What causes this?
- Thread starter scott_b
- Start date
Actually, I've hear that's the worse thing for the motor. Sitting at a constant speed. If you find that one spot where the sled is running a little lean, and you hold it there, that's what happens. You could have had other issues to contribute to it I'm sure, but the 'hold' at a constant speed is one of those contributors.
toddspolaris
Member
seen some of those years do that. what does the jug look like? rebuild the top end with wiseco pistons and it won't happen again.
fyi - my bro-in-law had a similar issue season-end of 07-08. approx the same sled.....a twin 600.....yamaha circa 97 or 98. rebuilt in summer of 08. 2 more trips in the tank early season of 08-09. sled got kicked to the curb in jan 09. he rode my spare the rest of the season.
looks lean to me. Would put much into the ring being embedded. Strange things happen once burn down starts...... Doo 800 I am rebuilding now has not one ball bearing in the iner bearing on the p.t.o. side. but couldn't find one in the motor either. Outside bearing is still intact. Shot but intact. Managed to take out my piston on the way but the jug is still salvagable (but since I am putting so much into it a new jug is on the way). Seen crazy things happen once bad starts....
Were the rings ever replaced in the sled before?
Looks like it was running plenty rich, so I will say that the rings were bad, causing the piston to slap around and enlarging the bore. The ringe finally lost their mark in the groove, and came out and didn't have anywhere to go, so they took the path of least resistance and took out the jug and piston.
timing is an issue. On Yammy Vipers, they have a huge timing spike around 35-50 mph, and this will actually burn them down.
Polaris
Looks like it was running plenty rich, so I will say that the rings were bad, causing the piston to slap around and enlarging the bore. The ringe finally lost their mark in the groove, and came out and didn't have anywhere to go, so they took the path of least resistance and took out the jug and piston.
timing is an issue. On Yammy Vipers, they have a huge timing spike around 35-50 mph, and this will actually burn them down.
Polaris
6mile
Member
A bit hard to tell from the pic, but the way the ring is turned and bent down one would have to say that the the locating pin for the ring worked it's way out and allowed the ring to rotate and catch on a transfer port.
What caused the locating pin to come out you may ask? Detonation plain and simple.
You say that there are not any signs of the sled running lean, but if you look at the top of the piston there are no wash marks at all. It was running lean for sure. If you put it back together, be sure to clean your carbs really good and replace the jets.
What caused the locating pin to come out you may ask? Detonation plain and simple.
You say that there are not any signs of the sled running lean, but if you look at the top of the piston there are no wash marks at all. It was running lean for sure. If you put it back together, be sure to clean your carbs really good and replace the jets.
Todd,
Why would you say rebuild it with a wiseco and it won't happen again? You don't know all of the facts are are spreading worthless information. Yamaha Pistons are very durable and well built. I guess I can see this statement coming from a Polaris person as Polaris had a major problem with piston skirts failing on their pistons, and I think they still have that issue although it isn't as bad as it was before.
toddspolaris
Member
maxwell, rebuilt probably 10 of those in my years of working at the yamaha dealer in the days. I saw many pins come out of some of those pistons for no reason allowing the ring to spin and catch. We rebuilt with wisecos and never had any problems after the fact. I 'm only stating what I have expeirenced with those machines in those days, I never said yamaha pistons were junk, did I. No. Thank you Todd. Oh and by the way I own 2 skidoos, one arctic cat and one polaris
polarisrider1
New member
Maxwell, why the Polaris slam? Why do my Polaris sleds never blow up? I beat the snot out of them! Must be the oil. lol (indy 500 you did not hear that, your switchy is pampered).lol
Canola oil right?
toddspolaris
Member
thanks Polarisrider1, just made me feel a whole lot better. I didn't think I slammed any body. He must be having a bad day. Not me baby, its Friday. Indy, you have lots of extras, have fun
I don't think the dome wash is a reliable indicator on this piston since we then rode the sled 40 miles back home on one lung. I was saying it didn't appear lean based on the plug when we pulled it right after it lost power.
Guess we will rebuild it, clean the carbs well and hope for the best.
[/QUOTE=6mile;89136]
You say that there are not any signs of the sled running lean, but if you look at the top of the piston there are no wash marks at all. It was running lean for sure. If you put it back together, be sure to clean your carbs really good and replace the jets.[/QUOTE]
Guess we will rebuild it, clean the carbs well and hope for the best.
[/QUOTE=6mile;89136]
You say that there are not any signs of the sled running lean, but if you look at the top of the piston there are no wash marks at all. It was running lean for sure. If you put it back together, be sure to clean your carbs really good and replace the jets.[/QUOTE]
it wasn't a slam on Polaris, I was simply stating a fact that in the 90's and early 2000 era Polaris had some issues with the piston skirts craking and breaking off.
I myself have owned a few Polaris and have seen this issue in two of my sleds and one of my two ATV's. The other ATV is running fine with over 9k on the odometer.
When someone says to use wiseco pistons and you will never have a problem again, is usually not a complete and true statement, and can send some in the wrong direction.
ToddsPolaris,
I apologize, I was assuming you had Polaris due to your username.
Yes, pins do fall out of the pistons for unkown reasons, and I think we can all agree that the ring spun in the groove and caught something (a transfer port, inlet port, exhaust port and broke).
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