gearing down

[dracutaco]

ok last year i tried the 25 tooth top gear in my 05 rx1er,didn't get a more speed and lost a little on takeoff,so this year i want to go down to a 23 tooth gear and am looking to find out how much this gear will affect my rpm, i am running hc primary kit and team secondary, right now my rpm is 10,200,also i am running cpr filter kit. any help or recommendations
would be appreciated. also do you think i will lose or gain speed.

 

[AaronBND]

I just went with Hartman clutching and he wants me to go from 22 to 21 teeth on the top. I am curious what this is gonna do also? Better out-of-the-whole? Will it hurt my top-end? What's the reasoning? Thanks.

Aaron

 

[Skydog]

22-21 WOW that is hole shot and you will lose some top end.

 

[dracutaco]

anyone gear down?

looking for any info on gearing down,

 

[HAMMER]

AaronBND -- I run Hartman clutching and ride in your area (Tumalo, Moon, Paulina, now in the Mt Shasta area) I don't work for him but I am his oldest son, I have been working on sleds for 25+ years, and I do help out with some of his field testing. These setups get tested and proven every single year on the snow. You can read my posts over on SnoWest and I have a few here on TY. One of the reasons I don’t post much anymore is I don’t get paid for it and it becomes very time consuming answering all the questions. I post on the forums mostly for fun. When it starts to become work it takes the fun right out of the forums. I saw your post over in the M-skid thread and before you make the final call on the clutching you should find a way to get some performance data on your stock vs changes like Track Dyno, Timing Light ETs, Radar Runs, Data-Logger Results. At a bare minimum, Elevations, Snow Consistency, Air fuel Ratios, Track Speeds, and RPMs. A seat of the pants evaluation on clutching can fool you. Almost every time you ride you'll see different environmental conditions and if you don't give Tom accurate information and performance data he can't adjust your clutching setup properly to your specific set of conditions. I’m not implying you can’t have an opinion here, everyone has right to their own opinion, but accurate data and feedback is crucial to getting the most out of your overall setup.

The gearbox is a torque multiplier.

Gearing down trades torque for speed.

1-tooth equals approximately 5-mph less on top (22 to 21)

Gear Reduction/RPM/MPH examples:

RX-1 Mountain (1:1 Clutch Ratio)

31/37 gear reduction (21/40 stock chain case)

9,800 x 83.7% = 8202 clutch rpm (82.20mph)
10,000 x 83.7% = 8370 clutch rpm (83.89mph)
10,200 x 83.7% = 8537 clutch rpm (85.56mph)

APEX Mountain (1:1 Clutch Ratio)

30/37 gear reduction (20/40 stock chain case)

10,200 x 81.1% = 8272 clutch rpm (82.25mph)
10,500 x 81.1% = 8515 clutch rpm (84.66mph)
10,800 x 81.1% = 8758 clutch rpm (87.08mph)

Driver Diameters

To get circumference multiply the amount of driver teeth by the pitch.
Then take the circumference you get from that and divide it by 3.14

7 * 3 = 21 / 3.14 = 6.68"
8 * 3 = 24 / 3.14 = 7.64"
9 * 3 = 27 / 3.14 = 8.59"

8 * 2.52 = 20.16 / 3.14 = 6.42"
9 * 2.52 = 22.68 / 3.14 = 7.22"
10 * 2.52 = 25.20 / 3.14 = 8.03"


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2005-2006 VIDEO CLIPS
http://www.putfile.com/john-doe

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Remember: These are Mountain Sleds...not...Lake Racers so the speeds are low, around 85mph tops… These clips of my Viper are evidence the Viper can be competitive in the Mountain Mod class, but it's going to cost you, its a tough class to compete in for the Yamaha faithful… Sleds in clips are 776cc Viper (me quiet SLP triples), 500lb T-Cat mod (the loud triples), SLP twin and single piped Cat 1Ms, SLP 800 RMK, 450lb 660 RMK, and a Turbo 700 RMK (didn't get the clip where he turned up the boost and smoked everyone).