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Ok-1996 zrt 800 just bought-previous owner had a small fire and redid the fuel lines backwards which is why it would only run on two cyl briefly. fixed that problem. Previous owner also said he had not ruin it for 2 years. check everything over and I go to the mountains. did the carbs as well top to bottom. go out for a couple hours, check plugs(choco milk coulour). trailer it go to a bigger mountain. offload starrt5 let it idle for 3 minutes (0 Cel outside) Jump on and go half power or so-3km later it runs bad on 2 cyl then dies. Check hood, check plugs all 3 good. Start it and no prob. Go another 1 km and it dies. open hood and Coolant leaking at base of jug next to clutch. I leave it there and ride a diff sled the day. Tow it down later and pullo it into shop to replace base gasket.(what makes a base gasket go?-dries up?backfire?) Anyways - get the jug off and the rins are a bit melted into the piston and the jug is scored very slightly. No spare piston with me so I pull the cover off the 86 formula plus with the conveyor belt to get me through the rest of the weekend. my back still hurts. Anyways--there was slight backfiring here and there when we first started it up, but other than that once we drove it for 2-3 hours in the morning it was fine. The piston looks scored on all sides but it is not burnt on top. I am about to order the piston kit to fix the problem but I want to make sure there are no other problems that would cause this again. Also when i got the piston out there is a small tab of metal inside the crankcase at the back on the carb side right in front of the reed valve, it has a little slit in it. This is broken off on the bad cylinder-only about a 1/4" though. (hopefully this wont matter too much as long as I get the metaql out of the case...right?) I am all ears Oh wise Ones....Pleaes help.
 

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Oh and I forgot this piece of info too. During the day I had to flip the half choke on every once in a while or it was weak on fuel. not all the time just every once in a while. And when i bought it I drained the fuel from tank (because prev own said it had been sitting) and it wa mixed in it. I added a bit of mix with fresh gas topped up inj pump in the morning of the riding day and monitored to see that it was going down (it was). more facts for you brilliant wise ones.

PS-I really want to go sledding in 2 weeks because we have a 15' base right now and there is way more to come. please?
 

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not sure what answer your after,,, you will have to replace your piston, you already know that. Do you need to send the cylinder off to have it renicked?? If you have chips in the nikasil near your ports, send it off or you will end up catching a ring on your new piston and trash it again pretty quick.
As for why it happened,,, if you had no oil or residue on the top of the piston, thats water. You could have gotten water in there and that took the piston out. A picture of the piston would tell us more. If you are in the mountains and in that much powder, snow getting injested into your system is a very good chance,,, start looking for where the snow could have come in.
 

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I ordered the wiseco piston kit yesterday. I dont want to #### around if the pistons are factory or not and I replace one(different weights). Also picked up a new used jug for the pto side little scored, and again dont want failure. Is there much worth in pressuring the case when everything is back together to ensure no leaks? Basically if I plug the spark plug holes, intake and exhaust i should be able to do this right? What is the best way to plug intake and exhaust? I think the piston had some water or coolant and that was the culprit. Where from? dont know. I need a reliable (but powerful and fun) sled for where we go, and I hate to say it but if I have to do any more little things like this on this one its probably going to go soon.... Last question-the rear suspension link that the limiting strap hooks on to. The small bar on the bottom side of the strap has broken. Is the limiting strap supposed to be so tight that it holds the suspension down or is somethig out of place. The bracket that it attaches to is slanted forward right now and I would like verification that it is supposed to be slanted back and also how tight the limiting strap is supposed to be on it. Thank you in advance for the answers.
 

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suspension is fixed. It slants slightly backwards for any one else with trouble. The limiti8ng strap stops it from going forward. Could a leak in the crank case have cause d the piston? and the having to choke while going problem? If swo how difficult is it to do the crank seal while the top end is off?
 

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I think the piston had some water or coolant and that was the culprit.[/b]
Water OR coolant? I know you said your plugs were choco milk color, but was there any "flakey residue" on the ends of any of your plugs? If so, you're eating coolant.
 
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