Just a little FYI on the Polaris CFI Engine and surrounding rumors

prairie-rider800

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Figured some people might like to see this....
Here is a set of Pistons out my stock 2013 Pro Rmk 800 with 1400 miles (at least half or more in mountains).
piston intake side.jpg
piston exhaust side.jpg
pistons top.jpg
 

BILTIT

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For those looking at the doo bypass t-stat i will weigh in my experience. I run the terra-alps aluminum housing bypass t-stat (very similar to the doo setup but larger t-stat) and it definately runs much cooler.

In anything over 2" of powder it will run 115F all day long, helps run cooler longer when i am on the trails/hard snow here at home too. I think it is a very good upgrade for these machines.

It warms up faster and will not get hot just sitting and idling, the cold shot is reduced when stuck or sitting for periods of time too.
 

ditch1000

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For those looking at the doo bypass t-stat i will weigh in my experience. I run the terra-alps aluminum housing bypass t-stat (very similar to the doo setup but larger t-stat) and it definately runs much cooler.

In anything over 2" of powder it will run 115F all day long, helps run cooler longer when i am on the trails/hard snow here at home too. I think it is a very good upgrade for these machines.

It warms up faster and will not get hot just sitting and idling, the cold shot is reduced when stuck or sitting for periods of time too.

X2. I 've been running this bypass thermostat for the last 2 seasons... 1st thing I would do if I was buying a new PRO!!
 

gdhillon

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prairie rider those look pretty good dont they?....im no expert on pistons

Did all the 13s have jackshaft issues?
 

prairie-rider800

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prairie rider those look pretty good dont they?....im no expert on pistons

Did all the 13s have jackshaft issues?

Im no expert either but I thought they looked great! Everybody posts when they have problems but not to often people post when things are good. So I figured I'd post some positives!.... No I don't think since the update many people have had issues. They are using the same jack shafts in the 14s and I believe the 15s too.
 

RK Tek

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Im no expert either but I thought they looked great! Everybody posts when they have problems but not to often people post when things are good. So I figured I'd post some positives!.... No I don't think since the update many people have had issues. They are using the same jack shafts in the 14s and I believe the 15s too.


Please measure the SKIRT of both pistons.. THIS SKIRT AREA is where the issues lie.. You can not "look" at a piston and tell its dimensions..

Compression checks tell you nothing about the health of the skirt.. Neither does a visual inspection..

Only a precise measurement of the skirt area will tell you the state of health of the piston..
 

rmscustom

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Nice to see ya back Kelsey.

What do you think the vertical lines on the intake side are from on them pistons?
 

prairie-rider800

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Please measure the SKIRT of both pistons.. THIS SKIRT AREA is where the issues lie.. You can not "look" at a piston and tell its dimensions..

Compression checks tell you nothing about the health of the skirt.. Neither does a visual inspection..

Only a precise measurement of the skirt area will tell you the state of health of the piston..

ok thanks for the info! That's good to know. I would measure them and post the results but I do not have a micrometer. I had to have the dealership check clearance on the new ones.
 

prairie-rider800

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Nice to see ya back Kelsey.

What do you think the vertical lines on the intake side are from on them pistons?

Thats what I was wondering aswell. They seem pretty minor though. You can't feel them to the touch... Maybe it wasn't warmed up quite enough once?
 

rmscustom

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Thats what I was wondering aswell. They seem pretty minor though. You can't feel them to the touch... Maybe it wasn't warmed up quite enough once?
I was thinking that or a poorly sealed intake... Would like to hear from the experts on that though.
 

CatRyder88

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Well those aren't the greatest pistons. Tops look ok but scuffing on the side says it may not have been warmed up enough. Im no expert but you may want to check compression. Maybe some water got into the engine.
 
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