cat 800 efi SEIZED!!!

Pobuda · Dec 2, 2007

!! HELP !! MC 800 efi SEIZED!!!

i just purchased an 02 mountain cat efi 800 a few months ago it has been out west a few times but i was riding today in minnesota and after about 21 miles today on a trail the sled burned up i pulled the engine apart and what i found was that the plugs were melted on the electrode and the pistons were somewhat melted on the tops and the edges a bit!! just enough to seize it up i am not sure what could have caused this it was sputtering a little bit after about 20 minutes of riding so i **** it down and let it sit for about 10 minutes then fired it back up and it seemed normal so i proceeded to ride then about 15 minutes later this happend i have never owned an arctic cat only polaris and also never owned an efi just carbs! so i am at a complete and utter loss here any thing will help so PLEASE REPLY im supposed to leave on the 15th to go out west and ride the mountains as that is why i bought this sled!!!

thank you,
scott

Fresh Tracks · Dec 2, 2007

I would go back to the person you bought it from and ask if he had any mods on this sled or does it have any aftermarket stuff on it now, as this sounds pretty suspicious to me I have an 03 800 EFI (900 now) and they are notorious for burning rich, how many miles are on it, I have never had a problem with my motor and I have done a wack of stuff to mine, everything from a speedwerx single pipe to Jaws twin pipes with shaved heads and never had any issues, I only installed the boondocker box when I got the 900 jugs, as I am still running the jaws twin pipes, mysetup is still running good about 3700 miles on mine,

One thing that did happen to me and this was my own fault was the oil screw backed off and I wasn't injecting hardly any oil, luckily I was adding a bit of oil to my gas tank at the time and I caught it before anything happened.

does it have an aftermarket air box or anything on it also. give us some history on the sled if you can.

FT

diggerdown · Dec 3, 2007

Like fresh tracks said, they usually run rich. Without know anything about the sled it is hard to make an acurate assement. Has it had head work? With the plugs gone like that it sounds like detonation. Maybe too much compression for the fuel and altitude. Is there a fuel reducer on it? Timing key? He may have had it tweeked for high elevation. Contact the former owner and fine out what has been done to it. Chances are there is some type of modding for elevation that caused this.

Smashcat900 · Dec 3, 2007

I'm riding an 04' 900 EFI and I burnt it up last year. It had something to do with the check valves coming off the oilers. According to the dealer, at high RPM's, they quite working how there supposed to and didn't let oil into the system and smoked the engine. It died on me and then about 15-20 min later started back up and ran a little longer and killed over again. There wasn't much for damage on top of the pistons rather more to the walls of the jugs. I'm running a "Thing " can, gutted air box, Boysen reeds and clutch work. With this set up my plugs are running more towards the edge of to rich rather than to lean. Like diggerdown said, it sounds to me like some kind of modding for elevation.

Pobuda · Dec 3, 2007

the only thingi have done to the sled is a can its a sno stuff rumble pack and there is about 1100 miles on it thats all i really know about it and the guy i bought it from isnts answering! go figure!!!! i thought the computers were supposed to set themselves for the elevation junk!?

Pobuda · Dec 3, 2007

also can i have those jugs resurfaced i was told i cant by a friend but i believe that you can what do you think?

CATSLEDMAN1 · Dec 3, 2007

A little hot?

too much heat, that we can establish, both cyl got it?, so likely not a bad seal, that usually takes one side, not both, and ditto for the fuel injection, black box screw up? maybe............but haven't heard of that too much on the 800/900s.

So too much heat, not enough cooling?, 2" track no scratchers on cold even some snowdust trails will create 180 degree water temps right now on my two pals 800's, one carb one efi. And if you ignore it real hot water will lead to detonation at mid range throttle and 25 miles of that will burn up an old 800 with loose pistons, if the backs of the pistons have fatugue cracks? too hot too long seen that. Fat efi and wide wash doesn't mean its fat everywhere. 1/3 throttle trial riding is lean on most cats, and no snow with that 2" track?

Pobuda · Dec 3, 2007

i brought the cylinders in today and they say it cold siezed because i did not let it warm up enough before it got rode. and also that the bad gas would cause it to lean out and heat up! who knows when the gas is from i did not drain it this year and who knows when the guy i bought it from rode it last so i am gonna have all the parts on friday and then i will get it back together and hopefully it will treat me a lot better this time around! by the way what are snow scratchers?

JMCX · Dec 3, 2007

If the plug electrodes and piston tops were melted it wasn't a cold sieze. You are most likely a victim of old stale gas.

Pobuda · Dec 4, 2007

well the guys at the shop said there was also evidence in the cylinder of a cold sieze too but yeah thats what they said also cause the can was white in the internal side so they said it was old stale gas that leaned it out hardcore so i guess it was just a costly lesson!!!

arcticridr · Dec 4, 2007

Even if it wasn't a cold seize you better learn to let the rear exchanger get warm before you ride it like you stole it or a cold seize you will have!!!!! I let my KK idle for 10 to 15 minutes depending on air temp or until rear exchanger gets warm before i flog it!!!!!! Buddy or 2 of mine have both learned that the hard way 2pistons 2 jugs on one and 1 and 1 on the other ! Sounds like crappy fuel did you in ,most are so fat lean seize is pretty impossible!

Pobuda · Dec 4, 2007

yeah i will let it warm up from now on thats for sure would you recomend putting in a engine temp guage because my light never came on!!!!

amery3 · Dec 4, 2007

Since it's probably the stock, forged pistons in there, a cold siesure after running that long is almost impossible. It probably can be done, but not likely. The forged pistons are the ones that'll give you trouble. That said, it is good practice to let it warm up, but 5-10 min is plenty for most conditions.

I would guess that it's a case of poor snow conditions, and not enough snow being tossed up onto the heat exchangers. Those 2" tracks set you up pretty high and not much snow gets tossed up on the hard pack. To make matters worse, I believe that these engines run warmest from 1/3-1/2 throttle, right where most people ride trails. Correct me if I'm wrong, someone. To remedy this, vary the throttle while you ride it a lil bit.

Most of the 800 and 900 cat engines are rock solid-it's probably the best thing about the whole sled. You may also want to clean the injectors.

I'm a carb man, but could it be a partially plugged injector? I know that a partially plugged main jet is bad news.

SaberKitty · Dec 4, 2007

Wait until there's more snow to trail ride a mountain sled in MN. The 5-10" of fluff on the ground now isn't enough.

Definitely need scratchers to keep the engine (and track!) cool for trails.

Traditional Style Ice Scratchers

New Style Ice Scratchers

Pobuda · Dec 4, 2007

ill keep that in mind like i said i appreciate all this help!

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