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View Full Version : Detonation scarrs in pistons and rings on XP


bungeeguy
10-16-2009, 10:18 AM
I pulled my motor apart last night to put a top end, new SLP head and pipe on it and was shocked at what I found. I have a stock motor 08 800 XP with aprox 1800 miles. The mag side piston has tons of detonation scarrs in the piston and head, towards the exahuast side of the piston it is so bad that the piston is actual disintegrated almost to the ring. The primary side piston has three detonation warks in the piston and head. I ran premium fuel all winter and have stock jetting, any ideas?

Keithcat
10-16-2009, 11:09 AM
Post up a few photos.

I would be checking that side carb from top to bottom.

Keith

gpr
10-16-2009, 12:56 PM
What elevation do you ride at, and what jetting did you have in your carbs?

bonebreaker zack
10-16-2009, 01:05 PM
check your air intake boots. crack in mine caused that.

bungeeguy
10-16-2009, 03:38 PM
I ride between 5000-9000 ft. Carbs and jetting are stock, whatever skidoo sent. I was planning on jetting up to 490's and adding needle donuts with the SLP head and SLP exhaust system but for now I am going to take it to the dealer and see if my warranty will cover the damage.
I will post up any discoveries.

Arctic Thunder
10-16-2009, 04:07 PM
Jetting up isn't going to help with detonation.

I don't think. You need to run higher octane fuel to prevent detonation. Now if you are melting the piston then add fuel.

But again what I have found is if you are detonating you need to decrease the running compression or increase the octane.

Thunder

bungeeguy
10-16-2009, 04:16 PM
Jetting up isn't going to help with detonation.

I don't think. You need to run higher octane fuel to prevent detonation. Now if you are melting the piston then add fuel.

But again what I have found is if you are detonating you need to decrease the running compression or increase the octane.

Thunder

Back to the first post. Everything was stock on premium fuel. I WAS getting ready to add a NEW SLP head and SLP exhaust system but found all the damage on the piston, I haven't looked at them today but I am leaning towards a cracked carb boot or something because there is no reason i should have had any detonation so there is something weird going on.

XP2009
10-16-2009, 05:27 PM
X2 on artic thunders post. You never trully know what your getting at the pumps or exactly how long the fuel is in there. I have found increasing octane is the best way to prevent det.. ( provided your boots are o.k ).

Good luck.

Revdawg
10-16-2009, 08:24 PM
Just a thought but could it be from Snow ingestion? I my xp air box had alot of snow in it a few times last winter, the stock filter sucks and the valve dealy can let in snow to.

Arctic Thunder
10-16-2009, 08:31 PM
Ooops. didn't read that close enough. If this thing is bone stock then you might have a complaint.

Here is a picture of my M1000 piston, this one was bone stock but running lean due to some ECU problems. You can see the edge of the piston is gone down to the ring and the skirt is scuffed hard.

This looks like a det problem from the top when first looking at it but was clearly lean.

One day of bad gas could cause a lot of damage.

I always felt a splash of 100LL Ave gas was cheep insurance.

Thunder

http://i20.photobucket.com/albums/b250/Thunder900/Snowmobiling%202007-2008/martinsnowmobile010.jpg

http://i20.photobucket.com/albums/b250/Thunder900/Snowmobiling%202007-2008/martinsnowmobile009.jpg

http://i20.photobucket.com/albums/b250/Thunder900/Snowmobiling%202007-2008/martinsnowmobile001.jpg

bungeeguy
11-06-2009, 10:11 AM
Well I took it into Treasure Valley Motorsports, the skidoo dealer in Nampa and they thought it was detonation also but after looking at everything they said it was "foriegn debris in the combustion chamber" no one knows what it was or where it came from but they are covering it under warranty. :D

Cheynespub
11-06-2009, 12:26 PM
How much warranty did you have left?

bungeeguy
11-06-2009, 01:07 PM
Warranty expires this month November 30th.

triple7
11-06-2009, 02:30 PM
Ya, mine did something very similar to that. But it did it because the end of the ring broke off. I would be willing to bet you ate a ring pin, ring end, reed screw or something like that.

Cool that warranty covered it.

Jake

curt234
11-06-2009, 02:40 PM
Wonder why the knock sensor didn't pick it up.

1moretime
11-06-2009, 04:56 PM
1,110 miles on this 08 xp and the ring pin walked out of the piston, gorged the cylinder, the pin fell back into the piston. The ring gap then rotated to a port and finished it off. No warnings, went from full power to one jug in a split second. I rode it out about 13 miles and it stayed together. Reminded me of riding an Enticer from years ago.

Dang glad I bought the extended warranty last fall. $50 deductible.....$1100 warranty repair.

RMKcowboy
11-06-2009, 05:17 PM
1,110 miles on this 08 xp and the ring pin walked out of the piston, gorged the cylinder, the pin fell back into the piston. The ring gap then rotated to a port and finished it off. No warnings, went from full power to one jug in a split second. I rode it out about 13 miles and it stayed together. Reminded me of riding an Enticer from years ago.

Dang glad I bought the extended warranty last fall. $50 deductible.....$1100 warranty repair.
I think the same thing happened to my buddies 08 with 922 miles. I never got to see the damage, but what you described is exactly what he said happened to his. He had the Doo dealer rebuild it under warranty, then traded it in on a 2010 xp-x 800/163.