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Discussion Starter · #1 ·
I have read numerous posts about 900's topping out at 115-120 MPH. Recenlty there have been some posts about changing helixes to get more top speed, suggesting that the clutches are not fully shifting out.

I have an 05 900 that has never blown a belt and has always run strong. In good conditions it tops out at 107 MPH measured with a GPS. It has stock clutching and gearing (25/37) and runs 7450 RPM. The gearing chart in the 05 Service Manual shows that a jackshaft RPM of 7500 RPM should result in a track speed of 109 MPH. Based on this info it looks like I am getting all there is to get with this gearing. It could be that I am not reading the gearing chart correctly.

I have seen all the pictures of the speedo showing 120 MPH and there are plenty of posts that suggest that some of these sleds are much faster than others. I am not that concerned about top speed but I would like to understand how some of these sleds run these higher speeds.

Perhaps some of you with sleds that run 115-120 could provide some info on RPM and gearing.

Thanks
 

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I have read numerous posts about 900's topping out at 115-120 MPH. Recenlty there have been some posts about changing helixes to get more top speed, suggesting that the clutches are not fully shifting out.

I have an 05 900 that has never blown a belt and has always run strong. In good conditions it tops out at 107 MPH measured with a GPS. It has stock clutching and gearing (25/37) and runs 7450 RPM. The gearing chart in the 05 Service Manual shows that a jackshaft RPM of 7500 RPM should result in a track speed of 109 MPH. Based on this info it looks like I am getting all there is to get with this gearing. It could be that I am not reading the gearing chart correctly.

I have seen all the pictures of the speedo showing 120 MPH and there are plenty of posts that suggest that some of these sleds are much faster than others. I am not that concerned about top speed but I would like to understand how some of these sleds run these higher speeds.

Perhaps some of you with sleds that run 115-120 could provide some info on RPM and gearing.

Thanks[/b]
What did your speedo say when your gps said 107 ??
 

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instead of starting a new post for this information, why don't you spend the time to read the hours worth of post's that address your concerns?

Not trying to be rude or anything. but everything you need to know is already on this forum in currently active post's.

Take a look around, take notes, and make your sled better.
 

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Discussion Starter · #4 ·
For Torquemonster... the speedo seems relatively accurate and would show anywhere from 108 to 110 on various runs. My GPS was a couple MPH less. I assume this was track slip.

For G20...no offense taken from your post. I have read all of the posts including the 3 threads on SnoWest that you recommended. I uderstand the basics of clutching and learned a lot from Indydan's and others comments. The last thread was a little tedious with the p***sing contest that errupted. I have ordered the suggested helix and will try it with the stock primary as you and others suggested.

My question is how do some of these sleds run as fast as they do? Let's ignore all of the clutching and belt issues for a moment. If the clutches are fully shifted out at full throttle, top speed is a function of engine RPM and gearing if there is adeqaute traction.

Assuming the Polaris gearing chart is accurate, to do 120 MPH you either need to spin the motor much higher than what has been recommended or run a lot more gear. If my math is right 7800 RPM and 26/36 would be close to 120 MPH. I have read several posts where people have gone to a 26 top gear with the stock 37 bottom gear.... at 7500 RPM this would be about 113 MPH not 120 MPH.

I am just trying to reconcile conflicting inputs... some of these sleds do run in the 115-120 range while the gearing chart says this takes a lot more gear and RPM than seems reasonable. Is the gearing chart wrong? Do clutches shift out beyond 1:1? Are some of these high top speeds from much taller gearing than stock?

Thanks for your input.
 

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For Torquemonster... the speedo seems relatively accurate and would show anywhere from 108 to 110 on various runs. My GPS was a couple MPH less. I assume this was track slip.

For G20...no offense taken from your post. I have read all of the posts including the 3 threads on SnoWest that you recommended. I uderstand the basics of clutching and learned a lot from Indydan's and others comments. The last thread was a little tedious with the p***sing contest that errupted. I have ordered the suggested helix and will try it with the stock primary as you and others suggested.

My question is how do some of these sleds run as fast as they do? Let's ignore all of the clutching and belt issues for a moment. If the clutches are fully shifted out at full throttle, top speed is a function of engine RPM and gearing if there is adeqaute traction.

Assuming the Polaris gearing chart is accurate, to do 120 MPH you either need to spin the motor much higher than what has been recommended or run a lot more gear. If my math is right 7800 RPM and 26/36 would be close to 120 MPH. I have read several posts where people have gone to a 26 top gear with the stock 37 bottom gear.... at 7500 RPM this would be about 113 MPH not 120 MPH.

I am just trying to reconcile conflicting inputs... some of these sleds do run in the 115-120 range while the gearing chart says this takes a lot more gear and RPM than seems reasonable. Is the gearing chart wrong? Do clutches shift out beyond 1:1? Are some of these high top speeds from much taller gearing than stock?

Thanks for your input.[/b]
You have to do your math from jackshaft rpm, polaris clutches shift out to 1:1.12 not 1:1 for example IF... you get to full shift out 7500rpm on the tach=8400 at the jackshaft.stock gearing is usually to tall to alow full shift and thats why gearing down sometimes results in higher top speed.on the same note usually gearing up will result in a slower sled because the engine will be overloaded.modded engines will pull the higher gear stock wont.
 

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Riff Raff -
I am typically right around 7600rpm (by sled's digital display) when I've gotten the 113-114mph. All stock 05' 900 w/updates + 144 studs. 210miles on sled.
Maybe important note: Same conditions best speed was approx 104 until 60 or so miles. 108 til 100 miles or so and then by somewhere in mid 100 mile range it loosened up and put down repeated 112-114mph. All updates where performed before I rode sled for 1st time - therefore all that was done was gas/oil for my 210 miles.

Snow/ice conditions where ideal for top speed throuought that mileage. I raced for most of those miles since we had no snow for the trails. There was nothing else to do, unfortunately.

I'm not near the 120 yet, but hopefully that info will help along with what others hopefully add.

I just bought the suggested Helix too, just like others waiting for snow to test + ride.
 

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I think a lot of the variations come from the motor moving all over. I installed the slp mounts and one I made and it way more consitant now. Last year it was fast at the begining of the season and then had no top end but the motor would rev. Broken motor mounts was the cause.

I highly recommend the helix (66-44). After reading about it here and from indydans post on snowest, I got one. Last night I finaaly got to try it in the feild by the house with the whole 2" of snow we got. All I can say is holy shit. My sled is geared 24/38 and with this helix it came to life!! It pulls unbelievblyhard. Not sure about top end becuase of the distance I was running in but I hit 90 no problem and it was no near done by the way it was pulling.

I would like thank G2O for the input he gave me on this set up and also IndyDan (if he is a member here) for sharing this input.
:beerchug:
 

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Discussion Starter · #11 ·
Thanks for the responses.

I had assumed the best you could get with the clutches fully shifted out was 1:1 so engine RPM would be the jackshaft RPM. If they shift out to more than 1:1 as suggested then my clutches at 107 MPH are not fully shifted out and perhaps a different helix will help.

My 05 has also had all of the updates and I dropped the top gear to a 24 mostly to improve its pull out of corners. I installed the EPI kit and did not see any significant difference. It has never blown a belt, the first 080 belt went 1400 miles and still looked good when I took it off. I added the EPI clutch kit and changed gearing at the same time and lost a couple MPH on top. This suggested that the clutches were fully shifted out with both the stock set up and the new set up. Perhaps not.

None of this matters much this year. If it doesn't get cold enough to freeze any of the lakes it will never see top end this year.

Thanks again.

PS I have one of the RPC torque stops on the bench. I plan on installing it when the helix shows up.
 

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Here is a Excell spread sheet I made from a formula for track speed.
You can change the gear numbers to show the calculated speed.
Hope the attachment works
Note the final clutch ratio is 1:1 you can change that if it is overdriving.
alsi it is set up for the 05 fusion 900 drive line
 

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One item that caught me eye in Riff-Raff's post that you guys must not have caught.

he said he used the gearing chart from Polaris!! Well look what the clutching chart did for the engineers on the stock sleds!!

I would have to agree with IndyDan on his assumptions "they must be on Crack" !!!

Also, some sleds were better set-up than others too. you really need to chack clutch alignment, steering alignment (that'll scrub alot of top-end real fast)
track tension.

Many of these sleds were way off from the factory especially the alignment and TPS values. many delaers did not properly use the "dealer prep" list and just stuck the ski's on the sled. put fuel in it and sent it out the door. SLP has a 900 Fusion tech-tip PDF file that covers the main things they found from lazy dealers and factory screw-ups. go to their site, and under the 900 twin section you'll see the link. if you cannot find it PM me an e-mail address and I'll send it out to you.

I do not think IndyDan is an HCS member. But he does have a shop in Shakopee, MN and he will do complete clutching for you guys including balancing. Just send him you clutches and he turns them around in less than a week.

Look for "Indy Specialties" on google. He also sells a Crank exchange service for the 800's on eBay.

I had to spread the information here for us HCS guys becuase we really went through alot of shit on these sleds starting in 2004. and so few had a good set-up, and if the did have a good set-up they were not going to share it with anyone.
 

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Discussion Starter · #14 ·
Thanks to ConFusion for the spreadsheet. I have not compared it to the Polaris gearing chart but to G20's comment, you have to assume that they can do the same math. I know... assume nothing. I will check it later today.

I have done all that other stuff... loosened the track, made sure tha clutches were aligned, Set the belt clearance. I put an 06 front end on it and did all the camber and toe adjustments. Like I have said, it has run really well. Doesn't vibrate any more than my XC800. It gets between 10 an 11 MPG. (I just ordered a TPS tool so I can check this for myself.) It has just not been as fast as some.

Just wondering... if it clutched right and geared right and all that other stuff... can you expect some overdrive from the clutches. Can it be as much as 12%... nowhere in the service manual does it mention this. If this is the case, this is where the missing speed is.
 

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I think a lot of the variations come from the motor moving all over. I installed the slp mounts and one I made and it way more consitant now. Last year it was fast at the begining of the season and then had no top end but the motor would rev. Broken motor mounts was the cause.

I highly recommend the helix (66-44). After reading about it here and from indydans post on snowest, I got one. Last night I finaaly got to try it in the feild by the house with the whole 2" of snow we got. All I can say is holy shit. My sled is geared 24/38 and with this helix it came to life!! It pulls unbelievblyhard. Not sure about top end becuase of the distance I was running in but I hit 90 no problem and it was no near done by the way it was pulling.

I would like thank G2O for the input he gave me on this set up and also IndyDan (if he is a member here) for sharing this input.
:beerchug:[/b]
"Holy Shit" is write. Try the 70 part of the helix. You might like it more. :div20:
 

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I think a lot of the variations come from the motor moving all over. I installed the slp mounts and one I made and it way more consitant now. Last year it was fast at the begining of the season and then had no top end but the motor would rev. Broken motor mounts was the cause.

I highly recommend the helix (66-44). After reading about it here and from indydans post on snowest, I got one. Last night I finaaly got to try it in the feild by the house with the whole 2" of snow we got. All I can say is holy shit. My sled is geared 24/38 and with this helix it came to life!! It pulls unbelievblyhard. Not sure about top end becuase of the distance I was running in but I hit 90 no problem and it was no near done by the way it was pulling.

I would like thank G2O for the input he gave me on this set up and also IndyDan (if he is a member here) for sharing this input.
:beerchug:[/b]

Rastiss,
What spring are you running in the secondary?
 

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Rastiss,
What spring are you running in the secondary?[/b]
I am currently running the black red spring with delron washers on each side. The primary is stock. I was amazed by this set up. I was actually turning 7900 before I put this in it and figured I would need to change the weights but waited to get some until I ran it to see what it would turn. To my surprise it turns 7650 consintly now. Who woulda thunk it??

For an example as to how it ran; I zipped around the feild once came back and told my dad he had to take it for a ride and tell me if he noticed any difference. He did not know anything I had done to it. When pulling back in the yard I could see him grinning inside his helmet. Before he even had his helmet off he was asking what the heck I had done.

Thanks for the tip on trying the second angle, if its better than the 66 I cant wait to try it.
 

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Ah crap - I forgot to order the delron washers with the helix - what is part # and where to get them ?
 
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