Opinion Mr. Viper 700 Pistion Diagnosis

SRX_700

SRX_700

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Joined
Jan 14, 2011
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Age
55
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Toronto
Motor sized and here are some pics of the piston. What is your diagnosis? Want to sort out why this happened before I rebuild?

(sorry it's from a Ski Poo but the wealth of knowledge on this board is second to none).
 

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is it from a ski-doo ??? what type of sled does it come ? not sure how u call it but some doo sled have a fuel ritch lean gadget with altitude ..........they seem not to work very good ?????????????????
 
modsrx said:
is it from a ski-doo ??? what type of sled does it come ? not sure how u call it but some doo sled have a fuel ritch lean gadget with altitude ..........they seem not to work very good ?????????????????
Click to expand...

Mach Z 1000 - 2005 with 5,500 miles on it. It's called a Boon Docker and I do not have one.
 
Calling it lean due to the grey looking carbon and large hot spot under the piston. Not hot enough to cause a melt down, but hot enough to cause the piston to swell and seize.
 
Sorry, I didn't mean to be negative. It's just important to acknowledge that these machines were known to have issues. At the end of the day, it may help finding the reason for the burn down.
 
max17ime said:
Sorry, I didn't mean to be negative. It's just important to acknowledge that these machines were known to have issues. At the end of the day, it may help finding the reason for the burn down.
Click to expand...

I can roll with the punches. Still need some more opinions on what is going on with the motor.
 
Need to do a leak down test, but since you have it torn down that's not possible unless you put it back together. What side piston went or was it both? What's the story on how it seized, were you running the lake, idling in the garage, what happened?
 
Black spot underside looks like piston crown got too hot. Cooling issue or jetted lean. Unless scuffs are on intake side tun you have an oil problem. assuming ales is stock. No advanced timing or high comp. Could be too hot spark plug range
 
Both sides look the same. I bought it with this issue and ran it for 500 more miles before the pistons started sticking. My guess is detonation caused excessive heat which burnt the oil. Just not sure why the detonation except for incorrect squish, bad/low quality fuel, etc.
 
If the entire piston is scuffed that could be piston to cylinder wall clearance issue. Cylinder/piston out of round or out of Max wear spec.
 
Scuffs just on intake side. Both pistons look the same. Fuel injected SDI 995 motor. Signs of detonation are on the piston pin. Used stock plug. Motor is completely stock but previous owner had a BRP can which I took out. Oil setting set to stock with BRP Synthetic used.

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Ok try replacing the oil injectors on the back of your crank case. I would say there is definetly an oil problem. Everytime I do a skidoo motor I replace these injectors. You'll need to carefully heat the case around the Injector because they are press fit. Replace with green loctite/retaining compound...ive seen a ton of ****ed injectors on skidoo motors if this era. When you get them out try blowing some air through them and you will see what I mean. I would definetly make sure the sled is jetted proper as the pictures lool like a lean problem... and check your cooling system. Definetly check all measurements when doing top end to make sure clearances are ok... Ring gap, piston to cylinder wall etc...only other thing I can suggest with that sled is to send your clutches out for precision ballancing. They were pretty out of wack from factory. My two cents...You can try this its somewhere to start. Hopefully Mr viper will chime in. Good luck!
 
Fuel injected. Injectors are out for cleaning and flow testing. All scuffs are on the intake side. Exhaust side of the piston looks normal.
 
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