What could of caused this on my 95' XP

[JKSTI&R1]

Hey guys,

Ok so im doing the top end of a few of my ski's ( 95 xp and gtx ) and I had what looks to be the same damage on both ski's from the same side cylinder ( front of the ski one, the mag side right? ) The skis are from different owners from different states, so different riding conditions. So why did this happen? I took the piston the the shop that is boring out my cylinders and they said it might be from a few different things. I said maybe got to hot and had lack of fuel or oil. They said maybe but if that was the case, most of the time the top of the piston will be burnt or something and he didnt see that. So what do you guys think happened? I want to fix the problem so it dont have to do the top end again if its a bad oil pump or clogged carbs or what not. I pulled the carbs and they look clean so far. Havent been able to get the fuel side of the carb off just yet ( was on was to tight ) but will be re building and cleaning them, but they look super clean so far.......:facepalm:

 

[LouDoo]

Do you still have the grey tempo fuel lines on both ski's?

Lou

 

[Robj]

To my amateur eye it looks like oil starvation.

 

[AdamXP800]

I would agree, to my amateur eye it looks like extreme oil starvation

 

[JKSTI&R1]

Do you still have the grey tempo fuel lines on both ski's?

Lou

At first glance, no there are black lines but after I pulled the jugs and the carbs off ( very clean but the filter had like sand and little things in it, going to clean carbs good, new filters and diagrams ) they left the grey line where it looks like they couldnt reach or get to easy. I have new goodyear 1/4 fuel lines and I bought new lines for the oil pump. Do you think the oil pump is bad? I heard from tons of people that it almost never fails because its on a cable.......

 

[griz400]

looks like a lean seizure and over heat condition, was lean run and whoever had it kept firing it up and over heated cylinders bad, like lou suggested, gray fuel lines ??? gunk in carbs ???

 

[JKSTI&R1]

looks like a lean seizure and over heat condition, was lean run and whoever had it kept firing it up and over heated cylinders bad, like lou suggested, gray fuel lines ??? gunk in carbs ???

Not 100% grey lines but there is still feet of it in there. I will be changing that out. No the carbs are very clean to my surprise.........

 

[griz400]

do you have oil injection on it, or premix ??? also, under the skirt of the piston, is it wet with oil ???? cause if you have injection hooked up, and under the skirt has oil, then for sure it was a lean seizure, and he just kept riding it

 

[JKSTI&R1]

It is still injection from what I know. everything looks right and there. The bottom of the motor ( the crank shaft ) had oil and looks clean but under the pistons are dry but black, like there might of been wet oil at one point but the skis may have not been rode in maybe a few years on one and the other maybe not since 05'. This is a picture of the pistons. they are the damaged ones from both skis ( not the same pistons out of the same ski, one is from the xp the other is the gtx ) The piston on the right is out of the gtx and the one that I have pulled the carb out and the carb is clean with some stiff in the filter. it has some grey lines still, but not for long. The one on the left is out of the xp and I have not pulled the carb off yet and im sure there are grey lines as well..........

 

[griz400]

when i tear one down, like you have, i evaluate whole motor, if it is oil injected, and 1 cylinder fails, and other one looks real good, chances are the pump didnt fail, maybe a hose cracked and no oil to cylinder, but as i said previous, if oil is under piston skirt, then was due to a lean out -- its called a lean siezure, now, you just got these skis, so on a overhaul, i would put new oil, oil lines, and oil filter, along with carb overhauls ....i wouldnt trust oil thats in the tank, just put all new oil ....


oil lines are 3/32 tygon line, any big lawnmower repair shops have it, like 1.50 ft and each ski, maybe 4 ft

 

[JKSTI&R1]

Ok. I did get new oil lines from the ski shop and I will drain and clean the old oil out. So what you are saying is it ran with no fuel and just oil. That would be running lean, right?
Thanks for all the help btw......

 

[griz400]

well, it wouldnt run without fuel, but it was lean for sure, (not enough fuel), like could be fuel filter, selector valve, but id be leaning on the mag carb, possibly internal sludge or clogged filter, but, sounds like to me, you will be doing it right, you seem like you will cover all the maintenance items, thats what people fail to do, some people eat a motor from just clogged filters, leaning out motor, and bam ... lean seizure ...... keep us posted on your progress ....

 

[griz400]

one more thing i thought of today while i was out on the water today, all that metal from cylinders, about half went out the exhaust, the other half as you know, is laying in your bottom end .... to do all this correctly, split the cases, bearings maybe, seals for sure -- with a look see and clean up of the bottom halves ....