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850 khaos primary engagement spring rpm

C
Jan 14, 2020
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Whats everyones sled engaging at? I have 68 and 66 gram epi weights (came with 68, have 68 for 10000 elevation) with stock high altitude spring (120/320lbs) and sled doesnt start to move until 4100 rpm, on slomo video. And it is pretty jerky feeling. What spring can I get to get a 3400-3600 rpm engagement, i feel like this will cause bad trenching in my dry sugar snow.
 

damx

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My sled moves around 4000 rpm, nice and smooth, but I'm running trs weights stock spring. I also have my weight to shive clearance set proper, that helps alot with the smooth engagement.
 

Wheel House Motorsports

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worn belt, Loose deflection and belt to sheave will make for some pretty rough engagements. just a fresh belt with tight deflection should get most guys into a very nice engagement. When everything is setup right the takeoff is borderline electric feeling, no sudden lurch.

Not many spring options to drop engagement much lower for these clutches honestly. 120 is a fairly low start rate.
 

carbontj

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tighten up your belt deflection..that will lower it some and make it smooth..if still high you could check you belt clearance on the primary..should be .020-.025. if higher it will make it engage harder and higher...I know most stock clutches are around .030...I change many for customers, before balancing...As WHM said 120 start rate is real low...
 
C
Jan 14, 2020
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tighten up your belt deflection..that will lower it some and make it smooth..if still high you could check you belt clearance on the primary..should be .020-.025. if higher it will make it engage harder and higher...I know most stock clutches are around .030...I change many for customers, before balancing...As WHM said 120 start rate is real low...
WELP, i installed the dalton 100/305 lb primary spring with new 66.5 gram EPI weights, and my engagement is now 4000 rpm lol. softer feeling with the new belt, but still high RPM.

And i havent checked belt clearance, but i imagine if i can slap the belt back and forth with noticeable play on a brand new OEM belt, my sheave to belt clearance is very large.

oh well, i thought i had'er fixed for 4 months in the future lol. thanks guys you all are awesome.
 
C
Jan 14, 2020
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My belt to sheave clearance is between 42 and 46 thousandths, checking with belt ON the sled.

Going to be taking it all apart again to check it properly and get shims, YAY.

If you have a new polaris definitely check out the clearance as above posts have said they regularly see clutches way too loose.
 

Teth-Air

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WELP, i installed the dalton 100/305 lb primary spring with new 66.5 gram EPI weights, and my engagement is now 4000 rpm lol. softer feeling with the new belt, but still high RPM.

And i havent checked belt clearance, but i imagine if i can slap the belt back and forth with noticeable play on a brand new OEM belt, my sheave to belt clearance is very large.

oh well, i thought i had'er fixed for 4 months in the future lol. thanks guys you all are awesome.
Are those the EPI adjustable weights?? You can load the heel in those and have lower engagement without hurting the upper rpm's.
 

ewanaburner

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your belt to sheave clearance can and will change with different brands of weights so it is good practice to check whenever you change styles o weights
ie. TRS ,EPI ,Indy Speciaties all require different shimming to work properly
 

carbontj

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most stock clutches have around like you say .040 belt clearance...I suggest .020-.025 to make a softer/smoother engagement..If someone wants us to adjust there clearance we ask for the belt they use and shim from there...Then we balance the clutch as it changes the sheave locations..Most aftermarket weights are real close to stock Polaris weight but we also suggest sending us your weights...there are a few brands the will change clearance for sure..If your clutch is slamming from big clearance your losing some bottom end...
 

Teth-Air

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most stock clutches have around like you say .040 belt clearance...I suggest .020-.025 to make a softer/smoother engagement..If someone wants us to adjust there clearance we ask for the belt they use and shim from there...Then we balance the clutch as it changes the sheave locations..Most aftermarket weights are real close to stock Polaris weight but we also suggest sending us your weights...there are a few brands the will change clearance for sure..If your clutch is slamming from big clearance your losing some bottom end...
This advice is only as good as the condition of your belt. Too many guys run their belts for far too long and they do thin out over time. I personally am looking forward to the P-22 clutch with its belt width compensation. Thanks Cat for starting this trend.
 

TRS

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This advice is only as good as the condition of your belt. Too many guys run their belts for far too long and they do thin out over time. I personally am looking forward to the P-22 clutch with its belt width compensation. Thanks Cat for starting this trend.

To be honest it only compensates for belt deflection.
I agree with your narrow belt issue most don’t recognize.
For those who wonder what I’m talking about here is a simple explanation.
A narrow belt will still open up the belt to sheave measurement. When that happens it not only raises engagement, but also changes how the flyweights work. The flyweights have to shift out(lose effectiveness)before the moveable contacts the belt. You will loose belt grip all the way through the shift.
It’s like starting out with your pickup in 3rd gear.
 

Reg2view

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Have routinely experienced the poo belt fade, after 500 miles or so, deflection perfect, sheeves clean, belt washed, belt clearance within spec along with belt width, no pulled cords, starts losing 100, then 150 rpm. New, clean, broken in belt, same length, set deflection, whamo, max RPM back. Compound breaking down, cord fatique, small width loss - don't start to chase RPM loss without a new, belt with clearance and deflection set, to start.
 

Sheetmetalfab

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……..
Have routinely experienced the poo belt fade, after 500 miles or so, deflection perfect, sheeves clean, belt washed, belt clearance within spec along with belt width, no pulled cords, starts losing 100, then 150 rpm. New, clean, broken in belt, same length, set deflection, whamo, max RPM back. Compound breaking down, cord fatique, small width loss - don't start to chase RPM loss without a new, belt with clearance and deflection set, to start.
It’s width.
That’s it.
 
C
Jan 14, 2020
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Are those the EPI adjustable weights?? You can load the heel in those and have lower engagement without hurting the upper rpm's.
no. just regular. its just whatever EPI carls cycle sold me.
your belt to sheave clearance can and will change with different brands of weights so it is good practice to check whenever you change styles o weights
ie. TRS ,EPI ,Indy Speciaties all require different shimming to work properly
yes, epi 68 were on before, now epi 66 gram, it was loose before with a badly worn belt.

This ~0.045" clearance is with a brand new, 0 mile belt.

Question: have any of you ran the gates redline or c12 carbon gates belts on the polaris 850 motors? They are like $100 less for carbon and $65 less than OEM belts.
 

TRS

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This ~0.045" clearance is with a brand new, 0 mile belt.

Question: have any of you ran the gates redline or c12 carbon gates belts on the polaris 850 motors? They are like $100 less for carbon and $65 less than OEM belts.

You definitely need to tighten that up.
We have been running the C belt for a long time. Last year we ran and offered the R belt. Alignment is paramount when running any carbon cord type belts.
I had Gates build a custom R belt that I offer for sale. It’s a bit wider and longer than the stock belt and retains the 26* belt angle.

4E0B9622-B0FC-47C1-B603-CD176B7DB6E3.jpeg
 

ewanaburner

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I have run gates c12 and R belts since they have come out with them
I take the Polaris belt off when the sled is delivered and install a gates and put the new Polaris back on when I sell the sled
 
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