Ski-Doo Snowmobiles Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
116 Posts
Discussion Starter · #1 ·
I set out to replace my rings tonight. I have 2000 miles on an 04 rev 800 and wanted to get it done just for piece of mind. I pulled the head and on the mag side, I found what looked like a ring had broke and done some damage to the head and piston. It dosent look like it did a lot of damage, but how much is to much to salvage the head? I pulled the rings and of coarse they are pitted but not broken. The reeds look fine also. What else could have caused this? I will add photos in the morning. Will I be able to reuse the head if it has minor damage?
 

·
ITs WINTER!
Joined
·
7,497 Posts
It would be nice to see the pictures!

As for the head pending a look at the pictures it can probably be cleaned up and reused.

Sounds to me like you will be in need of a new jug too...
 

·
ITs WINTER!
Joined
·
7,497 Posts
Head is salvagable, but it looks like that jug is done though. would you be able to get better pics of the jug?
 

·
Registered
Joined
·
116 Posts
The damage to the jug is only a discoloration. I cant feel a nick or scratch in the wall at all. The Ring locator pin is in place the rings are complete and unbroken, with the exception of the flaking but nothing big enough to do that kind of damage. The Reeds are intact and all the screws holding them in place are there. I dont know what could have caused this, any ideas? I am installing one new piston, new rings and cleaning up the head. Anything else I should be looking for?
Sorry I dont have better photos.
 

·
G MAN
Joined
·
5,381 Posts
Looks like mild detonation to me. Did you shave the heads or use a thinner base gasket? Lean the jetting out too much? Using a can? Maybe bad gas that was sitting around for a while?
 

·
ITs WINTER!
Joined
·
7,497 Posts
Thats not detonation, thats foreign object damage. Just gotta figure out what it was that got in there though...
 

·
Registered
Joined
·
116 Posts
Discussion Starter · #10 ·
The motor is stock, no shaving or thinner gasket. I dont have a can but I am running a Dynoport pipe.
 

·
Registered
Joined
·
116 Posts
Discussion Starter · #13 ·
Rev Kev said:
I would be looking at the piston, is the ring locator pin still pressed into the ring groove? Piston pin cir clip?? This motor definatly ate something, better find out what, to prevent a repeat on your fresh top end rebulid.
[snapback]691268[/snapback]​
Locator pin and both cir clips are in place. All the needle bearings are accounted for. Could anything have come lose from the carbs?
 

·
G MAN
Joined
·
5,381 Posts
REV112 said:
The motor is stock, no shaving or thinner gasket. I dont have a can but I am running a Dynoport pipe.
[snapback]691256[/snapback]​
That pipe leans the system out - especially in the mids (and Dynoport recommends 1-2 sizes larger on mains too IF you lake race). If you didn't shim your needles (or long WOT pulls) and ran bad low octane gas then detonation could easily cause that damage. And 06Gade that head looks exactly like mine after UBR accidently sent me 14.5:1 race domes and I ran it on pump gas. Mild detonation causes damage that looks like someone took a nail in a mallet and hit your head over and over - EXACTLY like the photo posted. Of course I'm just a clueless shadetree mechanic so feel free to talk with a motor shop!
The only thing in that motor was BAD GAS!

Have Fun,

G MAN
 

·
Registered
Joined
·
116 Posts
Discussion Starter · #18 ·
[/quote]

That pipe leans the system out - especially in the mids (and Dynoport recommends 1-2 sizes larger on mains too IF you lake race). If you didn't shim your needles (or long WOT pulls) and ran bad low octane gas then detonation could easily cause that damage. And 06Gade that head looks exactly like mine after UBR accidently sent me 14.5:1 race domes and I ran it on pump gas. Mild detonation causes damage that looks like someone took a nail in a mallet and hit your head over and over - EXACTLY like the photo posted. Of course I'm just a clueless shadetree mechanic so feel free to talk with a motor shop!
The only thing in that motor was BAD GAS!

Have Fun,

G MAN
[snapback]691342[/snapback]​
[/quote]

I was told my plugs look like I am running very rich
 

·
Registered
Joined
·
6 Posts
REV112 said:
I set out to replace my rings tonight. I have 2000 miles on an 04 rev 800 and wanted to get it done just for piece of mind. I pulled the head and on the mag side, I found what looked like a ring had broke and done some damage to the head and piston. It dosent look like it did a lot of damage, but how much is to much to salvage the head? I pulled the rings and of coarse they are pitted but not broken. The reeds look fine also. What else could have caused this? I will add photos in the morning. Will I be able to reuse the head if it has minor damage?
[snapback]689446[/snapback]​
better r&r crank may be a peace of bearing cage that was sucked up though the transfer port have see this many times on cranks i have rebult and cly. i have bored also check pipes and muffler for lose parts inside
 

·
G MAN
Joined
·
5,381 Posts
Your plugs can do that if you didn't lean out your oil pump cable. Most are giving 30:1 set at suggested cable free play when they should be at 45:1 which can make your plugs look like they're running rich even when you're lean. Another BRP screw-up I had to learn about on my own!

Cheers,

G

>>I was told my plugs look like I am running very rich<<
 
1 - 20 of 21 Posts
Top