Mag Piston Burndown 10 D8

die hard poo · May 5, 2011

Hey guys, I got a question, I burned my Mag Piston on my 10 D8 while rescuing my Pro with a broken Primary(read full story on the PRO-RIDE Section).

My question is this what do you think caused it to happen.

Sled has 750 miles, original motor, no issues at all so far. It has the PCV DTR map since basically new. Always warmed up to 100*+ before taking off. It happened after riding in 15 miles double person with mixed throttle trying not to have too much mid throttle. Letting it sit for a few hours and then taking off for another 2 miles and then fried the Mag piston. I was able to get it freed up and ride out the 15 miles with 1 cylinder and the Mag cylinder's spark plug unplugged all the way to the truck. Crank case looks great. I plan on installing wiseco's two piston kit. Any ideas how this could happen only to the Mag side? PTO looks perfect, even after like an hour of WOT.

Hawkster · May 5, 2011

Better yet what did the shop tell you ?? whe're dieing to hear their comments ?

akrevrider · May 5, 2011

D8 burndown

Could it be an airleak that caused it? Are you going to order The Fix Kit from Mtn Tech for the replacement pistons?

milehighassassin · May 6, 2011

Wondering myself. It certainly looks like that one side got hot.

modrmk · May 6, 2011

What fuel were you running? I have had two 09 Dragons come into the shop this year with the same thing. They were both running ethanol fuel. I believe that with the cleaning properties of ethanol, it knocked some gunk loose in the fuel system, temporarily plugging an injector and causing a lean burn down. We are running Star Tron ethanol treatment in all of our sleds now and also in customers sleds and not having any more issues.

2XM3 · May 6, 2011

Heat, detonation on this one. Man you torched that piston :face-icon-small-sho

umm i'd check both your injectors on that side 4 sure

sled_guy · May 6, 2011

Pro down with broken clutch, fry your dragon rescuing it... next time I'll kick you in the balls for free.

That is a lean burn down. Start checking the fuel system. Could it have iced up while it was sitting and then plugged/partially plugged the injector?

sled_guy

die hard poo · May 6, 2011

akrevrider said:
Could it be an airleak that caused it? Are you going to order The Fix Kit from Mtn Tech for the replacement pistons?

Ya that is what I am wondering, I will check the tb boots before it goes back together. I just spent some time reading about the"Fix" and it seems promising. Wonder if this would pertain to the pros? I am trying to sell the Dragon, cause I snowchecked a 12' Assault and there is no need for the Dragon anymore. I think I will just put the wiseco balanced piston kit in and have the cylinders honed.

modrmk said:
What fuel were you running? I have had two 09 Dragons come into the shop this year with the same thing. They were both running ethanol fuel. I believe that with the cleaning properties of ethanol, it knocked some gunk loose in the fuel system, temporarily plugging an injector and causing a lean burn down. We are running Star Tron ethanol treatment in all of our sleds now and also in customers sleds and not having any more issues.

I was running 90 octane non-ethanol fuel, we don't have ethanol fuel in the AK. But I have not changed the fuel filter ever (750 miles), but it is weird that the PTO Piston is perfect. Might be an injector issue.

2XM3 said:
Heat, detonation on this one. Man you torched that piston :face-icon-small-sho

umm i'd check both your injectors on that side 4 sure

LOL ya I have never eroded the piston behind both rings before and then blow a hole on the skirt of the piston! So how do you check for a bad or plugged injector?

sled_guy said:
Pro down with broken clutch, fry your dragon rescuing it... next time I'll kick you in the balls for free.
Go for it man, I was sure feeling like I was already got kicked in the balls from Polaris! I sure was thinking twice about Polaris, especially after my Rzr S decided to run like crap on me right after this all happened!

That is a lean burn down. Start checking the fuel system. Could it have iced up while it was sitting and then plugged/partially plugged the injector?

sled_guy

Na, it was like 50-55* that day, but it could be an other fueling issue.

xc6rider · May 6, 2011

PTO even looks fairly lean from what I can see. Could just be the way the picture is taking though.

akrevrider · May 6, 2011

die hard poo said:
Ya that is what I am wondering, I will check the tb boots before it goes back together. I just spent some time reading about the"Fix" and it seems promising. Wonder if this would pertain to the pros? I am trying to sell the Dragon, cause I snowchecked a 12' Assault and there is no need for the Dragon anymore. I think I will just put the wiseco balanced piston kit in and have the cylinders honed.

Give Shawn at MTNTK Performance (208-652-7738) to ask question on what models it will work on and to place an order for one of their kits. If the cylinder is still good then hone them w/ a hardened hone to seat the rings.

My sled is still running but I'm going with "The Fix" to make sure it is good for next season and the next rider that I sell it to. I'll post up pics of the pistons when I pull them. They look good thru the Y-pipe but I'm betting they are scuffed on the skirts after 400 plus miles on the Polaris update.

Glad you recovered your Pro off the glacier.. Awesome job!

Keep us posted on the Dragon repair.

akrevrider

Polarisrocks · May 7, 2011

Hate to say it but lean burn downs are almost always holes in the center of the piston.. if the front edge of the piston in eroded off and looks like sand paper, it detonation.. serious detonation would be my diagnosis.. I havent see a hole bunch of wash on any of the dragon pistons I have seen, but the plugs look very good.

xc6rider · May 7, 2011

I don't doubt their was detonation, but I'd think it was caused by a lean condition.
I've seen more holes caused by advanced timing, and too hot plugs. Or sudden air leaks. Things that produce a ton of heat on the crown, and quickly.

But, every engine is so much different, and always changing. Two different pistons can burn up differently in the same conditions.

Either way, I believe it is definitly a fuel issue. Whether not enough, or poor quality.

Butta · May 8, 2011

I'd have your cylinders checked for roundness....chances are if it got that hot, you'll find the cylinders are trashed.....egg shaped...

2XM3 · May 8, 2011

most all shops doing any high performance work and some regular auto shops have the machine that will cycle and clean the injectors. The best machine will clean them and print out a before and after flow rate. We used brucato machine in florida for all our racing mercury outboard injectors.

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Mag Piston Burndown 10 D8

die hard poo

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Hawkster

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akrevrider

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milehighassassin

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modrmk

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2XM3

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die hard poo

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