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The Cats Took A Beating This Weekend

2248 Views 14 Replies 8 Participants Last post by  bombardier01902
Six of my buddies and I went to Baraga-near houghton Mi this past weekend for a 4 day ride trip. Four of us were on cats, 3 were on doo's. Both my buddy and I have ZL600's. We both blew the same cylinder within a hundred miles of each other. Mine has more miles than his, but they gave up less than 24 hours apart! Then another buddy (westernbronco) lost his CDI. Needless to say the doo guys gave us a ton of flack!!

I guess the season is over now for sure. The conditions were the best I have ever ridden, I am still bummed I didnt get to ride the rest of the weekend. We saw more groomers than sleds, 2 to 1!!!!
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me to last week the left side this week the right
Bummer. Did you find out what happened?
Not sure yet. I am hoping to at least pull the head off mine tonight. Pretty sure the piston skirt came apart and a peice got stuck between the piston and head. I really don't have a place to work on it anymore. I used to have a nice heated barn, but I just moved. I barely have a garage at my new house. Good think I have heat in the trailer. Looks like thats where I'm tearing it apart.
Let ,me guess

Both had the mag side go :sly:

Pretty sure mine was cold related. We sat for about 20 minutes. When I started mine, my buddy was right behind me. I couldn't resist, since we were in the deep snow. I opened her up and powdered him. I think it was about 200 yds down the trail when she gave up. My clutch side plug looked good. My mag side plug was crushed. I'm chomping at the bit to see what happened. I guess at this point it doesn't really matter. All of my funds are going towards the new barn. The season is over anyway. I just at least want to know whats wrong.

His same cylinder gave up. His was oil related (we think). His clutch side plug was white, and mag side crushed. His pipe had about 8" of white ash on the outside too. We are thinking his pump failed.
The most common failure for Cat's in those years is the ring turning and hooking an exhaust port.
Are the ZL's, EFI's??

Sounds to me like you got bad gas.
I work at a snowmobile repair shop, I can't tell you how many efi's we fix after they come back from the western UP from a bad piston.
There is a ethanol wire that you unplug right on the ecu, it gives the engine 6% more fuel and will keep it from burning down if you get watery fuel, when ever you are in the UP, it needs to be unpluged, The gas up there sucks.
The carb sleds you were with are not jetted as lean as the efi's and will tolerate some bad fuel without issue's.
The efi's run right on the edge of a burndown anyway, and it will be a lot more forgiving with the ethanol wire unpluged.
Hey super, sorry about your luck. If those were OEM pistons in your sled I would lean toward what newf said about the piston pin. A couple guys I have ridden with have had that prob on their 600's around 3,500 miles or so.
If your buddies 600 had a lot of ash on the plug or in the exhaust I would take a good look at the intake side of the motor. This is many times the result of high cylinder temps rather than lack of oil. I have seen this mostly on sleds that have intake leaks like real bad carb boots, improperly installed reed cages, even one where the carb slide cap came unscrewed.

What ever you do, don't put OEMs back in. I can't say enough great things about Wiseco, they are almost bullet proof in my opinion, but I have heard people having good luck with SPI's too.

I feel your pain, I lost my second stator on my ZR6 this week in Newberry. It just rolled 11,000 miles (7,000 of those with Wiseco's) and I can't justify putting a $550.00 dollar part into a sled thats worth $700.00 at best now. Time to replace it.
We also lost 2 Doos, one with a bad trailing arm mount that pulled out of the bulkhead and the other had a spark plug left loose and burned down a cylinder.
We still managed to get almost 700 miles in in 3 days (good thing I brought a couple back up sleds) in some of the most perfect conditions I have ever had.

Good luck man, let us know what you find.
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OEM Pistons. I finally tore it down this weekend. My piston skirt issue seems to not be true. The bottom half of the piston looked fine. It really doesn't seem to be heat related. It does not look like it got hot at all. The PTO side looks great. I think what happened is the top ring broke. Obviously from there, it did the remainder of the damage. The bad thing is that the cylinder is toast. I'm pretty sure it is Nik plated (correct me if I'm wrong) so I have to buy a new (re-man) cylinder, or have it resleaved. My buddy is a dealer for SPI pistons, so I get a killer deal on them. Looks like that's what I'm going to try. I have always had great luck with weisco's also, but for the money and what people are saying, I'm going to try SPI this time.

I think we are going to put a new top end in the other ZL this summer also, just to be safe. It is now over 3000 miles as well.

Oh. Snow800 Yes both sleds are EFI. That is a possible cause for his, but he hasn't torn his down yet, so we don't know much other than the plugs were white, and the pipe got hot.

Either way, looks like I have a nice new handle for my tap!!


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Pull the damaged rings out of the piston and look for the retainer pin. I'll bet it's not there. Actually, it'll be there, but it will be pushed further in to the piston then it should be, meaning the ring was free to turn. Only a matter of time before the end hooks a port and boom.

Do both sides cause the other one is going to go in the next 1000 miles.
I was going to do the other side for sure. I always do both when I tear anything apart this far. The way all the gaskets come. All the other side is going to cost additional is the piston kit for one side. It would be silly not to.
Millinium Technologies (sorry, probably butchered their name) has always done a great job re-plating cylinders for me and they are reasonable.
And yes, they are Nik plated.
I think thats who my buddy uses. They do an exchange from what he said. They send you a good one and a box for the old one. You send in the bad one. Supposed to cost around $150. Seems ok to me.

Just have to explain to the wife now, why my little trip got so expensive.

Parts list.

2 piston sets
top half gasket kit
new/replated cylinder
whould got a ski-doo the rotax engines are the best you can get
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