Blown up Viper - questions for the pros

[YamyMan]

Last winter I was riding down the trail straight away and sled died on trail. The center plug had all chunks of metal on it and it looks like the gap was almost closed. The center piston has all chunks sitting on top of it around the perimeter. Try to post pictures later. Wondering what happened. I can still cycle the engine, it is not ceased up.


Maybe it got too hot? What should I look for to find root cause? Any help is greatly appreciated.

 

[dirtjumper895]

Im guessing, possibly a lean jetting issue. Does the piston look like it is melted more on the exhaust port? Also, post pictures of the other two pistons tops, as we may be able to detertmine possible jetting conditions by looking at piston wash on the other cyclinders.

 

[mopar1rules]

i'm guessing your lower rod bearing let go on that center rod. common on vipers. all those chunks on your piston crown, are pieces of the rod bearing that got sucked up thru the transfer ports.

 

[sledr3405]

You said you were cruising down the trail?
From what i know, 90% of the time vipers blow in that type of riding ( assuming you were jetted somewhat close) is caused by the huge lean spot in the mid-range. Thats why you gotta blip that thottle. Thats my 2cents.

 

[Cam/ Viper adict]

Pics would help.. I had a similar experience with my viper and the cause was a bearing on the crank. It just slowed down and shut off. I could still pull it over because the bearing didnt seize entirely. But still pics would help everyone..

 

[tcdesignguy]

Sledr3405 makes a good point there is a spot in the ignition timing curve that if you happen to stay at that point too long, it will go down.

 

[Sno-Xr]

Long story short, there are many things that will cause what has happened the way you described.(lean, broken ring, bearing failure, piston skirt.... etc) Pics and more info will be needed, but in the end, you will have to dissasemble the motor to get the answer you are looking for.
Good luck
Sno

 

[YamyMan]

Thanks for the help so far. I am going to have to tear it apart some more. The center piston has chips out of it around the top perimeter. Looks like the top of the piston is just crumbling to pieces around the perimeter, mostly on exhaust port side, but it is all the way around. The piston is all white on top around edges. There is a build up of what looks like aluminum on the bottom side of the head. Jetting is all stock.
Have pictures, but need to shrink size down to post

 

[YamyMan]

The bottom of the picture is the exhaust port side (front of engine). The whits area is all pitted on top of piston
The other pistons are brown color

 

[YamyMan]

Here is the piston on the pull rope side. The clutch side looks similar to this.

 

[YamyMan]

Better pic of center cyl

 

[mopar1rules]

Here is the piston on the pull rope side. The clutch side looks similar to this.

you don't have any piston wash. jetting must have been a little lean, but the vipers and many other sleds have a lean spot in the midrange, where when ran there for a long period of time, bring egt temps up high and motor goes to hell. '05 800 ptek ski-doos are notorious for this.