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went from a 3/4" 121 with 192 studs and was clutched perfect . I had no problem putting the speedo needle straight down at the equivelent of 120 mph ( I know thats not the real speed but thats a different story lol ) to my 1 1/4" X 136 ripsaw track ( I did expect to give up some top end but not an indicated 35-40 mph ) just feels like it isnt shifting all the way out so any advise you guy`s can give would be appreciated . tia Mark
 

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Well you're not just pushing more total weight but the mass of your track has been greatly increased. In my experience tuning the Vmax, increasing the ratio from 19/39 to 17/39 let me keep the clutching stock but gave me a ton more performance, especially low end and mid range. I got the sled with 19/39 but 21/39 was stock, so I'm a long way from stock. If you delve into clutching you're kinda guessing (I assume or you wouldn't have made this post) but gearing is more straightforward and you can look at it as you're just returning the balance to the clutch as it was. If you regear, the clutch will "feel" less track mass, as it did before your upgrade. You are never going to get that same top speed back because of all the added mass, so it makes sense to gear down. Since your clutch was already perfectly tuned to your engine (if you believe that is the case) then it makes even more sense to just regear in my opinion. I would at least drop two teeth from the top gear or add 2 to the bottom and see what you get. You might need even more than that but maybe start with dropping 2 from the top then if you need more torque add 2 to the bottom. Use the SW gearing calculator to help you decide. You might not want to lose too much top speed, my wife on the indy 500 beat me in a drag race last week due to the higher top speed (gearing) than the Vmax, but then we raced uphill and the Vmax blew her away, so it's always a question of what type of performance you want. Maybe somebody more experienced can give more specific advice but that's my $.02
 

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A easy thing to try would be to start pulling some helix out of it. Try a flatter finish angle.

When I long tracked the RX-1, I went from a 121 Ripsaw out to a 136 x1.375 Cat Sno Pro track and picked up MPH after clutching it.

The track is more load, thus the need to decrease the load seen by the engine by either (1) lower the gearing and/ or (2) decreasing the torque sent by the secondary clutch.

Another good place to start is to compare gearing/ clutching from a 121 to a 136 ZRT 600.
 
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