Looking at a possible upgrade from a 2up machine to a single rider. Lots of Polaris 800's out there with 'fix kits' done. They were done from around 2008 to 2012. Right in the sweet spot for a cheap used machine. Avoid them? Look at a 600 instead? Any advise about what to look at when looking at these would be appreciated.
Polaris 800 Fix Kits
- Thread starter nast70
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007sevens
Active VIP Member
The fix kit was a must and made the engine ALMOST bullet proof. I have a 2011 that I put a fix kit in and its running strong with 2500 miles on it. Compression still about 150 a side. I wouldn't be scared of a sled with the fix kit in it, I wouldn't buy one with out.
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Quicksand
Active VIP Member
Just sold my '12 with over 5400k on it, no fix kit, just pistons when they should be done
Are the fix kits necessary though?
Good writeup by Indy Dan
https://www.snowest.com/forum/archive/index.php/t-433563.html
Good writeup by Indy Dan
https://www.snowest.com/forum/archive/index.php/t-433563.html
AxysAssault
Active VIP Member
Had a 2009 dragon 800 136" with 3500 kms no fix kit. Had it ....never installed. Compression was 145 if I recall.
Buddy had the rmk version.......4th rebuild.
Buddy had the rmk version.......4th rebuild.
Quicksand
Active VIP Member
I don't believe they are "needed", it's just common knowledge the 2-strokes are hard on pistons. yes the fix kits work, yes the long rods work, but when you do them you're changing out pistons. I feel its the piston that needs changing, not the geometry of the engine. Keep fresh pistons in them and they run well.
Beels
Active VIP Member
How often did you change them?
Quicksand
Active VIP Member
Just once on that sled, at around 2200km, compression was starting to drop on one side, was still good when I sold it. I run my sleds a lot around home so probably 60-70% of the miles were not in the mountains. If you keep an eye on the compression and write it down, keep a log somewhere, as soon as you think its starting to go, do them. Pistons are cheap compared to cylinders and engines lol
mikol
Member
3000 KMs seemed to be the sweet spot for our group, at one time there was five pros in the group from 11-14 and three of them blew up right about that 3000 mark. Once fix kits installed there hasn’t been an issue since. Really great sleds otherwise!!
Quicksand
Active VIP Member
Quote taken straight from Indy Dan, and I feel the same way
"And ( NO ) there is not going to be an aftermarket piston that’s better then The OEM...... there never has been and never will be. The OE BUDGET is far past the aftermarket."
"And ( NO ) there is not going to be an aftermarket piston that’s better then The OEM...... there never has been and never will be. The OE BUDGET is far past the aftermarket."
Beels
Active VIP Member
I've got right around 2000km on my '12 and I haven't checked the compression for a couple years but I can tell it's starting to lay down a bit. I probably should be replacing them. Oil pump was cranked up early on and I run a bit of oil in each of fuel.
Teth-Air
Active VIP Member
If you ride hard, these motors wear. Even the 600 we had needed pistons after 2 years. Sure, turn up the oiler but sometimes it is not enough. My 15 just went down with piston failure and it had the oiler turned up 2 turns from new and 300 ml extra in the tank on this ride. Treat these motors like a 2 stroke race bike and consider new pistons just a "2 stroke tune-up" I would suggest every 2 seasons if you ride hard and get in 30 rides or more/season. Or do as I did and buy extended warranty coverage before the factory is coverage is up. I got lucky as first ride of the season and the motor went down so new motor is in now and I don't have to worry about rod bearings going shortly after just doing a top end. I have had a couple rod bearings go too and believe it is because I don't fog the motor in the spring. I expect condensation pits the bearings over the summer. I will try harder this year.
Beels
Active VIP Member
I've been starting mine every month or two and letting it idle for 10 or 15 mins. Done that with every sled I've ever had and have never had a problem.
RK Tek
Active member
But there can be better aftermarket crank bearings, rods and cylinder finish.. Just not pistons..right?
Canadiansledhead
New member
The fix it kits are miss worded for sure.
Any if you actually measure cylinder and new pistons?
wossener pistons with shim kit is 0.0065” clearance new or more. How is that fixing the problem when factory oem are 0.0055”? I realize there forged vs cast, but c’mon?
snake oil
Any if you actually measure cylinder and new pistons?
wossener pistons with shim kit is 0.0065” clearance new or more. How is that fixing the problem when factory oem are 0.0055”? I realize there forged vs cast, but c’mon?
snake oil
RK Tek
Active member
The fix it kits are miss worded for sure.
Any if you actually measure cylinder and new pistons?
wossener pistons with shim kit is 0.0065” clearance new or more. How is that fixing the problem when factory oem are 0.0055”? I realize there forged vs cast, but c’mon?
snake oil
I agree, if the piston has .0065" clearance when new, then it will have .008" after a shirt run time.. Not much better than stock.
If using a fix kit the cylinders are raised up off the bottom end of the engine so that the pistons can be made taller which in turn makes the piston more stable inside the cylinder. It is much less likely to slap/rock compared to the shorter stock piston.
As far a clearances go. Most aftermarket pistons seem to be forged. A forged piston will expand more when heated than a cast piston. Forged pistons should have more clearance do to the higher expansion when hot. Not so good for cold startup. They will also less dimensionaly stable when the engine is running as the temp of the piston changes according to engine loads.
[FONT=Roboto, sans-serif][/FONT][FONT=Roboto, sans-serif]A hypreutectic cast piston changes dimension much less than a forged piston and remain in tighter spec over varying engine loads. This mean less wear over time. Much less wear on cold startup.
A forged piston is stronger and good for very high stress engines but lower longevity is the the trade off.
I suspect most stock oem pistons may not be forged as they generally offer the best longevity. This may not be the case in these 800 engines though and could account for the shorter life of the pistons and cylinders.
"performance or upgrade" pistons are not always a good thing from my standpoint[/FONT][FONT=Roboto, sans-serif].
2008 Polaris Dragon 800 163"
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