ 1.1 and 106/107 with OD. Since the best I’ve ever seen is 101 so it seems like a good match.

You are forgetting about the gear reduction in Phazer. Off top of head I believe at 12,200rpm which is rev limiter on Phazer the clutch is turning 8500rpm. On a Viper at 9200rpm the clutch is already turning 9200 rpm. Well above the 9000 rpm most CVT clutches are horribly losing efficiency.

 

[Turtle]

You are forgetting about the gear reduction in Phazer. Off top of head I believe at 12,200rpm which is rev limiter on Phazer the clutch is turning 8500rpm. On a Viper at 9200rpm the clutch is already turning 9200 rpm. Well above the 9000 rpm most CVT clutches are horribly losing efficiency.

Cannondale - I'll add something to your point about clutch efficiency. I've had stock gearing on my RTX from the get go. When it was NA, the best top speed I got out of it was around 102. But it took absolutely perfect conditions, engine running well above 9000rpm, and the clutch working at it's best to get there. Essentially, with the hp available on the NA engine, you needed all the stars in perfect alignment to hit 100+ on trail conditions.

Since adding the turbo, I've still left stock gearing. And with the MPI kit, it's dangerous to run above 8600rpm unless further fuel mapping and fuel delivery mods are made. I've seen 106 as a top speed, and I have all the hp in the world to run out of gear now. But I think that tells you something about clutch efficiency as I now have enough hp to push the clutching to perform at it's best. Before = 102mph at 9000+rpm .... After = 106mph at 8600rpm .... Essentially, the before didn't have enough hp to overcome the load and clutching necessary to get big top speed numbers. So the only way to get there was to spin everything faster (aka running higher rpm). At least that's how it makes sense to me.

 

[TD Max]

I've been playing with my clutching lately and ended up with pretty substantial underrev with revs climbing with speed. I found that I had pretty decent top speed considering my track with revs in the mid 8,000's climbing to maybe 8500-8700 at 86 mph. Need to do more work to match the secondary spring change that I started with.

 

[murdered141]

Cannondale - I'll add something to your point about clutch efficiency. I've had stock gearing on my RTX from the get go. When it was NA, the best top speed I got out of it was around 102. But it took absolutely perfect conditions, engine running well above 9000rpm, and the clutch working at it's best to get there. Essentially, with the hp available on the NA engine, you needed all the stars in perfect alignment to hit 100+ on trail conditions.

Since adding the turbo, I've still left stock gearing. And with the MPI kit, it's dangerous to run above 8600rpm unless further fuel mapping and fuel delivery mods are made. I've seen 106 as a top speed, and I have all the hp in the world to run out of gear now. But I think that tells you something about clutch efficiency as I now have enough hp to push the clutching to perform at it's best. Before = 102mph at 9000+rpm .... After = 106mph at 8600rpm .... Essentially, the before didn't have enough hp to overcome the load and clutching necessary to get big top speed numbers. So the only way to get there was to spin everything faster (aka running higher rpm). At least that's how it makes sense to me.

106 seems a bit low for turbo, but might be the limit for stock gearing without clutch machining, my ltx with stock 24-50 gears and machined clutches by Nos Pro got me 108 when NA and now a consistent 118 with mpi low boost turbo.

 

[Turtle]

106 seems a bit low for turbo, but might be the limit for stock gearing without clutch machining, my ltx with stock 24-50 gears and machined clutches by Nos Pro got me 108 when NA and now a consistent 118 with mpi low boost turbo.

I'm not machined for overdrive.

 

[Proangler]

Long time member first post, I have a 2014 xf7000 crosstour 141. I plan to do both gearing (24t 49b and 92p) and clutch, undecided which to do first. Currently on soft trail conditions 85 is top speed and 95 on well used groomed Trail. Looking to reduce normal driving rpms and increase top speed. I do 80% trail riding, but most trails contain mile long straights and very few tight twists. I love the low end grunt but was hoping for a little more. Any words of wisdom or help is appreciated. Seems this thread has tons of info but not much for outcomes from real world gearing changes. TIA

 

[Mark Seavey]

P

Long time member first post, I have a 2014 xf7000 crosstour 141. I plan to do both gearing (24t 49b and 92p) and clutch, undecided which to do first. Currently on soft trail conditions 85 is top speed and 95 on well used groomed Trail. Looking to reduce normal driving rpms and increase top speed. I do 80% trail riding, but most trails contain mile long straights and very few tight twists. I love the low end grunt but was hoping for a little more. Any words of wisdom or help is appreciated. Seems this thread has tons of info but not much for outcomes from real world gearing changes. TIA

Pro,

I have exact same sled and same year. Just did mine this fall and love it. Just changed top gear to the 24 T and left bottom gear and installed the new 92p chain. I see no different in low end and gained 5 mph on top. Another 1. 5 miles per gallon when cruising. I had same complaint as you. It’s worth doing. Check your tabs on your chain case, if original 2014 they are light duty and will crack. Mine had 6 crack taps that I only found because I was doing the chain and gears.

 

[Proangler]

Thanks @Mark Seavey, tabs are on list to check.
Have you done your clutch or running original setup which isn't too bad?

 

[blueironranger]

I put the RTX/LTX gear set (24/50) in my XTX and still reach the century mark mark without the revs climbing. Don’t really notice any more grunt on the trail, but it definitely has more Off-trail. This 1.6 cobra flat out sucks for traction under hard acceleration on trails, the lugs fold over.

 

[Mark Seavey]

Big difference in original and updated. Should have been a recall. But nope

Thanks @Mark Seavey, tabs are on list to check.
Have you done your clutch or running original setup which isn't too bad?

I changed the primary weights to 60 gram. I did that before the gear change because I was bumping the rev limiter at WOT on rail beds. So the weight change and 24t top gear change is spot on. Do yours up! U won’t be disappointed. When you do it also check the screws on the chain tension wheel. My back bolt was lose. I re installed

Thanks @Mark Seavey, tabs are on list to check.
Have you done your clutch or running original setup which isn't too bad?

 

[ViperRTX-Turbo009]

My viper (rtx le) with the hurricane 190 kit with 21/41 gears running a 1.5 ripsaw track.. I can hit 100 mph pretty much in any condition but only have a top speed of about 105 mph at about 9000 rpm. - clutches were sent to hurricane for machining and I'm running the gates 8dn equivalent. Im happy with the way the sled pulls - skis off the ground to 95 or so but after reading some of these comment I figure it should do better than 105 or so. What top speed should I be looking at realisically on the trail - (not ice as I'm sure on ice it would go faster) - more so just a good hard packed trail

Thanks

 

[Mitch Desorcy]

I run 22/41 gears and do 115 any time i want to. Have seen 122 on hard groomed trail. Hurricane turbo.

 

[Mark Seavey]

The sleds are a torque monster. So it’s what you want. Out of the box, (you might know if you had it before the turbo ) pulled hard to 75mph then seem to run out, then the other 10 to 15 mph was a slower climb. You now have added hp and clutching to have the hard pull to 105 mph. For my style of riding that would be what I want. But if you want more top end I would do a top gear change to 24 T and the 92 pitch chain. I don’t think you will notice any loss on the bottom. Mine is stock, and I made the gear change as I stated above an I do not notice any loss. But you will add 5 mph maybe 10mph. I was bumping 9000 rpm with the 60 gram weights. With the stock weights (57 gram)I was hitting rev limiter. With gear change and 60 gram weights I run 8800 rpm at WOT.



QUOTE="ViperRTX-Turbo009, post: 1427507, member: 23589"]My viper (rtx le) with the hurricane 190 kit with 21/41 gears running a 1.5 ripsaw track.. I can hit 100 mph pretty much in any condition but only have a top speed of about 105 mph at about 9000 rpm. - clutches were sent to hurricane for machining and I'm running the gates 8dn equivalent. Im happy with the way the sled pulls - skis off the ground to 95 or so but after reading some of these comment I figure it should do better than 105 or so. What top speed should I be looking at realisically on the trail - (not ice as I'm sure on ice it would go faster) - more so just a good hard packed trail

Thanks[/QUOTE]

 

[Janne339]

Is a 90 pitch chain too short för 24/49 gearing?

 

[NOS-PRO]

I'm 22/40 and my turbo Viper catwalks and see 120's anytime I want.....and that's with a 153" 2 1/4 track