Popped 800 Mag side piston!!

[freeride73]

My friend was riding his 2013 RMK Assault 800 yesterday. Filled it up with 91 from Costco. Was about -25 C, he let it warm up for about 10 min. Rode slow at first then it just stopped once he started riding. He thought it might have been water in the fuel tank. Got it going again but had no power. Took it apart and mag side piston was scored. Plug was quite white (Lean). So we will rebuild the top end. Any thoughts on what might have caused this? What is the bust fix with pistons? Is this common with Poo's. He only has 600 miles on it and this is our first year with Polaris.

 

[Audette13]

i don't own a pro,so i am unfamiliar with warm up times(i do have a dragon and i know i am the last guy to move after a cold start).

but warming up for 10 min when its -25C just doesn't seem long enough to me (im assuming it was sitting outside over night)

seems like most pro's are getting to the 2000 miles mark before issue( my buddies 12 assault just took out a crank at 2100 miles)

cant go wrong with MTNTK fix

 

[BILTIT]

Search "Fix kit", rec supply sells one. In fact, its on their home page right now.

 

[Kyper]

I have a 2012 Pro RMK, I just had my engine replaced on warranty, counting the factory, this is the third engine this sled has seen.... First engine the dealer could not tell me what caused the failure!! The second one I road it till it threw a rod through the block, I got a Polaris crated engine installed this time, the dealer said lack of oil... even though the oil level never got below 2" from the top of reservoir. The local Doo dealer gave me a 2013 Summit to Demo, after 2 days I took it back. I rode my friends new 800 Freeride 2 days ago. All I can say is even with my engine problems I will not own a Doo. Those sleds are horrible to ride compared to my RMK.....

 

[+SLEDWRECKS+]

Just had the same thing happen on buddies 2011 pro last week. Sled was in a heated shop to begin with.
It was cold seized and locked up the engine. Got it free'd and limped it home, 38psi compression mag & 120psi PTO side
It was -24C out and had not warmed it up enough and was on the throttle. I think the thermostat open's around 48-50C. So if the sled is not up to temp, and you head out pinned across a field, once the t-stat opens up your engine gets a full shot of cold coolant from the tunnel exchanger & squeaks the mag side of your engine. Damaged the cylinder as well so requires a monoblock. PTO side is fine, and this sled has 3400kms on original pistons and nitrous........descent milage for a poo. Plus we have always added extra oil into the fuel tank.

 

[gbollingberg]

Same thing just happened to my 13 pro. Has 400 miles on it and about 60 lbs on mag side. Happened about 20 mins into my ride. It should be covered by warranty and is going in on Monday so weel see what they say.


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[RK Tek]

Just had the same thing happen on buddies 2011 pro last week. Sled was in a heated shop to begin with.
It was cold seized and locked up the engine. Got it free'd and limped it home, 38psi compression mag & 120psi PTO side
It was -24C out and had not warmed it up enough and was on the throttle. I think the thermostat open's around 48-50C. So if the sled is not up to temp, and you head out pinned across a field, once the t-stat opens up your engine gets a full shot of cold coolant from the tunnel exchanger & squeaks the mag side of your engine. Damaged the cylinder as well so requires a monoblock. PTO side is fine, and this sled has 3400kms on original pistons and nitrous........descent milage for a poo. Plus we have always added extra oil into the fuel tank.
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Take a look at your ring land area on the failed piston.. I think youmay find that it has spread (top to bottom)..

Let us know what you find out..maybe post some pics

 

[LUCKY 7]

that's why I got 4 years engine warranty on my new 2014 pro.

 

[+SLEDWRECKS+]

Take a look at your ring land area on the failed piston.. I think youmay find that it has spread (top to bottom)..

Let us know what you find out..maybe post some pics

I will get some pic's when we remove the pistons. Just waiting on a rebuilt block to show up in 7-10 days.

 

[catalac]

Four corner sieze.

 

[Chrisco]

I will get some pic's when we remove the pistons. Just waiting on a rebuilt block to show up in 7-10 days.

Where is it coming from.....thats like next day from me.

 

[BrianP]

I have had this problem many times on different sled's, I will not use ethonal gas any more. I only use shell or esso 91 octane, I was told by a 2 stroke engine builder this tip and ever since then I have not another piston. Shell and esso 91 octane do not contain ethanol at all just the 89 and 90 do.

 

[Black Rhino]

Is this machine modified in any way?

My friend was riding his 2013 RMK Assault 800 yesterday. Filled it up with 91 from Costco. Was about -25 C, he let it warm up for about 10 min. Rode slow at first then it just stopped once he started riding. He thought it might have been water in the fuel tank. Got it going again but had no power. Took it apart and mag side piston was scored. Plug was quite white (Lean). So we will rebuild the top end. Any thoughts on what might have caused this? What is the bust fix with pistons? Is this common with Poo's. He only has 600 miles on it and this is our first year with Polaris.

 

[freeride73]

This is a stock sled no mods!

 

[andrew3399]

This is a stock sled no mods!

Being a 2013 no warranty? Did he not pay the extra 300 for second year?

 

[freeride73]

no warranty

 

[slededjr]

Esso has ethanol in all their fuels.
Do you know what engine temp was?
Maybe got bad gas from the costco?

 

[sweld]

Esso has ethanol in all their fuels.
Do you know what engine temp was?
Maybe got bad gas from the costco?

Not in there premium


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[slededjr]

Yours is special then. The one beside my house here says up to 10% in 87 and 89, up to 5% in 91. Esso in swanhills says ethanol too. Station specific maybe?

 

[slededjr]

According to Esso website I would think it is station specific as it says ethanol blended fuels are available at participating stations. Must be up to the owner to decide I guess. Good to know. I've never had any problems with ethanol fuel anyway. As long as it's fresh and not going to be stored too long it's OK. Will always choose ethanol free though if the option is there.