2015 Pro RMK 800 Idle issues.

[IdahoSledder#09062006]

I have a stock 15 Pro RMK 800 with Carls Cycle clutching. Never had a single mechanical issue in 2 seasons. Been riding every day with no issues for 5 straight days now and on my way home this evening the sled started to idle very rough and wanted to die (Decided to tow it and avoid damaging anything further). I could keep it going with a little throttle but would die with no throttle input. I could restart it with a little throttle input while pulling but sounded horrible… (only tried once and only keep it running for a few seconds before I let it die again) Engine was not hot, temp was in the low 130s coming back on the last bit of trail. Normally it sits right around 120 when I’m playing in the pow all day.

Anyone have an idea what could be causing that?


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[IdahoSledder#09062006]

We did get gas and then stop for dinner, then finished the trail ride home. I always run 91 non ethanol. And it was the same station I’ve been getting gas from all week. Don’t think it’s bad gas but thought I would include that part as well. Also just tried to restart it after sitting for an hour in the cold. Fired up with throttle input but still won’t turn over without it. And still sounds like ****, like it’s shuttering almost and lacking power, not boggy though.


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[mtncat1]

check for piston or cylinder issues a comp test and some new plugs would be a good starting point

 

[IdahoSledder#09062006]

Finally got it home and did a compression test. 5 pulls, WOT on both sides. PTO side was only 76 and MAG side was 96. From what I have read, most people say 125 is good for these motors. What would you guys recommend I check first with my compression being so low and difference between the two sides? Thanks in advance for any help


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[IdahoSledder#09062006]

Took the head off and…not good. Any ideas what could cause that kinda damage?


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[IdahoSledder#09062006]

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[IdahoSledder#09062006]

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[retiredpop]

It definitely ate something. Is that a chunk missing from the cylinder port?

 

[Spiderman]

Sure looks like that same chunk missing is sitting on the top of the piston

 

[05rmksteve]

Did a ring locator pin come loose from the piston?

 

[IdahoSledder#09062006]

It definitely ate something. Is that a chunk missing from the cylinder port?

Yes, guessing that is what did the damage!


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[IdahoSledder#09062006]

Did a ring locator pin come loose from the piston?

New to this whole 2 stroke rebuild thing. Not sure I know what a ring locator pin is?


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[retiredpop]

It is a pin that is in the ring groove of the piston which stops the ring from spinning around. When the ring is installed the ends of the ring are on both sides of it.