Blown sled!! Please help

[Maxdragon]

Hey.
My neighbors 2005 Polaris edge touring deluxe 550 fan blew this past winter when his friends took it for a ride. they were probably going anywhere from 20 to 35 mph and then it died. I was able to get it going again and it drove another couple thousand feet before making a clunking noise and dying. After that I couldn’t even pull the pull cord on it. When I pulled it apart I found one terribly blown piston basically melted in areas and a big hole in the top. Any idea why it would have blown?
Thx everyone

 

[AkRider217]

I've blown two sleds now. Both times it was from severely overheating them on a hard pack day. One was a fan cooled and the other was a liquid cooled. I'm sure there are quite a few ways for an engine to blow but if the piston is melted it probably overheated. But to really know if this is the case we would need to know the snow conditions that day, outside temp, and how hard they had been riding the sled.

 

[BeartoothBaron]

Cold day? What do the carbs look like? I've got an old 440 fan that burned down a piston because it was jetted for 10K' and was ridden at 4K'. Could be bad jetting or a partially blocked jet in the carb. Take a good look at the carb boots and crank seals too: they'e another common cause of burn-downs. There were some issues with the 550 in the EDGE chassis too – do a search on 550 burn down. Can't remember many details, but sustained part-throttle riding seemed to be where it happened the most. Definitely something to get to the bottom of and correct when you rebuild.

 

[Maxdragon]

I've blown two sleds now. Both times it was from severely overheating them on a hard pack day. One was a fan cooled and the other was a liquid cooled. I'm sure there are quite a few ways for an engine to blow but if the piston is melted it probably overheated. But to really know if this is the case we would need to know the snow conditions that day, outside temp, and how hard they had been riding the sled.

My friend that was riding it said it was a cold day and the trails were packed hard. They weren’t riding it hard. Probably anywhere from 15 to 35mph on the packed trails.Thanks for all the info!

 

[raleigh111]

550 fan cold day probable not overheated unless fan belt blew or problem with fan
look at the carb that blew, check intake boots crank seal. is it sucking in air. main jet pilot jet clogged. how was it running when blew? did it idle fine? if you don't find cause it will blow again.

 

[whoisthatguy]

The oil injection tube in the carburetor can get clogged. Which can cause a burn down within a half mile from the trailer. The engine probably initially sustained some ring damage that also damaged the cylinder walls. Which tends to cause an automatic shut down. Further running could have produced metal that damaged bearings. The sled is totaled and is most likely not worth repairing the engine. Any other engine that you drop into it, will probably also be suspect unless it was running last year. Engines that sit around after being pulled, tend to develop some corrosion somewhere, that then causes another rapid engine failure.