Snowmobile Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
41 Posts
Discussion Starter · #1 · (Edited)
Diagnosis on a Artic Cat 700 EFI engine. It failed, why? *Pics*

Last winter my sled started knocking, by the time I got it home, it was severely underpowered, loud and hard to restart when it stalled. Im not sure what it is yet, as I havent taken it apart to diagnose. My best guess was I fried the bottom end bearings or did the crank in, not sure. Theres two reasons that I can think of on why this might have happened. 1) its a fresh rebuild (done by the previous owner) so I was thinking it was his misdoing. 2) the oil injection might have failed. I dont know much about this engines, so ANY tips or helpful hints will be a great deal of help. What Im looking for is a spec sheet for retorqueing, some how to's on a tear down and rebuild and some helpful diagnosing/troubleshooting info. My goal is to have this diagnosed and ready to order all the parts I need by late this weekend. Thank you

Jeremy
 

·
Registered
Joined
·
282 Posts
sounds like it might be a good idea to purchase a service manual
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #3 ·
Yeah it would, but I love the fact that there are no artic cat dealers/service stores in this area. I really didnt want to order it off the net but I might have to. Ill look around this forum and see if there is anyone selling one.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #5 ·
sesnopro, are you speaking from experience? Are you saying this could be spark knock? This is a loud knock, hard to believe it would be bad timing. Ill try to start it up again and see if I can feel the knock or if its only audible. That would really make me one happy dude.
 

·
four gear pinned
Joined
·
1,991 Posts
thats one of the reasons that the engine would knock the other is bad gas.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #7 ·
Im talking about a rod knock. I think I fried a bearing on either the crank of the rod end. Little bit different than spark knock ;)
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #10 · (Edited)
Went to work on it tonight. I started it for the first time since last winter and it started right up. Ran rough at first but cleared up. I was happy as can be too because it wasnt knocking......till I brought the revs up to 4k. Thats when it started knocking and wouldnt stop till I shut it down. The cylinder closer to the clutch is def F'ed up. It only had 39psi when I checked for compression. The second cylinder wasnt as bad, with 85psi. This really sucks, I hope its only the top end thats damaged. And we are supposed to get a record setting 2-4 feet of snow this weekend.
 

·
Registered
Joined
·
40 Posts
Engine Trouble

Did you look into the sparkplug hole with a flashlight to see if there is a hole in the piston.When you burn down a piston the melted aluminum can end up in the bottom of the motor causing rod bearing problems.:confused:
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #14 · (Edited)
I only got the head off of one of the cylinders, but from it looks like, it ran lean. Its burnt bad. Head is also burnt almost as bas as the piston is. I have to have the jugs sent out and bored, they are scored pretty bad. Ill post picstures soon.

Heres the picture of my piston, the head looks just like it http://community.webshots.com/photo/248209161/257008536hbujZt

Screen name: Vipergtj3
Password: pine1
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #15 ·
I think I found the culprit. The vacuum hose going to the fuel pressure regulator is missing. I cant make conclusions yet because theres still more investigating to do, but that would explain it.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #16 ·
New photos uploaded. Pic 1 is self explanitory. Pic 2, look at how the second compression ring is welded into place and how aluminum from the piston was dragged over it. Pic 3, along the bottom of the picture is where the reeds sit, what I dont understand is why there is damage in there too. Its all dinged up.
Pic 4, OUCH, all 4 corners of the piston skirt have broken off. All four of those pictures were from cylinder 1. Cyl 2 doesnt look nearly as bad. Ill take the bottom end apart tomorrow.

Username: Vipergtj3
Password: pine1

Pic 1
Pic 2
Pic 3
Pic 4
 

·
Registered
Joined
·
24 Posts
1BrokeCat said:
I think I found the culprit. The vacuum hose going to the fuel pressure regulator is missing. I cant make conclusions yet because theres still more investigating to do, but that would explain it.
there is no vacuum hose to regulator.I asked my arctic dealer and he said that is none.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #18 ·
Beemer said:
there is no vacuum hose to regulator.I asked my arctic dealer and he said that is none.
Why would there be a vac bung on it then?
 

·
Registered
Joined
·
24 Posts
there is only air in and out there!
I said the same thing why?
he said i don`t know but i`m sure that ther shell not be hose
there
 
1 - 20 of 21 Posts
Top