Geared up...got slower

[parkindale]

22/38 is higher gearing yet. It will get worse. I lost some mid-range too. if 22/39 is slower then 21/39 then for me 22/38 will be worse yet.

I dunno what to tell ya? it works well on mine ? mine dynoed at 142 stock maybe that has something to do with it??Oh ya i did a track swap & installed 1" hacksaw with 144 studs too. Also maybe rider weight has something to do with it aswell?

can you post you dyno sheet

I will soon as I get it back, I'm not sure if he kept a copy from the initial pull but if he did I will post before and after results.

 

[NOS-PRO]

Here’s a thought on the gearing changes…

At 21/39 your ratio is 0.538, 22/39 gives 0.564, and 22/38 goes to 0.574. These last two ratios represent 4.8% and 7.4% increases in torque load (all other factors equal) on the motor at any given engine speed. In order to see increases in top-end speed, which you would expect to be of the same magnitude, the motor must be capable of delivering these higher torque demands – seeing lower maximum RPM with this gear change is a sign that it’s not.

But this is where the clutches come into play. As a CVT system the clutches function to amplify torque (which is what actually makes your sled move, horsepower is only a measure of the rate that torque can be delivered). If the primary clutch is set to engage at higher RPM, and thus greater torque – to a point – you can compensate for the increased load from the higher gearing an bring back the bottom end grunt. To see the increase in top-end speed the clutches still need to move to their maximal output ratio with the RPM your engine can provide.

So, the point is; to see the speed increase you expect, changing the chain case ratio is only part of the solution. You, or someone skilled in the art, will need to reset the clutching around these new ratios in order to get all the juice out. Or, you can put more torque in your motor by pushing harder on the pistons, think turbo boost. Generally speaking, you get more horsepower when you can spin the motor up faster, which increases the acceleration you feel but not necessarily top end speed. Generally you see only small increases in torque with mods aimed at horsepower gains.

But all of this makes be wonder if anyone that has hit a tree on a mod sled thought they were going too slow on impact.

arteez - I believe you are calculating the wrong way, as 21/39 should be a ratio of 1.857, and 22/39 will give you a ratio of 1.772

That is how many times the secondary axle has to turn the drive axle.

 

[Turk]

The clutching was matched perfectly to the rpm,s. I do know my way around the yamaha cvt snowmobile drive system.

 

[pro116]

The track and studs can affect how the sled pulls the gearing especially the driver weight.Not the nytro but I have had two identical sleds testing same day one was faster with the gearing and one was slower.They both had different tracks on.

 

[700Canuk]

I like the sharing of information... so for reference... I am 178 lbs before gear.

As Ryan mentioned... I am paying a penalty for those additional track clips and studs. I did have the track on for a couple of early season rides, and there was no mph difference before and after, so I was hopeful for the taller gearing... especially after seeing those beautiful torque numbers from Aarons' stock sled (Excell Exhaust).

With the taller gears, sled was pulling 8700 initially, then 8,900 by the end of the run.

By no means am I saying this set-up will not work, as I have data from someone else to suggest otherwise (hey... that's why I invested my own $$$ to try this out). But when the sled is pulling very close to the target RPM... and it is now almost boring to ride... the tall gearing comes out.

PS
I have not given up. I love clutching/gearing... that's why I race all year round... but for me anyway, the trade off for that last few mph will probably end up being too great.

 

[parkindale]

I like the sharing of information... so for reference... I am 178 lbs before gear.

As Ryan mentioned... I am paying a penalty for those additional track clips and studs. I did have the track on for a couple of early season rides, and there was no mph difference before and after, so I was hopeful for the taller gearing... especially after seeing those beautiful torque numbers from Aarons' stock sled (Excell Exhaust).

With the taller gears, sled was pulling 8700 initially, then 8,900 by the end of the run.

By no means am I saying this set-up will not work, as I have data from someone else to suggest otherwise (hey... that's why I invested my own $$$ to try this out). But when the sled is pulling very close to the target RPM... and it is now almost boring to ride... the tall gearing comes out.

PS
I have not given up. I love clutching/gearing... that's why I race all year round... but for me anyway, the trade off for that last few mph will probably end up being too great.

Well that through's the weight theory out the window, i weigh about the same

 

[orange]

up around hayward say 102 on a hard pack lake with a 136x1.5 ripsaw, stock clutching, my buddys has the same set up and same result. My one friend weighs rite at 400lbs and he can still get 97 on the speedo.

 

[Srxspec]

The reasons not to gear up would be: 1-using a taller than stock lug height & 2-being anything over 240 lbs from what I've seen in testing. Now I have not tried gearing up using stock clutch components, but I do know it works with the proper clutching (as long as you don't fall into #1 or #2 reasons above). I have seen several sleds with 23/39 gearing that gave up nothing to a stock sled in the low end and at 85 mph could drive away effortlessly. Gearing up may not be for everyone, pick & choose by your rider weight & riding style.

 

[gormleyflyer2002]

I'm 240 and went to 22......its been all good.

not a lot of WFO testing or lake running, but corner to corner less buzzy.....but strong.

 

[unchained]

The reasons not to gear up would be: 1-using a taller than stock lug height & 2-being anything over 240 lbs from what I've seen in testing. Now I have not tried gearing up using stock clutch components, but I do know it works with the proper clutching (as long as you don't fall into #1 or #2 reasons above). I have seen several sleds with 23/39 gearing that gave up nothing to a stock sled in the low end and at 85 mph could drive away effortlessly. Gearing up may not be for everyone, pick & choose by your rider weight & riding style.

Yeah Im 185 and put a 1" hacksaw on and get 100 GPS with 10 tooths and like Ulmer said, I didnt give up anything before 85 except now its rideable from corner to corner and less wild---overall speed from 0-85 is still right there though....

 

[4bangpower]

I weigh 165 w/o gear on and my 40th RTX w/ 22/38 gearing pulls harder and has managed to pick up atleast 7-9 mph on top end vs. stock gearing.

Two weeks ago in the U.P. I was balls to the wall on a plowed near perfect road and saw 111 on dream-o-meter w/ aftermarket clutching installed.

Identical road and weather conditions, I was only able to pull 103 with stock gearing w/ same clutch kit.

Never tested gear change w/ stock clutch set up.

As Ulmer stated "It does work," but gearing may not be everyone.

 

[nytro boy]

I have the Ulmer stage 2 clutch kit with excell exhaust with 22 top gear and after a ton of testing last weekend I find the bottom end to be ever so slightly slower which helps with traction and the mid and top end the same> I cannot get it over 100mph in any condition. The dealer and I are going to test the stock clutching and aftermarket and gearing on the lake Saturday to see the difference................can you use a 38 lower gear with reverse? and will it help any for top end? Thx

 

[Srxspec]

Nytro Boy are you running 8,800-9,000 rpm? Send an email or PM (PM may be better as I have had emails going in my bulk folder lately and sometimes I do not catch them).

 

[nytro boy]

Nytro Boy are you running 8,800-9,000 rpm? Send an email or PM (PM may be better as I have had emails going in my bulk folder lately and sometimes I do not catch them).

Hey Allen,

Depending on snow conditions I run 8700 when hooked to 9100 plus when slipping and run right around the 8800 top end......... I will PM you shortly, I know with your kit and help I will be able to better this........

Thx

 

[NB-NYTRO]

I geared mine up with a 22tooth top gear and as of last weekend I saw 108mph on the speedo. The best I seen before was 96mph with stock gearing. I'm also running a Proline clutch kit and CR10EK plugs. Its working real well now. It pulls as hard as stock out of the hole if not harder and the top end is much improved. I initially had a bad belt problem. I installed a new belt and it seems to working well with the exception of cement hard trails with no cooling.