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Discussion Starter #1
hi i was wondering at what point is it time to rebuild, i have a 97 polaris 700 mod sled with 5500 miles, the compression is about 100psi, i was told that the lowest possible compression is 90psi which has got me concerned, also should i buy new cylinders and pistons or just buy pistons that are bigger than factory to compensate for the loss of compression.
 

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Usually, doing just the pistons helps to regain lost compression. If you were to go to larger pistons, you would have to have your cylinders bored. They are nikasil lined and that stuff is hard. It takes special tools to remove the nikasil and then the boring is done, then the cylinders are re-lined with nikasil (I'm assuming you have a 700 twin). With the miles you have and the loss of compression, I would install new pistons/rings and have the cylinders checked for possible damage. The early casting had issues with port bridges cracking. The early cylinder part number ends in 220. If yours end in 824, they are a newer casting with less issues with cracking, but make a little less power. 220 cylinders in good condition are pretty sought after in some circles. If yours are in good shape, I wouldn't replace them. If yours do have cracks, they can be repaired for half the cost of a new cylinder. (This all assumes you are talking about the 97 Polaris twin cylinder engine.)
 

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Discussion Starter #4
ok, these are 700 twins, would u go with the stock sized piston or have a larger one, i dont want to bore it out unless i could do it for cheap, i thought that loss of compresion was from the cylinder wearing out along with the piston, so i could get new piston and rings and be good to go you think?
 

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Most likely stock size, even if the cyl is scratched, they can be fixed. Unless you want to do a big bore setup. I've done several big bores and there isn't anything to it other than working the head to the correct diam. I us US Chrome in Wi. To replate is like $165-175?
 

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what is wrong with the engine now? did you check comp. the proper way with a gauge that you are sure is reading true? If it aint broke dont fix it, while you have a lot of snow to ride on. theres a lot of time in the off season+shops will do it for less money sometimes. my 700 edge has 9000 miles on it never been torn down+ wont be as long as it runs great." RIDE EM TELL THEY ROACH" they can sleep when there dead,thats what I say.
 

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what is wrong with the engine now? did you check comp. the proper way with a gauge that you are sure is reading true? If it aint broke dont fix it, while you have a lot of snow to ride on. theres a lot of time in the off season+shops will do it for less money sometimes. my 700 edge has 9000 miles on it never been torn down+ wont be as long as it runs great." RIDE EM TELL THEY ROACH" they can sleep when there dead,thats what I say.
have you ever blown a 40$ set of rings and it cost you a new cyclinder pistons and heads and ruin perfect ridding time?

change it b4 it blows its cheaper in the long run, my banshee i rebuild every winter and my sleds every second year at least the rings and check it over never have anydown time that way
 

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Discussion Starter #16
k i well replace them when i get some extra dough, is there any way to find out if it has naskial without taking it apart?
 

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twins rule!
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What makes you think it will blow? I have been running 2 strokes for over 40 years+it is rare that one has failed me just because of high hours on the engine. I have chain saws over 30 years old that run fine never been rebuilt, a 91 350 2 stroke 4+4 polaris never been touched, a 81 yamaha dirt bike one set of rings in 30 years 3 polaris edges with a total of over 16000 miles never been rebuilt I could go on+on. if someone likes doing rebuilds "many do" thats great, been there done that. but if it aint broke or about to brake I dont fix it just because I can. I take that money+buy more toys or take more trips. what im saying is if it runs good now keep it on the snow+put it in the garage after season. maybe im wrong but I have many good running sleds for the same price that a lot of people have in one. It works for me but I did learn it the HARD way.



























































'many do thats great
 

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Discussion Starter #18
one other question, which type of piston wiseco high performance, stock, or spi. also do u guys know any place online where i could get them for cheap?
 

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^^^^ 100 psi mite as well be broken
 

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If it's not broke..... Do a little bit of work and keep it that way! The best thing you will ever do for your pocket book is preventative work. I put new pistons in every 2000 miles,, and if you do it yourself (it's pretty easy) it doesn't cost much.
 
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