Something has to allow or cause the piston and valves to come together. Over rev's, broken or damaged valve train drive are about the only two ways that come to mind. The damage was probably done awhile ago and just let go when they did. The joy of buying used. Just never know how the machine was used or abused. The previous owner may have know and just chose to sell it. Never know. Have not seen this problem on the forums so suspect it is a freak. We will see what others can add.

Might be the ideal time to go with the new HO kit.

 

Yeah, I kind of suspected that this may have been some kind of panic sale. But strangely, although the oil and water were mostly gone by the time I got home, there does not appear to be any lack of oil heat/wear/damage and thankfully, at this point, the crank feels fine.

and yes, I immediately thought about a big bore kit etc, but i'm a little gunshy at the moment....

 

Some of the 11's and early 12's had valve spring problems.
I'm replacing my springs and valves to hopefully avoid this problem on my 12.

 

I have read that. I searched and found s/n listings and mine wasn't in the list, but I have nothing official. Strange tho, if it was a soft spring situation that ALL four valves on one side are affected and none on the other. :/ At least that's where my liquor logic had me at about 3:30am this morning when I had it finally tore down.

 

http://www.atvicon.com/XP/1.jpeg

http://www.atvicon.com/XP/3.jpg

http://www.atvicon.com/XP/4.jpg

http://www.atvicon.com/XP/5.jpg

 

Lots of carnage there for sure.

 

......Tear down showed 1 cylinder ok, the other had 2 broken valve heads sitting on top of a very damaged piston. The other 2 valves bent bad. Cylinder wall cracked, head destroyed.......:

hmm....one piston going up and pow?

what if the cam chain jumped?

(just discussion - I'm still learning my engine)

 

......Tear down showed 1 cylinder ok, the other had 2 broken valve heads sitting on top of a very damaged piston. The other 2 valves bent bad. Cylinder wall cracked, head destroyed.......:

hmm....one piston going up and pow?

what if the cam chain jumped?

(just discussion - I'm still learning my engine)

Well, either cam would affect both cylinders (exhaust or intake). It's one cam per function, not one per cylinder -and I guess that's what makes it weird for me that the back half of each cam resides over the damaged cylinder, however, the single valve initial failure might explain this all away. I've compared the valve springs and I can't find a difference. I can't see floating a valve at 40mph so yeah... light the damn thing on fire and enjoy the bbq

 

yes sir. I'm looking at mine on my other screen; head on the work bench.

just for the heck of it check your hydraulic tensioner.

Takes all of 15 seconds to unscrew it. Inspect its condition. Any quality engine work would warrant its inspection before its time to fire up and hand back to the customer.

 

I'm tore down already - see pics above. Tension and tensioner were working as advertised. I did glance at the timing marks on the way down. All good. But yeah, again, if the chain was off enough to affect one cylinder I suspect it would affect both in the same way (assuming the cam is ok)

 

Serious damage from the pictures. Think I would replace the conn rod and bearings on that one side, since that is a high RPM engine. Heavy piston damage had to go down the rod as well.

 

Im really really trying to avoid splitting the cases, but sound advice for sure

 

yes sir. its worth discussion.
my tensioner would not hold a prime upon install of modded head.
If the machine sits a while that can happen.
My Tech overly cautious and installed a new one. There was tiny oil crap in my tensioner.

Everyone wishing you well.

 

Everything you need to fix your engine is currently listed for sale in the parts section right now.

 

my tech guy described what that tensioner MAY realize under normal operation. Its spring loaded. What gets me is the "fixed" style being sold. Those dont move.
Willing to learn here......

 

A number of automobile manufacturers use a similar type tensioner, it allows it to self adjust as the chain stretches and guides wear. The Ford 4.0 SOHC engines used this type, over time it would bleed down and sound terrible on start-up for a few seconds. I suspect the "fixed" type will require an occasional adjustment to keep chain tension correct.

 

One valve breaks at 5000 rpms, it will usually take out the piston and the head including the rest of the valves. The crank and rods are always questionable at that point. Good luck.

 

When I buy out Polaris and take over expect more tech videos and cutaways like that tensioner because I like cutaways.

Taking early applications for someone who can cut stuff open better than that.

(I'm the one who made that video)

 

I have dual 26" monitors.
Your photo on one screen and my head on the other.
Did that answer your question?

 

I have 3 22's and tried moving your posts from screen to screen, but no it didn't help.

 

Can anyone recommend a big bore kit?

 

I think Johhny from UTV Inc has a whole motor for sale......brand new, less than 5 miles on it. He took it out of an APEX built he was working on.....

 

Im interested. If anyone knows him and he does have such a motor could they hook us up?

 

Here is all the info on motor and how to contact Johnny------still for sale as of the 5th....

http://www.rzrforums.net/utv-inc/101407-2013-xp-engine-sale-soon-1-mile.html

 

Rage, when you removed your tensioner were you able to push it in at all by hand or on a counter? It should be rock hard and near impossible to push in.

Nate
Alba Racing

 

I couldnt move it and as i said i did look at the timing marks on the way down. Im getting convinced that either because of a soft spring or whatever, i floated a valve or lost a keeper and boom.

Sucks but c'est la vie

 

the xp has been prone to valve and cam proplems you see it all over and yes alot have gone to a manual adjuster

 

Thank you. Callin now.

 

The Exhaust guides go bad in the XP heads. Contact Curtis Sparks. He has a fix for the guides.

 

Yeah I need more than guides at this point lol, but thanks

Talked with the boyz at UTV about that motor - they still have it but $3500 is a little high for me. I priced out pistons-up including cylinder and head at Polarispartsdealer.com for $1400 (ish) - anyone deal with these guys before? Price sounds reasonable.....

 

Interestingly, I was adding parts to the shopping cart at polarispartsdealer.com and there's a substitute / new part number for the valve springs (angryface)
Anyway, all new valves, guides, springs, seats etc new head, new cylinder, new pistons/rings clips pins bla bla bla - $1500. All of a sudden that's not such a big bummer.

Oh - and my truck looks like just a CV - and its sunny out...........

 

Anyone changed a rod up the pan? (still trying not to split the cases)

 

Well, checked for recalls today on my machine - none Called the dealer I got it from - Xtreme Powersports in St. Paul Alta - let them know I got 45 miles on the unit since i bought it. It was used, but we'll see if they want to help out or not. They seem pretty good, but that's usually when the money flows in one direction :/

Thinking I can get the oil pan off without pulling the motor......

 

your motor comes out easy and you might spot a thing or two making that a wise choice.

then again if the motor comes out next thing you know you stiffen the frame, improve the shock mounts and ten other things.

 

ya and split the cases so I may as well stroke it and do the bearings and...................