Piston Failure Diagnosis.

[xTonyCRx]

Well I guess I have to keep checking my pistons via the VES ports. If there is a mechanical/electrical issue that caused the burn down I hope it shows itself again before warranty is up.

I'll be adding some oil to the tank until the warranty is up then I will be turning up the oiler.

If detonation due to bad fuel caused the issue I'll have to switch brands because I cannot get any better fuel than what was running and what I have always run.

I did not miss a weekend and the sled is working great although after about 200 miles it quit and leaked fuel everywhere. I found one fuel rail bolt had broke and the other backed out all the way. I suspect it was over torqued.

 

[2XM3]

just a fyi, we regulary test fuel (friend has a really high dollar dilectric tester) found 91 pump from 83 to 91 octane ...tank to tank ie pupm gas is pretty much crap these days

 

[xTonyCRx]

just a fyi, we regulary test fuel (friend has a really high dollar dilectric tester) found 91 pump from 83 to 91 octane ...tank to tank ie pupm gas is pretty much crap these days

Exactly, my point is that I cannot control the quality of fuel available to me so I need to find something that will not self destruct when it burns less than perfect fuel. Although he has experienced other issues, my friends AC 800HO had no problem with the fuel we were burning that weekend.

Just as a note, this is the first time I may have every had any fuel quality issues in my area.

 

[pura vida]

it may or may not have been the fuel. pick up some torco octane boost if you are concerned about your fuel quality. i would also recommend turning up your oil pump. first thing i did on my 13. i put 5 full turns on mine and am running right around 32:1 now. tells you how lean it was set from factory... it is a 2-stroke. they need oil.

pv

 

[skibreeze]

You didn't state whether or not you are running the ethanol plug or not. I don't understand you resistance to turning up the oil pump, it is a simple adjustment and adding oil to the tank does nothing for the crank.

 

[geo]

If a 2 str doesn't get enough oil the cylinder walls and bearings (particularly both the rod bearings) have less cushioning and lubrication on them and the rings don't seal as well.
If the rings don't seal as well blow by will happen sooner and this adds to the friction in an already marginal situation on the cylinder walls and bearings. Friction adds heat, compounding the above case senario and eventually the motor just gets tired of it and fails prematurely.
To run for 3200 miles at this ratio is a testament of the durability of this engine. Makes me happy and comfortable to know what mine will look like inside at only 1200 miles cause she's had 32 to 1 and enough fuel to at least color the plugs since the day she was unloaded on the snow.

The possibility of a mechanical failure of another part (that led to the failure) has not even been eliminated yet. This makes me even more comfortable with my 800 liberty motor.

 

[xTonyCRx]

You didn't state whether or not you are running the ethanol plug or not. I don't understand you resistance to turning up the oil pump, it is a simple adjustment and adding oil to the tank does nothing for the crank.

All premium here is non ethanol so I run the premium plug. I have thought about cranking up the oiler but with the paint mark from the factory I worry that I would be giving Polaris a reason to deny a warranty claim. It seems like they look for any reason to deny claims. I have mentioned it to the dealer but they didn't want to adjust it for me stating that it was set properly (marks lining up).

I might just do it anyway after I pick it up tomorrow night.

 

[skibreeze]

I'd run the ethanol plug regardless, extra level of safety.

 

[pura vida]

there is no way they could reasonably deny your warranty b/c you had turned up the oil pump. warranty claims can be greatly effected by the dealer. if you get any friction from your dealer about this i would look of another if at all possible. not attacking your dealer in any way as i have no idea who they are. they may be the absolute best there is, just speaking from personal experience. i am so thankful i have the dealer i do.

pv

 

[wellfed777]

"My 2012 Switchback Assault recently went down with 3200 miles."

well i'd consider my self lucky to get 3200 miles on a set of pistons in a sled !
luckly you didn't kill the bottom end
after 2000-2500 miles i'd be thinking top end on any high performance sled
engine call me crazy i agree with others more oil would be a good idea

 

[xTonyCRx]

"My 2012 Switchback Assault recently went down with 3200 miles."

well i'd consider my self lucky to get 3200 miles on a set of pistons in a sled !
luckly you didn't kill the bottom end
after 2000-2500 miles i'd be thinking top end on any high performance sled
engine call me crazy i agree with others more oil would be a good idea

These miles are flat land miles with probably 50% trail and 50% off trail. Even the off trail riding we do wouldn't compare to the abuse a sled would take in the mountains.

I had full intentions of throwing a Drop In kit next fall.

 

[Greg16]

I have seen that exact same blow up on my 10' 600 rush and my 12' 800 pro r. That's not from detonation it is from the top ring catching the exhaust port on the way by. Once these motors get some miles on them for whatever reason the ring groove in the piston will grow to the point where you could fit two rings where one should be.

I have three riding buddies who also have 12'-13' 800 polaris's and once mine failed it prompted them to first do a compression test and once that turned up on the low side of good. They pulled their Y pipes off to get a closer look. All of them found that their rings had way more play than they ought to.

The mileage of the four sleds (mine included) was from 1500 to 3000.

Now this is just a theory, but what I think is happening is the excessive piston to cylinder wall clearance that exists in these motors is causing an excess of stress on the rings. Basically using them as a hinge point.

I have been talking to my dealer and since mine failed, he looked into it and this exact same condition is rearing its ugly head at all of the other dealers in my area.

 

[96sherm]

Do yourself a favor and look into your bottom end seals. My motor went down at 2400 miles, I was going to do top end only, but the state of the pistons made me curious as to how they became so damaged without somehow sucking in some snow or something. Turned out that my PTO side bearing cage had departed and wrecked the PTO side crank seal, sucked in snow and poof, cold seize... You're down anyway, might as well look everything over to be sure!!!

 

[wellfed777]

tony
ok i hear ya but honestly trail miles can be harder on a sled engine sometimes
i still think by 2000+ miles i'd be looking up that Ypipe
ha ha at the pistons but i'm not an engine builder its just my opinion

 

[800poodragon]

I have a 12 Pro...pulled my cylinder last Oct and found my rings were flaking bad on the intake side. I believe the injector washes the oil from this spot so I now mix oil in my gas as well as my dealer turned up the oil injection. My sled only had 700 miles on it then. I see this year on sled rumors they say the rings are improved on the 14's....I wonder if this is what they are improving on?

 

[xTonyCRx]

Do yourself a favor and look into your bottom end seals. My motor went down at 2400 miles, I was going to do top end only, but the state of the pistons made me curious as to how they became so damaged without somehow sucking in some snow or something. Turned out that my PTO side bearing cage had departed and wrecked the PTO side crank seal, sucked in snow and poof, cold seize... You're down anyway, might as well look everything over to be sure!!!

My sled is still under warranty and I did question the dealer in regards to bad seals leading to the failure. They assured me that was not the cause, although I do not think they did a leak down test. The sled is back on the snow now, without even missing a weekend. I have put about 450miles on it since the failure. I will be replacing my top end with a "fix kit" before my warranty expires in February 2014 that way if I find any other issues (bad cylinder, crank, etc) I can get the dealer to foot the bill. I will be doing a leak down test myself before dis-assembly. If I find any faults (leaks), I'll be dropping it off at the dealer.

tony
ok i hear ya but honestly trail miles can be harder on a sled engine sometimes
i still think by 2000+ miles i'd be looking up that Ypipe
ha ha at the pistons but i'm not an engine builder its just my opinion

During preseason (2000 miles) PV cleaning I inspected the pistons. There was no scuffing or excess ring land gap at that time. I had planned on doing the PV's again mid season but it let go before I had the chance.

It has been running well since the rebuild...

 

[xTonyCRx]

I have a 12 Pro...pulled my cylinder last Oct and found my rings were flaking bad on the intake side. I believe the injector washes the oil from this spot so I now mix oil in my gas as well as my dealer turned up the oil injection. My sled only had 700 miles on it then. I see this year on sled rumors they say the rings are improved on the 14's....I wonder if this is what they are improving on?

As far as I can tell that website is all BS, he was pretty much wrong across the board with his predictions.

 

[GoBigParts]

My dealer showed me some pistons that looked the same way. This is usually where they break. One would think it is due to poor design and to much piston to cylinder clearance. You get a piston slapping around in there enough stuff is bound to break. I believe this is why RK-Tec has a drop in piston and indy Dan fixes clearance issues.

Mine has 2400 plus miles on the stock motor right now. Ethonal resister plug always, and mine never had oil pump turned up. Don't need to I seem to be using plenty of oil.

I looked through my valve port and it appears my ring slot is starting to open it up slightly on the exhaust side. My dealer has already ordered the new pistons for me. Does this fix any design or tolerance issues? Probably not.

 

[seth25]

Do yourself a favor and look into your bottom end seals. My motor went down at 2400 miles, I was going to do top end only, but the state of the pistons made me curious as to how they became so damaged without somehow sucking in some snow or something. Turned out that my PTO side bearing cage had departed and wrecked the PTO side crank seal, sucked in snow and poof, cold seize... You're down anyway, might as well look everything over to be sure!!!

I think you may be a bit confused as to what "cold seize" means...

 

[The Fourth Wolf]

I don't understand you resistance to turning up the oil pump, it is a simple adjustment and adding oil to the tank does nothing for the crank.

Disco...