Help :( Think I melted down a cylinder 2002 SRX 700

[mustangmatt]

Hello!

Just got back from a trip up to the arrowhead in MN. Trip was cut short as the sled all of a sudden lost power and died on the trail. The fiance was riding it. She said the "button didnt make it go as much anymore". Anyways I was able to rock the clutch back and forth to loosen it up. Pulled plugs, PTO and Mid cylinder were fine, Mag cylinder had aluminum all over the plug. Coolant looked low but seemed fine before we left. We had one small trip when we got a ton of snow to the south and ran fine then, before this trip I cleaned the carbs before we left too( to the south trip. After the south trip I did notice that on the trailer it seemed pretty hard to pull, I was able to get it to run and it ran fine or so it seemed. After getting the sled freed I was able to start it and limp it a few more miles to Finland MN. I rode back solo on the Apex (which I am now also having problems with, blew a belt and secondary looks like its missing a piece but that's another sob story and thread). I picked it up with the trailer and brought it back to the cabin and have not cracked it open yet. I've been around sleds a very long time but my brother has always done anything "engine" related and left all the suspension and other stuff to me. I have a lot of mechanical ability (can pull engines, heavy line on cars etc). Just have not torn a snowmobile motor down very far (have completely rebuilt car engines though). Basically what I am saying is Im not afraid to do it just looking for a bit of guidance as my bro is over an hour away from me and tough for him to find time to look at stuff anymore.

Cliffs-
Lost power
Found metal on spark plug of Mag cylinder
Coolant was low but not totally empty
Still runs on 2 cylinders
NO Compression on Mag cylinder, at least not with finger
Looking for how to's, advice, vids, manual, anything to help tear and repair
Other things to look for/repair that might have caused this...

Thanks a ton in advance fellas This is the first Yami motor I have ever blown up and a bit sad over it!

 

[mustangmatt]

Also the fiance said she saw no lights. When starting the sled I would get 3 blinks with both the Temp and the DCS light, I thought that was a bit weird... Thought I should note that too...

 

[SRXChris]

Light should blink 3 times when started. By the sounds of it I experienced the same issue as you. Motor needs to come apart and inspect it. You will probably find a bad piston or rings gone. Drain coolant and pull heads off and take a look and report what you see.

I posted some pics of mine.

 

[RXMax]

POST pictures of the piston on the burndown cylinder. That will tell a lot.

 

[drew24]

If there is aluminum on the plug you definitely burnt a piston. It could have been running lean from a carb problem or bad crank seal although I am not sure if that would set the dcs off or not. If it were me I would check the carb good for a plugged pilot and check the screen under the float valve and check the fuel filter in the tank to see if there is something definitive that could have restricted fuel flow. If that is all good I would change the crank seals. I would do that anyways just to be sure. They are getting old. Also check (If it isn't destroyed) the pins that hold the rings in place. If you can do car engines these 2 strokes will be a piece of cake. They are the same but easier. I was in the same boat about 5 or 6 years ago.