melted center piston

just for checking sake, take a bright mag light or suitable flashlight and shine it in your tank, see any water? or jelly looking in the bottom? will look like clear jelly looking, be at the bottom of the tank, if the light is nice and brightits usally easy to see thru the gas, depends if its real full or not though, see whats in there......
 
mrviper700 said:
just for checking sake, take a bright mag light or suitable flashlight and shine it in your tank, see any water? or jelly looking in the bottom? will look like clear jelly looking, be at the bottom of the tank, if the light is nice and brightits usally easy to see thru the gas, depends if its real full or not though, see whats in there......
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I can't thanks you enough for all the help and advice ur giving me. Its awesome
Tank is right full can see to the bottom
This is what I can see looking into the tank
7C620154-2884-4AA1-80B6-E8F1C9A654C1-5109-000008BA5ED56240_zps1677883b.jpg


This is some gas I siphoned into a cup
4DCA2F61-E704-4A20-BB24-AB61981B2958-5109-000008BA66F63DA4_zpsbf0b7abb.jpg
 
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gas looks good. Doesnt tell you what octane it is but at least no jelly in the bottom(water)

nothing in the steel nipple on the carb into the seat area on carb?

most times if you lose a cylinder while wide open its a fuel obstruction of some sort, water in fuel, something like that. There was a guy in the vmax section found a chunk of plastic on top of his seat. I have seen stuff like that , like jelly looking goop on the screens so thats why i had you pull those, if nothin else you know they will be clean now.
 
I just got a viper engine shipped in today and he had the exact same cylinder go down and his pistons look like yours, he also said it was low on coolant when he took it apart. His went down tho at low speed while riding his wife around. I am going to look at his carbs as well.

he does not have a rear heat exchanger on his, just the factory cross tube, do you have a rear heat exchanger on yours by chance?, just asking out of curiosity.
 
mrviper700 said:
I just got a viper engine shipped in today and he had the exact same cylinder go down and his pistons look like yours, he also said it was low on coolant when he took it apart. His went down tho at low speed while riding his wife around. I am going to look at his carbs as well.

he does not have a rear heat exchanger on his, just the factory cross tube, do you have a rear heat exchanger on yours by chance?, just asking out of curiosity.[/QUOTE

Don't have a rear heat exchanger.
I was riding on trail with about 4 inches of snow....when it burned down I felt the heat exchanger on the running boards and they were cold to touch.
A few weeks ago I had the temp light come on in low snow conditions so I packed snow on the running boards and it was fine
While riding about half a mile before it burned down I noticed the rpm would only go to 8000 and slowly climb to 8400-8500. It usually shoots right up there
And sorry I forgot to mention in my last post I blew some carb cleaner through the nipple and then blew air through it. There was alittle bit of milkieness to in it other than that it was clean
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When gas is suspect I usually siphon a gallon out making sure the hose is all the way to the bottom of your tank, put it in a clear plastic jug like a cleaned out juice container and let it sit and see if water settles on the bottom.

So where did your coolant go? Did it puke out the overflow because it was hot or is it leaking somewhere? Could it be a bad head gasket? Just thinking out loud.

Seems like there have been A LOT of burned down vipers in the last few years.
 
mrviper700 said:
I just got a viper engine shipped in today and he had the exact same cylinder go down and his pistons look like yours, he also said it was low on coolant when he took it apart. His went down tho at low speed while riding his wife around. I am going to look at his carbs as well.

he does not have a rear heat exchanger on his, just the factory cross tube, do you have a rear heat exchanger on yours by chance?, just asking out of curiosity.
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Did you figure out what caused that one to go down?
 
O2viper700 said:
Did you figure out what caused that one to go down?
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cant find anything wrong with the engine, you can see it was definitely hot but the waterpump and so forth look good, no signs of leaking from the weep hole, impellar tight on shaft,etc.

I am supposed to be getting the carb rack and will go thru that to invetigate.

he might have merely overheated it and once hot it just belched all the coolant from the overflow, riding 2 people around and slow, with no snow going on the exchangers was just the mixture of bad things and it got hot.

not sure on yours going down at WOT is suspect, but your carbs look clean. I figured youd find the cuprit on the needle/set top.
 
I was doing some reading on melted pistons and I read it could be caused by improper engine compartment ventilation or something.
5-10min before it melted I went throught a fricken huge drift and when it was in my garage I noticed both air inductions were plugged shut with snow.
Is this a possibility or not really
 
I don't know about that.Look at all the mountain sleds in deep 5 foot powder that you can't even see their hoods..is there a restriction there..they keep going.If you had a lack of fresh air going to the carbs,I would think it would be running on the rich side...could be wrong here..others can chime in..
 
if you block the air it will choke the engine and will make them run ritch ...if u still got your foam on top of the air box im sure the trouble is not there...
 
That is correct, No air = no fire. Same concept as using a fire blanket to smother a fire. If it can't get oxygen it won't burn. Too much air on the other hand would lead to very hot conditions.
 
I found what caused it.
A washer or spacer from the needle bearing blew on the bottom of the rod and sent the peices into the top end. Now when I move the rod back and forth it feels gritty.
#$%&* :whine: :o|
 
modsrx said:
need to find a new crank ..............;-( and piston
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Or part it out and buy a new sled.. I dunno if it's worth it to rebuild it I might part it out or sell whole.. there's a guy who buys blown sleds and he said he would give me $1200.
 
its up to u ...1000$ your back on trail that for sure maybe less if u do your own work....where are u in Ottawa ???
 
I have a crank and cylinder and also should have a good used piston if you want to rebuild, $600 for all of it plus shipping
 
modsrx said:
its up to u ...1000$ your back on trail that for sure maybe less if u do your own work....where are u in Ottawa ???
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Ya.
And I do my own work.
Iit's gonna cost me 350 to do the top end, $400 plus to rebuild the crank,
it needs a new track and new shocks aswell
 
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