Piston visual inspection

[Snowbird11]

I'm trying do decide if I have a problem and how soon it may need to be addressed. I have an 08 800 dragon with about 850 miles on it. the 2010 update was installed around 400 miles ago. i pulled the exhaust valves today to have a look and am noticing some of the coating has been worn though on both pistons (most notable at top and bottom of pistons). there is light scuffing on the pto side except for one hard scratch in the far left view in the pto piston, about where the exhaust valve may make contact with the piston. it is most pronounced in the middle half of the piston when turning the engine over.

is the coating wearing off typical on these updated double ring pistons. is it due to increased friction and heat from a second ring?

so, i'm starting to wonder if i need to pull it apart and have a look. i'm thinking i need to have the cylinder skirts looked over for cracks and possibly renicked if it's out of spec or damaged.

i'm pretty new to two stroke engine work and only know what i've read here. so, what would you do if it were your sled?

 

[Snowbird11]

Here are a few pics of the PTO side.

 

[sledhed]

Looks decent to me, I would run it for a while yet if it were any engine other than the 800 of this generation... I have an 08 Dragon 800 1600 miles and about 500 on the update and I am seriously considering the "fix kit" from mtn tek / PMS Polaris just for peace of mind...

Kind of an unrelated issue but i had my 2002 Skidoo 800 drop a piston skirt (cracked and broke off I am sure) and it basically destroyed that engine, put a hole in the bottom of the crankcase and lots of little pieces of aluminum throughout... don't want to have that happen again. Luckily was relatively close to the road. That engine tended to crack skirts around 1000 - 1200 miles I think I had 1500 and should have replaced them...

 

[GKR]

Ticking time bomb if you ask me. The evidence you see screams fatigued piston and skirt breakage is generally the result. I just did the fix kit and posted similar pics. The wear bands near the top and bottom are wear marks from piston rocking in the bore. The gouge from the exhaust valve is bad. You are far enough into it now do the fix kit and be done. It will or should last much longer. Search my posts recently, you will find a good thread with pics and all my measurement specs. You should measure your piston to cylinder measurement. That will likely tell you it's already way beyond the wear spec and very sloppy. The risk if you don't fix it now is usually catostrophic and typically fails the case if a skirt breaks, then the cost goes up fast. There are lots of threads on the fix kit, it is a good solution for this problem and I am very happy with it so far.

 

[GKR]

On second look I see you are not apart yet so tougher decision to make. I did the same and I'm glad I decided to do it. If you check my thread you will see that my exhaust sides looked very similar but my intake sides had significant damage on the lower skirt. Here"s the link.
http://www.snowestonline.com/forum/showthread.php?t=300905

 

[Snowbird11]

here's a quick shot after the monoblock was off.

 

[GKR]

How do the intake sides look? You can see the wear band down on the bottom of the skirt all the way across the mag side piston. This is from the rocking action of the loose fit and is where skirt failure will occur.

 

[Snowbird11]

How do the intake sides look? You can see the wear band down on the bottom of the skirt all the way across the mag side piston. This is from the rocking action of the loose fit and is where skirt failure will occur.

it doesn't look like it had too much time to do damage over there either. i'll snap a pic tomorrow night when i pull the pistons. the fix kit should be here by then.

 

[Snowbird11]

here's the intake side of the PTO piston. it doesn't look like eminent failure but i'm still glad it's getting down now rather than after a skirt breaks of.

my fix kit came in yesterday but they forgot to put one wrist pin in the box. hopefully it'll get here tomorrow.