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Discussion Starter #1
Hi there. I'm new to this forum and hope maybe someone out there maybe able to point me in the right direction. I just purchased a 1999 ZRT 800. It's had the recall parts installed and works excellent (stock). I've been to the lake three times with good success. But there is one SRX 700 (clutch work done) thats giving me a roasting in the 1000 footer. My first concern is my studing, 144 carbides. I plan on 192 ice picks this week. I've also picked up a yellow and green drive spring and ordered a 22 tooth gear to replace my 24/39 combo. I think this should be enough but I'd like to be sure. Anybody out there have any hot setups they would like to share i.e. helix, weight and spring combos. I've talked to several people but every combo is different ,real different. Thanks in advance
 

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Is your gear combo 24 on the top, and 39 on the bottom? Cause if you put a smaller top sprocket on, i think that will make you slower, either add a tooth to the top, or go 2 smaller on the bottom from your origanal 24/39 combo!!
 

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Welcome Mr. Plow,,  have the same sled your inquiring about, allthough i am still non-traction
4000 miles, that 22 tooth gear will definetly make you VERY quick!!  but slow on the top end, so hopefully you will be done in a 1000'  An easy way to think of gearing is like on a peddle bike, On the front cassette the smaller gears will make you accelerate quickly then ya just shift into the next biggesst gear for more speed, to bad it ain't that easy for the sleds!!  Good luck, truely one of the most handsome sleds cat ever made
 

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Well, a 22T gear on the top is not the way to go. 39 div. by 22 = 1.77 to 1. Thats about the stock gearing on a ZRT600. This gear ratio will allow your eng. to overpower the track even worse then it is with the 24/39 (1.625). You can't go to a 25T gear on the top because your chain will be to short. Try a 38T gear on the bottom. That will give you a gear ratio of 1.58 and you can use your stock chain. This gear ratio will kill some of the bottom end and help keep the track from spining. I am not sure but I think that the stock drive cl. spring is a Red sp. If that is so and you install a Yellow/green sp. that will increase cl. engaugement RPM and slow down your shifting. If cl. engaugement is increased that means that you will have more HP at engaugement which will premote track spin. The whole idea is to leave the line with no track spin. If you are going to use your sled just for ice racing (no trailriding) then use Woodys steel 30 deg. ice pics. You will have to determin the proper length. 144 is all you will need. Softin the rear sup. so the rear will squat and plant the pics when you leave the line. Good Luck!

   -Auggie-
 

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Discussion Starter #5
I'm not to concerned with my total top end speed. It's not very often I get the chance to use it. I figure when the needle is to the "C" in Cat it's must be around 115 MPH or so, but when I cross the 1000 foot mark it's at 105. So gearing down a little should get me there quicker at the same speed or maybe a little faster. I was going to go with a Heart Throb kit but I need stuff gathered up by Friday, put together Saturday, kick ### on Sunday. Thats the plan anyway. I'm still open to helix and spring recomendations. Great site isn't it?
 

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Mr.Plow, here are a few things to consider. You said that you were going 105mph at the end of a 1000' track with the stock gear ratio (24/39 = 1.63). That means your eng. was at around 8000 rpm. If you gear down (22/39 = 1.77) and your eng. is running at 8000 rpm your top speed at the end of the 1000' track will be around 97 mph??? You better hope that your clutches go into overdrive. Oh and by the way if you try to install the 22T top gear you will not find a chain that will fit that gear combo. Lets do the math.

22 + 39 = 61
61 div. by 2 = 30.5
30.5 +40 = 70.5

Arctic only sells (3) different chains: 68,70 and 72 pitch.
I would recomend that you do a little more homework.
 



   -Auggie-
 

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Discussion Starter #7
Thanks for the heads up Auggie. My way of thinking was to stud it up with 192 to hold the track better. If this works I could raise up engagement RPM to leave harder and with a lower ratio leave even harder. Stuff always works better in my head then reality. As far as homework goes I thought the guys at CPC Racing knew what they were talking about. They list a 22/39 combo with a 72 pitch chain on their web site. I'm a little confused with the gear ratio calculations as yours and theirs seem to clash. I talked to a local Cat racer tonight who seemed to think a 20/39 (high altitude) combo would be better. He also mentioned a yellow/white spring for the primary but then got tight liped. I'm begining to find out snowmobile racing is a little harder to get info for than drag racing. Thanks for the replies, any help is appreciated.
 

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Here is a cheep easy set up.  Leave the gears stock.  You will need the taller gear in 1000 feet with this set up and remember every time you change gearing it effects your clutch set up.   Run the cat yellow/green spring with comet AC (58.3) gram weights and a sraight 53 degree helix with a green sno-pro secondary spring.  This will cost you less than $85 and you may already have the right helix in your sled stock.  It will engage at about 4500 RPM and adjust secondary tension to shift at 8200-8300 ( start in the middle hole) and by by SRX.  If it builds to 8500-8600 RPM at over 80 MPH thats even better, but it has to pull at lower speeds at 8200 where the torque is.  GO get um!!!!!!!!!!!!!!  Dave
 

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Thanks for the schooling  in gearing auggie
 Its quite easy to figure ratio's in cars and trucks but heck
 i have never really understood ratio's in sleds,  i printed out your post  
 I usually run big sleds and don't worry about mods,,  Greg,,,
 

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Discussion Starter #10
Thanks for the advice Fastcat800. Hope I can try this stuff out soon. We've recieved around 20 inches of snow this week and I hope the plows been keeping the lake cleared off. My buddy mentioned yesterday he had a straight 53 helix I could try. Also the girlfriend dropped in last night with a yellow/green spring and clutch puller, said it was a treat. Lucky me, she also happens to work at the Cat dealer aswell. Another friend also dropped in to tell me his 95' 800 was at the race shop for a hot setup. I be thinking I'll be checking this out. Hopefully the springs aren't painted and the numbers ground off the helix. Man these guys can be sneaky. Thanks again for the info.
 
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