First Top End rebuild Questions

harprhet · Dec 20, 2016

My sled is a 2004 Polaris Edge 800. My compression was low so I was planning on doing a top end rebuild. It was last winter when I tested the compression so I don't remember the exact numbers, but I guess my first question is if that is what I should be doing. From the research I did on YouTube the rebuild doesn't look to difficult. But was wondering if people ever hone or rebore the cylinder walls on the rebuild? I haven't heard anyone mention this so I am assuming not. Also I was just looking at rebuild kit on ebay as they are the cheapest, are these reliable, or should I just go to the dealer?

Mark's RMK · Dec 20, 2016

Rebuild 800 Liberty

If you are going to open up your engine you should replace both crankcase seals. Mic your pistons but depending on your mileage I would replace them.

For the rings to seat you will need to knock the glaze off the cylinder walls.

There should be a machine shop near you that can hone the nikacil cylinders and inspect them.

While I had the crankcase split for the seals I would have a good machine shop check out the crank as well.

Buy a good gasket kit but consider using Polaris OEM crank seals.

peaceofwork · Dec 20, 2016

Low compression ? Did you test with the throttle held open, it could be the result of bad or damaged reeds, keep in mind their is compression release holes in the cylinders on some models.

harprhet · Dec 20, 2016

So I didn't hold down the throttle when I did the compression test. What started this hole mess was my sled only firing on one cylinder when I was at low RPMs. I cleaned the carbs, checked the reeds, sparkplugs, and a bunch of other stuff at the time and everything looked good. So I haven't touched the thing since probably last march, so I don't remember exactly but I may have not even had the carb or reeds on when I did the compression test as I had it all torn apart. If so would this give me a bad reading. Maybe I need to redo the compression test. I have the sled stored at the in-laws, but will be there over this weekend and plan to work on it.

peaceofwork · Dec 20, 2016

if the reeds are not in while doing a comp test... put them it helps a lot as presurized air wont be escaping.
running on one cylinder makes me think you should fire it up a moment then shut it down and swap ignition wires to oposite spark plugs ,then if your non firing side fires it, great you then know the problem is one dead side on the coil or a bad wire or boot, if it dont fire it swap the spark plug over as well- if it then runs it means dead sparkplug.
keep in mind a plug might spark when out of the machine but not when installed and under presure.
its still a good idea to do your compresion test as good compresion is nesasary for combustion,

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First Top End rebuild Questions

harprhet

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Mark's RMK

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peaceofwork

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harprhet

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peaceofwork

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