...So I opened up the engine of my EX 570

Oyvind Ryeng

Oyvind Ryeng

New member
Joined
Sep 11, 2004
Messages
55
Age
41
Location
Norway
Website
oyvindryeng.net
"Well, there's your problem!"

EDIT:
Skirt has broken clean off the piston and ruined my crank and a rod bearing (rod has 1/8 inch vertical play), piston has hot-seized / expanded into the cylinder wall; requires overboring and rehoning, piece of the skirt or piece of piston ring has been trapped inside the combustion chamber and wrecked havoc on to the piston and head. Probable cause: Leaking PTO crank seal (fresh air has entered this cylinder and caused a lean condition) or a carburetor jet has been plugged by a small foreign object. Depression fills the room.
 

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ahh, that'll buff right out ;) that sucks man. maybe time for a few upgraded parts while you are in there :)
 
Thanks for your sympathies, guys; it means alot to me.

03viperguy said:
maybe time for a few upgraded parts while you are in there :)
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Yes, I was thinking something along those lines. Especially when considering a complete top-end kit from Wiseco with forged pistons is USD$246 + shipping and toll while a single stock piston from my local Yamaha dealer is USD$283, and that is without rings, pin, clips, top rod bearing and gaskets. We live in a strange world; seeing as how I can by a better product for less money, have it shipped half-way around the world, pay the tolls on the product and it'll still cost less than picking it up from my local dealer. The wait is approximatly the same also, seeing as how the Wisecos will be shipped by air and my dealer don't have the parts in question in stock. The same applies to my now sold '87 Honda Accord. Most parts baught, shipped and tolled from the good 'ol US of A cost me 1/3 of what my local dealership wanted when all was said and done. This might be related to the fact that many Honda passenger cars and many of their parts are actually made in plants in the USA, while the dealers in Europe has to buy parts made in, and from Japan.



ejcamaro said:
How many kilometers were on the sled Oyvind?
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Honestly, I can't say for sure. The speedometer drive on the driveshaft stopped working many years ago according to the previous owner. The odometer has stopped counting at ~12,500 kilometres, and the sled has been ridden close to the same distance these last few years. So the best guess is in the neighborhood of 25,000 quite rough kilometres. I'm confident an AC or Pol would have given up the ghost a long time ago; but one can never know for sure - I certinly have great confidence in the reliability of Yamaha snowmobiles despite this 'minor setback'.



qwinnraptor said:
a little bit of over revving.
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Quite possible. The side cover on the PTO side are loose and the grommets on the bottom side are worn out/torn open so snow can hit the drive belt and clutches. Of course, I'm aware of this problem and release the gas immidiately if I sense the clutch(es) slipping.



TimeBomb said:
must have made one heck of a noise when she went.
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I would not know; I was not the one riding it when the damage occured. The sled was sitting in storage at a so-called 'friends' house. It was in good working order when I left it there and broken when I picked it up after the first snow had fallen Fall 2004.
 
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wow, so-called-friend sounds like a great guy.......... :( hope all goes back together well for you in the end :)
 
Ouch...

Ahhhh Just add a new set of Rings ... she'll seat in...

All Joking aside.. That sucks...

I still have to see what mine is reving at and see if I am over reving myself as I just did some mods (new Pipes, jetting, clutching, helix etc...) But have yet to get a really good open area to check to see hows she's burning a set of plugs and reving...
 
It may have been that the rod bearing was the original problem. The pieces of it could have caused the rest of the damage.
 
i say over revving because i did the exact same thing last year to my v-max.

tore the head and jugs off and the skirts were shattered.
thats more than likely what happened to make your piston skirts break, or so ive been told by everyone around here.

good luck fixing her.
 
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