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Discussion Starter #1
I have been playing with gearing on the ZR 900 and would like to try a couple of combo's that dont work with even number chains......24/40...stock 74 link chain doesnt fit and the 76 link chain has too much curve to run efficient.....The same thing applies to 21/39 the 72 link wont fit. Can a guy make a 73 link chain or a 75 linker?? I was told that once you start messing with chains you run the risk of breaking it under load.......that would be a big mess and not a cheap repair I imagine. Does anyone have experience or info.   Thanx in advance..
 

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I have never seen an odd link chain.   Have to use em like that.   I have yet to run into the problem that you are having, if a 74 link absolutely doesn't fit, the 76 should fit good, if it was a 78 link then maybe it would be real loose.
I was calculating a few gearing ratio's and there are two more there that you didn't have in the post, try em they are close and the chain might fit a little more to your liking.
1.66 24/40
1.62 24/39
1.69 23/39

1.85 21/39
1.81 22/40
1.86 23/43
hope that helps a little
 

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Discussion Starter #4
I was trying to gear 24/40 but the stock chain is so close to fitting but just wont go....If I were to install a longer chain the next size is 2 links more and there is to much slack and the tentioner isnt long enough to take it up.   I have considered making my own tentioner bolt but if it comes to that you know there is to much chain and it has a wicked angle...almost a figure 8.  Maybe I am an idoit but I dont recall having any problems like this when I was A Bombardier guy. is this combo just not an option or what.
My concern is when you have to much angle on the chain you lose efficiency.....
 

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Well, if you want to know what pitch chain will work with a certin gear combo just use this formula:

Top gear + bottom gear div. by (2) + 40

Example: 24 + 39 = 63 div. by (2) = 31.5 + 40 = 71.5  So a 72 pitch chain will work fine.
Example: 24 + 40 = 64 div. by (2) = 32 + 40 = 72  So anytime the number comes out to equal the chain pitch it will not fit. The formulas answer must always be .5 or 1.0 differance then the chain pitch. The right numbers for a 68P chain would be 67.5 or 67. Get it !!    

           
Auggie
 

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Discussion Starter #6
Thanks Auggie
The formula will come in handy. I guess there is no possibility of running 24/40 Unless I run a 74 link. The 74 link has to much curve....  doesnt that mess with efficency?
 

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does the chain tensioner get in the way a bit when your trying to put the gears and chain on?   i have that prob and all i put do on my T-cat was to slide the rollers off of the tensioners and put the gears on, then just replaced the rollers and tightened it up. most of the time that gave me the room i needed, sometimes they just barely fit, that is still weird how 2 links bigger chain is doing that to you. How old is the chain you are trying?
does your 900 have the double roller system, or does it just have one roller on the front side of the case?
 

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Discussion Starter #8
The 900 has the two rollers and I have tried taking them off but still no go. The chain has 300 miles on it same as my sled maybe I should  run it for a while and stretch it out. Its always the thing you cant have that you want the most. I really want that gear combo
 

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Sled-head, yes it dose and also the tensioner bolt will probley be to short to take up the slack. You can use a longer bolt but it will probely bend. Anyhow I think that the chain could possibely touch in the middle.

   Auggie

PS: If that was my sled I would install 24/38 (1.58) And use the stock chain (72P) and stock top gear (24). Just my $.02
 

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Discussion Starter #10
you would gear it up?? I thought the 1.62 was to tall as it was. Dont you think it will effect the hole shot? I am sure that would be a good lake set up but we run 1000 foot stubble fields and I dont think It would work....Unless you know something I dont.
 

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Discussion Starter #12
Everyone who snowmobiles with friends lines up once in a while. I would like to have the best of bolth worlds but the area where we ride a person doesnt have the room to get top speed.....maybe once in a while when you cross a lake but for the most part the farmers fields are divided into sections and there is a road and a ditch every half mile. I would like to get the right gearing for 1000 feet and work on the clutching from there. what do you think
 

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I was told to try 23/40 in my cat but haven't yet. We all know why. With my weight, I shouldn't have probs hookin up and should have some mean acceleration! I'll have to try it next year! unless sled head, you come up with something better, let me know!
 

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Well, here's the problem. Most drag races are 660' on shaved ice with 200+ studs and great traction. This would requier one to gear down to around 22/40 (1.81/72P chain). Now if you don't have great traction (plowed field) and you run for 1000' and your geared down you will overpower (spin) the track and run out of gear on the big end. Remember when the track is spinning you are not going anywhere. There are two ways to slow down track spin, steep helix angles or gear up!! I would slip out to one of those fields with a buddy, a hand full of gears,helixes and a stop watch and have at it. Theres an old saying in racing "You gotta wanna".

   Auggie
 
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