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Discussion Starter #1
I bought new power valve cables for my 02 zr800 cce efi and I also decided to clean the valves while I was in there. The first did the pto side and discovered the valve made love with my piston. Very light mark on the left side looking from the front. The rings still float and marks are very slight. So i made my shims and reinstalled the whole unit. The pull start side was a different story. The valve never made contact on this side but the skirt of the piston looks very scored. The skirt on the pto side didn't have this. Should i just run the sled like this or rebuild the motor? The motor has 3600 miles on it and has never gave me a problem. It runs strong and always starts. Sometimes last winter it did feel a little groggy after 50 + miles of hard riding. It Felt sluggish but it could have been the tempature. How much longer can I expect out of this motor? I figured i would ask the experts on here. I can take a pic if anyone wants to see.

Thanks
matt
 

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Scoring on he exhaust side of the piston is never a good thing whereas light scoring intake side means snow ingestion. The best thing would be to ivestigate further and yes post a few photos so we can have a look.
 

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yup sounds like that side got a bit too hot....

a rule of *thumb* (hehe) is to run your finger nail across the grooves. If it catches your nail then it's maybe time for a rebuild. I don't know about you but I hate walking in the deep snow. I'm not saying it won't last another season but why take the chance....you have time yet to get her nice and new again. :)
 

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I would say your at the perfect time for a top end rebuild. You have 3600 mile on it and just because you have never had any problems from it doesnt mean you wont soon and now that you know you have some issues there, better now than in the middle of January. As for the power valves,,, arent you cleaning them every year?? Mine have always come out clean until this year on the f6,,,, for some reason, they were pretty bad (messy),,, but I still pull them and clean them every year.
 

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Discussion Starter #5
This is going to be the second winter I have owned it. So i have never cleaned them on the 800 before. I have to do them every year on my 600 and those are a pain. Will I have to replate my cylinders when I rebuild? Can I have them rehoned. Where is the best place to buy new pistons? Wiseco? I would like to know why it scored itself. You said to much heat? Is there anything that needs to be fixed?
thanks
matt
 

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as long as you have no flakes in your nikasil, no you dont have to replate them, only have them honed. I usually hone my own but you can contact Millenium Technologies and they will hone them for 25 or 30$. Take a good look between your ports for flakes or cracks. This is where they will usually be. Take your fingernail and run it across the cylinder,,, if it catches, you may be renicking also.
As for pistons, I dont care for wisecos, but there are many on here that love them,,, guess its what you yourself like. I have always ran nothing but stock in mine but this year I switched over to try spi pistons. I got them through JRGraham and I got 2 pistons with rings, wrist pins, and circlips for the price of 1 stock piston. I have heard nothing but good from them and I guess I will find out soon enough.
As for heat, your gonna build up heat in there, you need to make sure your getting enough lubrication. Do you know what ratio you were at last year with your oil?? Mine was way too low, sled didnt burn much oil at all. I also injested some snow through mine so a mix of snow, low oil, and a cracked y pipe, I did a number to mine. I am surprised the thing even ran at the end of the year.
Get some pics of what you have and get them posted and we can help you anyway we can.
 

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Sometimes you'll see some silver in you cylinder as well. That is some of the piston wearing on your cylinder wall. Use some muriatic acid and it will clean it up nicely. Be careful with the acid though. Don't get any into your intake or exhaust ports. It will eat any aluminum in there.

I have the same issues going on with my sled. I had to rebuild twice last year. First time was a new cylinder, second was just preventative because of low pressure.
 

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brotherd,,, nice to see you back around,, havent seen you in a while!!!
 

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Been way too busy!!!!!! Finished off the basement- doubled sq. ft in the house. Now the wife is happy!!!!! Let's ride!!
 
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