Piston Broke, common???

jjlrrw · Nov 22, 2014

Took my 2010 800HO out last night, first ride of the season, warmed it up as usual, as I was entering my yard after about 10 miles I heard a thunk, rode into garage engine didn't sound normal, shut it off remove pipe and here is the aftermath.

The upper ring locating pin is missing, I am thinking the ring spun around until the opening was in the exhaust port and got hung up. The cylinder is only damaged on the upper edge so I think all the carnage exited through the exhaust pipe.

Is this common or possible? I feel this is the cause and thinking one new cylinder and replace both pistons rings pins and bearing I should be good to go. I just want to make 100% sure this is the cause and not something else.
Picture are not the best the last one is a pic of the pin missing

Any suggestions on replacement pistons OEM, SPI, Wesco...

Thanks for any input

diggerdown · Nov 22, 2014

Probably caused by deto from old or low octane gas. As far as pistons go, oem are the strongest, wossner is probably the best after market, then SPI and weisco. Wossner run about $120each with the rings and wrist pins, that's through Bikeman there may be a cheaper source. SPI is the cheapest and equal quality to weisco. I would also put new wrist pin bearings in.

sledtahoe · Nov 22, 2014

looks lean

How does cylinder look was nikisal flaking off maybe. thats bad

jjlrrw · Nov 22, 2014

sledtahoe said:
How does cylinder look was nikisal flaking off maybe. thats bad

cylinder looks fine except for the area where the ring and piston are damage, the top ring was spun around to where the ends were in the exhaust port area the locating pin is not in the piston that would hold the ring from spinning around the piston.

backcountryislife · Nov 22, 2014

Just curious, how many miles on top end?

jjlrrw · Nov 22, 2014

backcountryislife said:
Just curious, how many miles on top end?

~8,100 miles

mikew5945 · Nov 22, 2014

backcountryislife said:
Just curious, how many miles on top end?

Awesome question....

jjlrrw said:
~8,100 miles

The answer equals the carnage.

Phizzer · Nov 23, 2014

jjlrrw said:
~8,100 miles

Damnnn....8100 miles!??! I would say your due for an overhaul...be a shame to put a fresh top end in and have the crank go out. I would definitely be checking it out when you pull the thing apart along with crank seals.

kidwoo · Nov 23, 2014

I love these motors.

That sucks JJ but considering how many miles you've gotten out of it, you're probably just adding the cost of a jug to what most of us would have done a few times before hitting that kind of mileage.

jjlrrw · Nov 24, 2014

kidwoo said:
I love these motors.

That sucks JJ but considering how many miles you've gotten out of it, you're probably just adding the cost of a jug to what most of us would have done a few times before hitting that kind of mileage.

Yep exactly, and it happen at the start of the season so good timing it rained all weekend snow is gone. I never thought of a locating pin shearing off so really wanted to know if it was common a known weak point. Every thing else looks very good.

I also have an '05 700 with 14,000 miles, had an y-pipe crack mid season last year causing a piston failure. I always inspected the Y-pipe prior to each season but neglected to do that last year...

Miles here in Mi are much different than in the mountains the '05 has 65% trails miles 35% off trail, my '10 40% trail, 60% off trail. Should have it back together by the end of the weekend going with OEM pistons.

Rixster · Nov 24, 2014

Millennium will repair and re-plate that cylinder for $200-300

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Piston Broke, common???

jjlrrw

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diggerdown

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sledtahoe

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jjlrrw

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backcountryislife

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jjlrrw

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mikew5945

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Phizzer

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kidwoo

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jjlrrw

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Rixster

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