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

[cannondale27]

Stock viper and xf 7000 are a 21/49 that is a 2.33 ratio to 1. If you are running a 24/50 that is a 2.08 to 1. If you go to a 21/41 that will put you at 1.95 to 1. That will help your top end. I am not 2.04 to one and its where I want to be for what I do.

All stock Vipers are 24/50 gearing. They lowered the Cat gearing because the Cat clutch pulls overdrive easier than Yamaha so I heard. But looks like you have proved that wrong since gearing up helped you.

 

[Studroes144]

I have a ltx, I been told to try gearing out of a xtx which is 21/41, mines 24-50 stock. Crazy low!

Yes 24-50 is low, 21/41 is an all around great gear ratio for any of these sleds with the 9 tooth drivers. The taller gearing really pulls a lot of clutch theory all together in more ways than just top speed..for 1, lower gearing is just revving the engine and wasting time, these engines need a load on them to perform. Probably a good reason why you and cannondale are having good luck with your magnaforce weights and steeper helix's, they shift hard and load the engine the whole way. The taller gearing is gonna keep u more efficient on the clutches which means many things: better top speed, more consistent top speed, better fuel mileage and longer belt life. Kinda a shame they still aren't putting taller gearing in these things, there really is no downfall to it. For another comparison, my cat 800 has 21/38 gearing, my cousins has 21/41..both almost identical in power, same clutching..only difference is I weigh 75 pounds more than him. From 0-40ish ours are dead even, after that mine slowly pulls away..1-2 sled lengths at 100 mph even with a big weight disadvantage. So it's not just a 4 stroke thing, different engines, same outcome. 21/41 gears and 86 pitch chain, just search xtx part numbers, it's a very reasonably priced setup.

 

[Allan]

MTX , 21-49, (2.33) 7 - Tooth driver
BTX, 21-49 ,(2.33) 8 Tooth driver
STX , LTD, RTX. 24-50 , (2.08) 9 -Tooth Driver/
XTX 21-41 ,(1.95) 8 - Tooth Driver.

How do the driver change the gearing of a machine?

 

[cannondale27]

Smaller driver lowers overall larger is higher. Think of driver like a tire on truck or car.

 

[Allan]

Smaller driver lowers overall larger is higher. Think of driver like a tire on truck or car.

So the MTX AND BTX has same gears but BTX has 8 tooth driver and MTX has 7 tooth driver. The 8 tooth would be faster than the 7 tooth?

 

[blueironranger]

All 1:1 clutch ratio speeds
MTX = 77mph
BTX = 88mph (XTX LE also)
XTX se = 105mph
RTX/LTX = 105mph

RTX/LTX have a lower ratio to make up for 9/2.86 drivers vs XTX to arrive at the same speed. I think they should have just used the same 24/50 on the XTX which would have given 98mph 1:1.

As you can also see, 7 tooth to 8 tooth “allows” an extra 11mph

 

[Mark Seavey]

All stock Vipers are 24/50 gearing. They lowered the Cat gearing because the Cat clutch pulls overdrive easier than Yamaha so I heard. But looks like you have proved that wrong since gearing up helped you.

At the end of the day its a gear box. So when turning the out put with the 21/49 sprockets it takes 2.333 turns on the in to make the out turn one time. With the 24/49 it takes 2.04 turns on the in to make the out turn one time. So with rpms the same it gives me the extra track revolutions to gain the 8 mph.

 

[cannondale27]

At the end of the day its a gear box. So when turning the out put with the 21/49 sprockets it takes 2.333 turns on the in to make the out turn one time. With the 24/49 it takes 2.04 turns on the in to make the out turn one time. So with rpms the same it gives me the extra track revolutions to gain the 8 mph.

Dont forget about the clutch though.

 

[Studroes144]

Dont forget about the clutch though.

Exactly, theoretical speeds only look good in writing. Even though the gearing is low and these trail sleds are only geared for 105 mph..doesn't mean they're gonna always do it. Efficiency and consistency is what it gonna do it.

 

[srvfan]

anybody know the stock gearing on an 05 Vector ? just curious because my vector carries close to 1000 rpm less to cruise at 30-35 mph tight trail speeds yet it is faster on top than my 16 Viper , not too mention the vector is good for 3-5 more MPG ? Doesn't make any sense since the Vector is down at least 15 HP to the Viper, at least at the crank. At the rack might be different story. Just added BOP soft spring so that may help drop Viper RPM and MPG when just cruising slow.

 

[blueironranger]

Exactly, theoretical speeds only look good in writing. Even though the gearing is low and these trail sleds are only geared for 105 mph..doesn't mean they're gonna always do it. Efficiency and consistency is what it gonna do it.

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.

 

[rx1 fern]

Wonder if a gear change on my ltx would help .Just installed a backcountry 1.75 . Way better track . I’m stock gearing still. Thanks

 

[srvfan]

help me out with some theory . I understand the basics of clutch tuning pretty well. So lets say I have my clutch set up to turn 9k RPM are you guys saying that the gearing is also inefficent and that by gearin up I can increase top speed and MPG but my total RPM would be bout the same at 9k? or that it would drop RPM to say 8600 while gaining top speed? In which case I would then want to reclutch the new gear setup to get back up to 9k and gain even more ?

 

[cannondale27]

help me out with some theory . I understand the basics of clutch tuning pretty well. So lets say I have my clutch set up to turn 9k RPM are you guys saying that the gearing is also inefficent and that by gearin up I can increase top speed and MPG but my total RPM would be bout the same at 9k? or that it would drop RPM to say 8600 while gaining top speed? In which case I would then want to reclutch the new gear setup to get back up to 9k and gain even more ?

Nobody said that except Studroes who added turbo and has the power available to "gear out" with stock gearing. I do not have enough hp to gear out with stock gearing or taller. But with stock gearing top speed is reached using overdrive available in clutch. Overdrive is very inefficient on a CVT clutch. Therefore it is less reliable due to other factors such as snow conditions. Using taller gearing is more efficient for the clutch so you will see the same top speeds more often than with stock gearing. The gearing does not change rpm much if at all since the clutch is tuned for peak power and that doesn't change with gearing.

 

[blueironranger]

help me out with some theory . I understand the basics of clutch tuning pretty well. So lets say I have my clutch set up to turn 9k RPM are you guys saying that the gearing is also inefficent and that by gearin up I can increase top speed and MPG but my total RPM would be bout the same at 9k? or that it would drop RPM to say 8600 while gaining top speed? In which case I would then want to reclutch the new gear setup to get back up to 9k and gain even more ?

If it’s isn’t a drastic change in gearing you won’t notice a change in RPM. I’ve gone a tooth or two on the upper gear of previous sleds and never had to tinker with the weights.