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Discussion Starter #1
It has been discovered that the 800's are starting to have some more problems. One of our forum mebers (I will let him tell you who he is if he wishes) came across problems on his 02 800. After checking compression he found that one side is way down. He pulled it apart and found that the facing on the rings was flaking off (serious problem). It has me scared!!! I will be pulling mine down to inspect this week. After talking to a few different people, it was found to be a problem more serious than this isolated case. The 800's run way lean between 6800 and 7200 rpm's which causes alot of heat to build up and the quality of the series III ring sets will not handle this heat. Those rpm's just happen to be cruising rpm's, and if you do alot of long trips at this rpm range, you just may have the same problem. Better safe than sorry!! Hope this helps keep someone of the side of the trail with the hood up and a wasted weekend.

Brian
 

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yes, that would suck. although it kind of sounds like me last year. :devil:
 

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kelsey at rk tek has a kit with new pistons that solve the problem it has a dual ring design and different type of piston dome that disapates heat better,the pistons retail for 275 us$ ,ive been debating getting the upgrade,ill know in another 3 weeks if i will try this out
 

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Same deal for 01's? Had the piston update done on mine and I have jetted down(Elevation) Use Boyessen sp? reeds as well for response. We rarely see WOT for long periods of time because of the terrain. Am I asking for burndown? My cruising rpms are lower as well, clutch setup.
 

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MXZWFO thanxs for the heads up. What kind of oil was your buddy using?
Did he rejet? Which side was the compression down on? I am going to check the compression on the 02 mxz800 gade today.

Sounds like the way to avoid burndown is to stay in the powder at WOT
;)
 

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From what I understand the moly coating will start coming off the rings. This should not lead to melt down, but compression will be lost. The rings can't handle the heat.
 

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I just checked both cylinders on the 02 gade 800 and they both read 140 bang on. I take it that this is just about right. The sled has over 5000kliks on her/Amsoil.
 

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Permafrost, I have always found that if I'am going to heat up it's WOT in the powder not the lake. What I'm saying is, if I was jetted safe for WOT on the lake with no drag and jumped out in the powder with lots of drag I would burn down in a heartbeat! :hallo2:
 

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I think I'm the one mxzwfo was refering to. I decided to check compression on my sled as part of the pre-season prep and found that I was at 135 and 140 as opposed to 150 and 152 last year. I have 2000 miles on the sled. I use standard Doo oil. Always have. No I did not jet down. I was still running the 520N jets and RPM's were at about 7800. All where it should be. Decided to pull it down and found to my dismay that the rings were trashed. Cylinder walls and pistons look pretty good yet. Bearings seem to be fine. WOT is NOT the problem here. It is all in the midrange where we all run. If you are cruising the backroads at 50 MPH for extended periods, you are definitely suspect. I would chceck it out NOW. Better than setting on the trail somewhere with no compression. Still looking at alternatives now. Good luck to all you 800 owners. I still :inlove: my sled in spite of the probs. We'll get it all worked out. Just be sure to check it out folks.
 

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Again thanks for the info MXZWFO. I personally have tried about every setup on gods green earth and properly jetted, good gas, and amsoil or equivilant in the bottle, my 01 mxz 800 has lived through it all. Maybe i have just been lucky but i think your buddy might have something else wrong in his setup. You are correct about the midrange hot spot though. If you give me all the details maybe i can steer your buddy in the right direction so he can stay off the side of the trails this year. There are alot of us 800 owners on this forum, i am sure someone can help him out. happy sleddin. ???
 

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Whats up idooski. It doesnt sound like there is a problem with your setup that would have caused your problem. Although i will pm you and tell you how to fix your midrange problem that was obviously the culprit. :D
 

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Moly flaking off the rings is a concern but you shouldn't feel threatened, it won't cause you to burn down. The ones I've seen have been small pitted spots on the ring face. Consider many engines run iron or stainless faced rings with no moly facing. So even if you were to lose ALL the moly you'd still have a conventional ring so to speak. The moly rings are a lot easier on the bores and offer lower friction. They don't do a good job of transferring heat from the dome to the cyl wall though. All series 3 motor suffer this, not just the 800's. Though the 800's may generate more heat for whatever reason? I do not believe the flaking will show on a compression test if the rings still have good sharp top and bottom edges and are within spec. My .02
 

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One ring still had the flakes hanging off it. Seems to me that with just chunks of the moly hanging there, that the compression would suffer. I wouldn't downplay the problem too much. I'm just trying to let people know what's up. I treat my machines right and they are dialed in. To me the rings losing the moly is a problem. Probably not a stranding problem, like you say, but it could cause some serious stress when the thing isn't running right and you are miles from camp. Only letting you know what I've found.
 

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They've discussed this issue in tons of mags over the last 6 months so it's deffinetly not isolated. Can't remember the Doo stance on the issue though.
Caleb
 

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I pulled the comp tester out on mine tonight and the old girl pulled 153 and 150, same as 1 year ago. Been 2300 miles since the recall. I will eventually teardown the eng and see. I know the 2002 ign has more advance in the midrange than the 01 though. Maybe the pipe?

I have run the Dport on mine, a set of Aaen twins (@ 8200 RPM) and back to stock.

My head has been re-shaped also, but it looks as tight as is did the say she went togethr. I have looked at what ring I can thru the ports and they seem fine, but we wil see.

Been run on Klotz since she came home
 

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Discussion Starter #20
Pulled my sled down today and found the rings to be pitted around the transfer ports on the exhaust side... :cussing: .My sled only has a little over 200 miles on it!!!!!! The exhaust side of the pistons was pitted also around the ring lands....I guess I will try to shoehorn my BB Chevy into the bellypan :D .
 
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