i want to freshin up the top end in my 2011 polaris pro 800 163. so far from the research i've done rtk pistons seem to be the best bang for the buck, ($400) to my door in canada. anyone have any other suggestions? cheers. 
has any one put different pistons in there pro???
- Thread starter tylbz
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edavis0202
Well-known member
i want to freshin up the top end in my 2011 polaris pro 800 163. so far from the research i've done rtk pistons seem to be the best bang for the buck, ($400) to my door in canada. anyone have any other suggestions? cheers.
Just another option...Mountain Tek "The Fix" kit...has been on proven for many years to work in the dragon and now on the PRO. The piston is taller and requires a shim on the bottom of the cylinder (included in kit). This help with side loads.
I think I paid around $550 for it for my 2012.
My $0.02
i put a mtn tech kit in my friends sons dragon.cured his rpm issues and ran great.just put a rkt drop in kit in my 11 pro have been able to run it but it looks good fit on piston alot tighter,foud rings flaking at 1000 miles on stock pistons on itake side,hoping to cure my low rpm issues,both kits looked good i don,t think you could go wrong with either one.
ps treedocker has kits for 700.00 with billet head great guy to buy from.
ps treedocker has kits for 700.00 with billet head great guy to buy from.
I know someone who is talking about having some custom ones made..no idea when/if they will be available..if he does go thru with building them..they will be the only ones I would consider running(they will be built by the best piston manufacturer out there, using totally different materials then anyone else uses in the sled industry)hopefully he will make these available to the general public........
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RKT
Well-known member
We also have direct replacement pistons for the Pro.. No head required.. These will address the OEM piston issues we have found.. They are priced very nice, and in stock..
They are a very custom piston made to our spec.
Call if you have any questions
Kelsey
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edavis0202
Well-known member
I'm running the 858 so didn't need to look into drop in pistons... but had I kept my 11 and not done a BB on it I would have done it. I've chatted with Kelsey at length about these and have recommended them to a bunch of my buddies in Spokane area... It really seems like the way to go if you're doing a top end!!
Wiseco ??
Can anyone comment on the forged Weisco pistons.
Can anyone comment on the forged Weisco pistons.
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R44guy
Well-known member
John, the wiseco piston is a great choice with several options and has been proven real well in the Mtntk fix it kit. I have had great luck with the kit in my D8 but I am still under the factory engine warranty in my pro assault right now with pretty low miles after the limited riding season last year.
I am in the same boat as you. 2011 Pro 800 163" 800+ miles.i want to freshin up the top end in my 2011 polaris pro 800 163. so far from the research i've done rtk pistons seem to be the best bang for the buck, ($400) to my door in canada. anyone have any other suggestions? cheers.
But I have two years left on the warranty so I am at odds as what to do.
I have three options as I see it.
#1 Turn up the oil pump and let it be.
#2 Have my dealer replace the pistons. That should keep the warranty valid. Then turn up the oil pump
#3 Go with the after market, and invalidate the warranty.
I don't want to drive 1000+ miles to my favorite destination and have a motor blow on me.
Suggestions please!!!!!
400$ tip,turn up your oiler when you install your brand new RKT direct replacement pistons.they are scary lean on oil ratio,so your rod bearings will thank you in the long run.
With regard to our experience with Wiseco pistons in a Carl's Cycle 910, piston to cylinder wall clearance blue-printed at the time of engine assembly was .0045" - .0055"...............After several rides the engine was diassembled for other reasons(burning coolant), piston to cylinder wall clearance was measured again out of curiosity and the clearance had risen to .0095 - .010"!!! The skirts had collapsed damn near .005" after less than 100 miles!!!
New pistons were installed(clearance back to .0045" - .0055")when the engine was re-assembled and sled was ridden for a hand full of rides but the "coolant burning" issue remained so the engine had to be diassembled again to find out what the problem was.............While the engine was apart to investigate, we checked the second set of pistons - They had collpased as well in less than 300 - 400 miles!!! Ironically, if it wasn't for the coolant burning issue, which turned out to be a crack in the exhaust port, we never would've known the pistons were collapsing as the engine ran fairly strong..............
After speaking with several people who make their living building 2 stroke engines, the consensus was the same - Wiseco pistons start collapsing the minute that you drive out of the parking lot & probably are totally collapsed in 100 miles...............
With many engines, the fact that the piston collapses doesn`t seem to matter as the engine is built rugged enough to tollerate the excessive clearance however given the vulnerability of the Polaris 800 cylinder skirts, a Wiseco piston would be my absolute last choice!!! IMHO..................
pretty simple..a forged piston needs more expansion space but it is a stronger piston, a cast piston expands less, isnt as strong(especially to deto)and a hyperetectic is about in the middle ..better then cast for toughness but expands less like a cast..all sled pistons are made out of a silicon based aluminum...they work..but there is non silicon pistons made(1 company builds them..they are spendy..but they put any silicon piston to shame), problem is no one so far as stepped up and built them for a sled(I know someone who is thinking of doing this for the pro)..with the issues the pro has with cylinder/piston I dont know that a forged piston will survive.wall clearence becomes critical and if it is tight enough to take the load off the skirts it will most likely scuff when the piston gets hot on a long full load climb..loosen it up enough to live under those conditions and it beats the skirts off it when its cool...cast pistons are under the same issue but because they expand less they are living for a while..if you can hand size the cylinder for each piston, they live better and longer....thats the basics of it...
This is totally correct. The Fix Kit from MTKTK has been around much longer than anybody elses aftermarket pistons and have more on the snow just based on the amount of people running them who have posted on the forums. Many Polaris dealers (4 very good dealers I know of) have become dealers for the Fix Kit so that should lend even more credence. At least it does with me. In my conversations with 2 of them, the only time they will use an OEM piston is when they are doing warranty work.
Mike, I had the same opinion you have with regard to the concern of running a forged piston (especially a Weisco) in this motor. I have never been a fan of a forged piston and never thought I would see the day that I would use a Weisco. I went with the fix kit in my Dragon but I was very hesitant and leary. In fact, I was trying hard to get a kit from Terra Alps who uses an OEM Suzuki piston (cast) with his billet head and a cylinder shim. His kit was advertised within a few weeks of the fix kit coming to market. Just never could get my hands on the product.
I have been amazed (almost shocked) of how the fueling requirements in the CFI-4 were so much better AFTER the fix kit was installed. I did some very deep testing with EGT and AFR gauges, checking wash, closely monitoring and documenting data, (I'm an anal nerd with this kind of stuff sometimes) The runnability is way better, the power, the torque, the feel and sound of the motor. I have installed 3 kits on CFI-4's and 2 kits on CFI-2's. All have never run better.
My only complaint with the fix kit is the piston pin caged bearings are not included and must be purchased seperately. IMO, this should be included in the kit and bill us as such. I would never re-use one.
Dave, I know that of what is currently out there that uses a stock cylinder casting the fixit kit is the best..but man do weisco pistons scare the holy bjesuts out of me...My hope is the person I knows gets mad enough to produce pistons from said maker..they put everything else on the market to shame as far as pistons go...on the poo motors it comes down to figuring out how much wall clearence you have to have to keep it from scuffing on those long pulls, while still keeping a tight enough bore when its cold..very hard to do with a silicon based piston ......I dont think peeps realize that both the cylinder and the piston are expanding/contracting at sizeable rates...cylinders are normally more stable then the poo's are..(read more metal thruout, better coolant flow around the exhaust)..thats why the companies that are replacing the mono cylinder with aftermarket cylinders are solving most of the issues..cylinders arnt moving around as much as stock, stay rounder then stock during a heat cycle, and just hold onto the piston wall clearence better...hopefully this new cylinder for 13 helps with controling the cylinder better.....
So would hypereutectic be the best choice for a sled because it expands similar to a cast but shares some of the clearence characteristics of the forged? Who makes these for the 800 CFI2? What type of piston does the MTNTK Fix Kit use? What type are RKTs replacement pistons? thanks...
currently..from what I have seen..all sled pistons regardless of maker use a silicon based aluminum..(has lots of expansion)..hypereutectics still expand more then a good cast piston..its a fine balancing act..there is a thread on long rod motors that has more questions answered about pistons and such in this motor..might be a good read to better understand all the issues...
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INDEEP
Well-known member
If you still have warranty couldn't you just re nik the cylinders to proper tolerances with a new set of OEM pistons? It's not the cheapest option but your warranty would still be intact. There's nothing wrong with the Polaris pistons when they fit without excess clearance.
