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Snowmobile MPH/Gearing Calculator
-------------------------------------
2012
ROTAX E-TEC 800R
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 27
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 91.64
CALCULATED MPH --> 104.0
======================================
2012
ROTAX ACE 600
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 24
Bottom Sprocket: 51
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 71.87
CALCULATED MPH --> 81.5
======================================
2012
ROTAX E-TEC 600 H.O.
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 25
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 84.85
CALCULATED MPH --> 96.2
========================================
2012
ROTAX 600
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 25
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 84.85
CALCULATED MPH --> 96.2
=======================================
2012
ROTAX 550F
Tach RPM:6800
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 21
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 60.58
CALCULATED MPH --> 68.7
========================================
1971 ELAN with Track Pitch: 1.97 Update Not 2.52
250 ENGINE 10/25 GEAR 6500RPMS 38.8mph
-----------------------------------------
1970 OLYMOIQUE with Track pitch 2.52
12/3 ENGINE 10/25 GEAR 6500RPMS 49.6mph
335 ENGINE 11/25 GEAR 6500RPMS 54.6mph
-----------------------------------------
399 ENGINE 16/34 GEAR 7000RPMS 62.8mph
=========================================
1971 OLYMPIQUE with Track pitch 2.52
300 ENGINE 15/35 GEAR 6500RPMS 53.1mph
335 ENGINE 15/34 GEAR 6500RPMS 54.7mph
-----------------------------------------
399 ENGINE 16/34 GEAR 6500RPMS 58.3mph
399 ENGINE 16/34 GEAR 7000RPMS 62.8mph
=========================================
1970 TNT with Track pitch 2.52
292 ENGINE 10/25 GEAR 6500RPMS 49.6mph
335 ENGINE 16/34 GEAR 6500RPMS 58.3mph
-----------------------------------------
399 ENGINE 16/34 GEAR 6500RPMS 58.3mpn
399 ENGINE 16/34 GEAR 7000RPMS 62.8mpn
-----------------------------------------
640 ENGINE 20/34 GEAR 6500RPMS 72.9mph
640 ENGINE 20/34 GEAR 7000RPMS 78.6mph
=========================================
1971 TNT with Track pitch 2.52
292 ENGINE 15/34 GEAR 6500RPMS 54.7mph
340 ENGINE 16/34 GEAR 6500RPMS 58.3mph
-----------------------------------------
440 ENGINE 16/34 GEAR 7000RPMS 62.8mph
640 ENGINE 20/34 GEAR 7000RPMS 78.6mph
775 ENGINE 22/34 GEAR 7000RPMS 86.4mph
=========================================
 

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You say a 71 elan with 10/25 gearing @6500 rpm's will do 49.6 mph? I can't get the 377 elan geared at 17/34 to do that. It will probably do 40 tops. What do i need to do to get some more out of it? I would like a gain of about 10mph.
 

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I don't see allot of that list being very accurate? I have never seen an oly go 54mph. Lol
 

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Maybe right off the lot 40 + years ago. Lol. But seriously that 377 should make the elan go like a 3 legged dog. What secondary would fit the stock double roller elan chaincase? I'm going to shove a 503 in it next season.
 

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Discussion Starter · #5 ·
You say a 71 elan with 10/25 gearing @6500 rpm's will do 49.6 mph? I can't get the 377 elan geared at 17/34 to do that. It will probably do 40 tops. What do i need to do to get some more out of it? I would like a gain of about 10mph.
If your Geared 10/25 and turning 6500rpms you should be going 49.6mph. At 7000rpms 53.4mph. If I input all the numbers right, that's what you should be doing. Math doesn't lie.

#1 Are the Numbers I input all correct?

#2 Are you actually turning the motor at 6500rpms? Is your Tach correct?

#3 Many Speedometers are wrong, have you checked against a GPS, Smart Phone Speed Ap?

#4 That is under ideal conditions, are you have a lot of Track/Clutch Slip?
 

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For sure the math is right. Maybe those numbers are dynoed under no load. I cant be getting mine up to max rpm's. I don't have a tach so i don't know.I just assumed a 377 should get the job done and it didn't.
 

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From what I have found out those calculators don't put in affect any error. Such as belt, track, drive line issue of any sort. A sled that hooks up with the snow 100% is not realistic.

Sent from my iPhone using Tapatalk
 

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Discussion Starter · #8 ·
Maybe right off the lot 40 + years ago. Lol. But seriously that 377 should make the elan go like a 3 legged dog. What secondary would fit the stock double roller elan chaincase? I'm going to shove a 503 in it next season.
Age has noting to do with it, if your actually turning it 6500rpms, and have those 10/25 Gears, it's all mechanical, and Math is all.

HP/Torque, come into play on how long it takes you to get to that 6500rpms.

Problems are, faulty Tachs, faulty Speedometers, Track Slipping loosing traction, and the Clucth Slipping is probably #1!
 

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Discussion Starter · #10 ·
From what I have found out those calculators don't put in affect any error. Such as belt, track, drive line issue of any sort. A sled that hooks up with the snow 100% is not realistic.

Sent from my iPhone using Tapatalk
Ha, that's WHY some People Win Races, and others don't, it's all about getting that Power to the Track/Ground. Whether it's a Race Car or Sled, or Bike, etc., it's all about getting it all Setup right. Like I said, Math does not lie! I'm not a Sled Race Guru by far, but if your turning your motor 6500rpms, and not even coming close 2-3mph to those speed numbers, it's not setup right. If you don't have a Tach, buy one, there cheap, $30. You have to know what Rpms your making first. Most People today have Smart Phones, get a Free Speed Ap that records your Max Speed, and Avg Speed. Only you know the condition of your Track & Clutch Belt, and Clutching is an Art in any form of Racing.
 

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Discussion Starter · #11 ·
Ok, I'm a bit curious know. What is the track pitch of an Elan and what is the clutch ratio of a 377 citation?
Track Pitch should be 2.52. I don't know this Clutch Ratio, are you meaning the Gear Ratios used? I don't know what they used with a 377.
 

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Discussion Starter · #13 ·
You say a 71 elan with 10/25 gearing @6500 rpm's will do 49.6 mph? I can't get the 377 elan geared at 17/34 to do that. It will probably do 40 tops. What do i need to do to get some more out of it? I would like a gain of about 10mph.
Your 377 with 17/34 Gears turning 6500rpms should do 62.0mph.
 

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Track Pitch should be 2.52. I don't know this Clutch Ratio, are you meaning the Gear Ratios used? I don't know what they used with a 377.
Track pitch on elans were 1,97", the 2012's you listed should have 2,86" pitch.

It's true that math doesn't lie, but you won't win no races on your calculator.
 

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IDK it says clutch ratio in the bottom left in the equation. I would love to get 62 mph with my setup. So i figured by the equation i'm only getting my sled to max out at 3800rpm @40mph
 

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Discussion Starter · #17 ·
IDK it says clutch ratio in the bottom left in the equation. I would love to get 62 mph with my setup. So i figured by the equation i'm only getting my sled to max out at 3800rpm @40mph
Ok, I see what your talking about. The Web page Calc, and this Spreadsheet show's the same Final Numbers, I just find the spreadsheet easier to make a Screen Print Photo of the Data to show you.

On the Spreadsheet, you only have to input info into the Blue Boxes, basically just Rpms used, and Both Gears used, and hit enter. Since you said you don't have a Tach, your just guessing at your Rpms. Most Sled Speedometers aren't correct, and you probably have a Clutching problem, Belt Slip.
 

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Discussion Starter · #18 ·
IDK it says clutch ratio in the bottom left in the equation. I would love to get 62 mph with my setup. So i figured by the equation i'm only getting my sled to max out at 3800rpm @40mph
You can download a Free Speed Ap for Smart Phones, or use a GPS to verify your Speed. don't Guess!
 

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I'm not guessing at the speed. I have been using a gps app. I even tried it in the car to see if it was accurate, Sled will not go any faster than 40. I could be getting belt slip. Idk how to verify that. It seems pretty tight on the clutches. I was going to try dual 34mm carbs.
 

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Discussion Starter · #20 ·
Track pitch on elans were 1,97", the 2012's you listed should have 2,86" pitch.

It's true that math doesn't lie, but you won't win no races on your calculator.
True, but the Math will tell you what you should be making if ideal conditions. Gives you a basis to go from. The web page Calc said most all Sleds used a Track Pitch 2.52, so that's what I used. Is there other old Sleds that used the 1.97 then?

Update

Snowmobile MPH/Gearing Calculator
-------------------------------------
2012
ROTAX E-TEC 800R
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 27
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 91.64
CALCULATED MPH --> 104.0
======================================
2012
ROTAX ACE 600
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 24
Bottom Sprocket: 51
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 71.87
CALCULATED MPH --> 81.5
======================================
2012
ROTAX E-TEC 600 H.O.
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 25
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 84.85
CALCULATED MPH --> 96.2
========================================
2012
ROTAX 600
Tach RPM:8000
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 25
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 84.85
CALCULATED MPH --> 96.2
=======================================
2012
ROTAX 550F
Tach RPM:6800
Clutch Gear Reduction: 1.00
Clutch Ratio: 1.00
Top Sprocket: 21
Bottom Sprocket: 45
Track Pitch: 2.52
Track Pitch: 2.86
Number Of Driver Teeth: 8
CALCULATED MPH --> 60.58
CALCULATED MPH --> 68.7
========================================
1971 ELAN with Track Pitch: 1.97 Update not 2.52
250 ENGINE 10/25 GEAR 6500RPMS 38.8mph
---------------------------------------------------------------
1970 OLYMOIQUE with Track pitch 2.52
12/3 ENGINE 10/25 GEAR 6500RPMS 49.6mph
335 ENGINE 11/25 GEAR 6500RPMS 54.6mph
-----------------------------------------------------------
399 ENGINE 16/34 GEAR 7000RPMS 62.8mph
=========================================
1971 OLYMPIQUE all with Track pitch 2.52
300 ENGINE 15/35 GEAR 6500RPMS 53.1mph
335 ENGINE 15/34 GEAR 6500RPMS 54.7mph
----------------------------------------------------------------
399 ENGINE 16/34 GEAR 6500RPMS 58.3mph
399 ENGINE 16/34 GEAR 7000RPMS 62.8mph
=========================================
1970 TNT with Track pitch 2.52
292 ENGINE 10/25 GEAR 6500RPMS 49.6mph
335 ENGINE 16/34 GEAR 6500RPMS 58.3mph
-----------------------------------------
399 ENGINE 16/34 GEAR 6500RPMS 58.3mpn
399 ENGINE 16/34 GEAR 7000RPMS 62.8mpn
-----------------------------------------
640 ENGINE 20/34 GEAR 6500RPMS 72.9mph
640 ENGINE 20/34 GEAR 7000RPMS 78.6mph
=========================================
1971 TNT all with Track pitch 2.52
292 ENGINE 15/34 GEAR 6500RPMS 54.7mph
340 ENGINE 16/34 GEAR 6500RPMS 58.3mph
----------------------------------------------------------------
440 ENGINE 16/34 GEAR 7000RPMS 62.8mph
640 ENGINE 20/34 GEAR 7000RPMS 78.6mph
775 ENGINE 22/34 GEAR 7000RPMS 86.4mph
=========================================
 
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