whats wrong with my 02 rmk 800

[travysho22]

Buddy recently bought an rmk 800. He got it home and we cleaned the carbs, power valves and did general maintenance on it. We looked through the valves holes and realized the pistons looked really scratched up. Tore the engine apart.

1. For a sled that ran fine and had 150lbs compression what would make the pistons look like that?

2. We found a hole on the case near where the water pump is located. The hole is all the way through. What should I do about that.

 

[cascadesnowjunky]

With damage like that the whole engine is pretty much scrap metal. I know this is not what your wanting to hear but the cases, pistons, crank and at least one jug is toast. I would be looking for a parted out 800 with a good engine. To buy all the parts new and assemble a new engine you will probably be into it for more than the sled is worth, unless it has some sentimental value maybe even just part it out.

 

[mike_s]

Looks like the piston pictured has been seized at one time or another. If both look the same, you're looking at a piston set and have the cylinders re-niked at a minimum. As far as the hole in the recoil housing, IIRC it shouldnt be there, but that part of the housing doesnt contain anything liquid, so it could be run like that. Check the oil pump, water pump and drive belt inside that housing. Could be that whatever made that hole broke the belt and caused the oil and water pumps to cease opperation and create the seizure.

 

[IA ditch banger]

Mike is right about the pistons im not too sure on the hole tho. I have a 02 RMK 800 and i took it to the shop to get carbs cleaned because i have been to busy and i heard them talking about some sort of hole and somthing to do with high altitude compensater. I really dont know what that is im just sharing that to try to give you an idea on what it might be. Sorry

 

[mike_s]

On a side note, unless the engine has some kind of high performance head, or the head has been milled, the compression should be closer to 120-130 pounds. 150 is getting into 91 minimum octane range, IMO. Could have been a contributing factor to the seizure as well.

 

[travysho22]

i do know that the guy before ran the sled on premium only. 91octane. he said that he replaced the water pump belt to. so maybe he ended up running it to hot by the time he realized that the belt had broke?

were still puzzled on what created that hole in the case. like you said there is no liquid in that part, but you also dont want other things getting up inside the engine.

 

[mike_s]

i do know that the guy before ran the sled on premium only. 91octane. he said that he replaced the water pump belt to. so maybe he ended up running it to hot by the time he realized that the belt had broke?

were still puzzled on what created that hole in the case. like you said there is no liquid in that part, but you also dont want other things getting up inside the engine.

Thing is, if that belt broke, the oil pump stopped injecting oil at that point. Doesnt take long without oil to make pistons look like that.

Far as the hole, who knows what made it. But if you cannot afford or dont want to buy a new housing, one could cover the hole with a piece of foil tape to keep small debris out. Might not stop large stuff, but you shouldnt have big things bouncing around under your hood anyways. LOL!

 

[bern one]

What ever caused the hole in the case came from inside of the crank case, pieces of piston or whatever... the case is done, could be welded but the tape method I wouldnt recomend!

 

[whoisthatguy]

From the looks of the scrape pattern to the left of the hole, it looks likes the engine was previously in another sled that T-boned an immoveable object.

 

[mtncat1]

pull the cases apart inspect the bearings,if they are ok. put it back together, have the cylinders inspected, sometimes you can get away with honing them and replacing the pistons,you can either replace the housing with a used part or just block the hole. it all depends on what you want to spend. I,ve done hone and pistons with slight cylinder damage and they ran fine.

 

[X2Freeride]

What ever caused the hole in the case came from inside of the crank case, pieces of piston or whatever... the case is done, could be welded but the tape method I wouldnt recomend!

Its not the crank case... Its the recoil housing... What probably happened is the recoil spool broke and put the piece jammed up to the top of the hosing and then broke the piece out of the case. Either that or this sled took a frontal impact and something pushed into the engine and caused the hole. The engine is EXTREMELY dirty and doesnt look to have been very well taken care of.

 

[likinit2]

Just buy some new pistons and rings. Check and hone or renic as needed for the cylinders. Put it back together. Make sure your fuel pump is up to snuff. Check jetting. May have been a cold sieze etc. Air box gutted etc. ???????

As for the hole, it obviously isn't hurting anything. looks like somebody took the time to polish off the edges with a dremel. Does it belong there? NO but it really isn't a big deal. the metal tape idea will work if you really feel you don't want it open like that.

SPI pistons will work fine. Be sure to use the polaris metal base gaskets.
Hopefully you can salvage your cylinders other wise that will set you back some money and it doesn't look like the sled/engine may be worth getting too deep in the pockets. If the rod ends don't look like they had high heat run it!

 

[TerribleTer]

Just my two cents, i have seen guys jam their shovels or other tools into these places, this could have worn the hole, I did that with a set of pipes and wore a hole into them,

 

[snowx99]

Looks to be heat seized. Without seeing the top of the piston, cannot confirm detonation or not. Jetting is borderline from what I see, either for temps or elevation you are riding.

For my own piece of mind, I'd pull the engine out and tear it completely down. That way you know the condition of all important parts. Build it fresh with quality parts and attention to detail. Should provide many miles of fun after that.