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2015 Pro RMK Piston/Cylinder Scoring

R
Jan 4, 2017
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These pictures are from a 2015 Pro RMK with only 400 miles on it. I am wondering if anyone has an idea as to what would cause this type of wear so quickly? Poor compression 90psi MAG / 70 psi PTO is what led us to pull the jugs and inspect pistons/cylinders.

I noticed right away that the pistons/cylinders looked dry and were not getting enough lubrication. I am going to check crank run out and inspect case for any damage. If the lower half is ok will a hone/replate fix the damage to the cylinder?

Thanks in advance to any reply's. This is my first post on SnoWest and I appreciate all the information you guys post on here.
 

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Octanee

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I'd guess lack of lubrication, looks like some aluminum stuck to cylinder wall who his a good sign of that. Supposedly the sleds. Are way lean from the factory, I turned my pumps up so I seem to be around 35:1 or richer.
 

Vincenthdfan

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Dec 22, 2008
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Read up too on oil caps not venting properly.

They can create a vacuum and starve motor of oil too...lots and lots of reading in your future. (Been there, done that)
 

SRXSRULE

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It could also be cold seize related. You need to let these engines warm up to 100-110* everytime before you even try and move the sled.
 

gtwitch

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Jan 24, 2011
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Ditto on the warm up and possible cold seize, I like at least 45 to 55 to one ratio on fuel to oil. I had 55:1 on my 11 pro after some issues and it is happy with its new owner now!!
gtwitch in wyoming
 

NapaMatt

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Mar 13, 2009
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X3 ON Warm up!!!

Yes the do run, or move if you hit the ran after they are running... Doesn't mean.. she is ready to rip.. got to warm her up.. slowly ... then she will scream later!!!

wait till u see the temp come up to 100 before moving!!
 

rydningen

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May 9, 2009
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What pistons, stock or aftermarket forged? Seen a few seized forged pistons, definitely not as forgiving as the stock cast ones.

But, oil starvation might very well be what caused this. Vent oil cap, change fuel filter, replate cylinder, get some stock pistons to put in it.

Should be good to go:)
 
E
Jan 15, 2015
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Mine looked similarly bad after <500 miles on some SPI pistons after new cylinders and the oil pump turned up to the appropriate level and additional oil put in the gas tank. I'm extremely careful about not going much above idle until the sled is above 110 degrees, long/slow warmups first time in the morning also. Still trying to figure out what happened as the plugs looked fine.
 

RMK900Tractor

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It's difficult to ever truly get to the root cause of the problem. I want to mention fuel condition. After my last piston seizure, I noticed my gas tank had water sitting at the bottom under the gas. I removed the tank, drained, flushed, etc..

The day before my piston seizure while out riding I noticed the clear plastic cap over the fuel gauge was gone. We sealed up with a zip tie and a sandwich bag but I suspect snow had already gotten inside. the next morning was very cold so suspect the water made its way into the injector and froze causing a lean condition
 
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