It's a sad day

[Slick]

--So, to recap--

-All 11-13 Polaris 800 engines need to replace pistons at 0 miles or more

--All 11-12 Polaris 800 crankshafts need updating or replacement with a 13 Fuji crank

So ,all take notice, Knifedge is REALLY hoping that his Cat performs even half decent with the 200 changes they made to it this year. Cause it's obvious to all that he' s suffering some major discomfort cause of his choice.
Some of us spend time hoping our sled works well, Some spend their time instead hoping the one they didn't buy has grief,
Karma usually fixes that.

 

[beamslayer]

Not all of them just some of them . I am hoping after all this it stays together I have not heard much bad about the cranks yet mostly the cylinder skirts cracking. If the 13s stay together I might even think about buying a 14 for the little lady next yr but I think it will be a 600.

 

[knifedge]

So ,all take notice, Knifedge is REALLY hoping that his Cat performs even half decent with the 200 changes they made to it this year. Cause it's obvious to all that he' s suffering some major discomfort cause of his choice.
Some of us spend time hoping our sled works well, Some spend their time instead hoping the one they didn't buy has grief,
Karma usually fixes that.

--Just want to ride and ride with reliable machines

 

[Going West]

--Just want to ride and ride with reliable machines

Better ride a yammy then cause my PC8 was the most unreliable sled I ever owned.

 

[knifedge]

--Nothing I ride is stock, as I like to build. However, I do ride with stock sleds.

--Good to see Polaris upgraded the crankshaft and thicker cylinder skirts on the 13 Pro.

 

[skibreeze]

I luv that A- AB what the hell does polaris do buy seconds from the piston mfg.
So are you saying you have .0055 to .0057 clearance why the .0002 difference is that taper in the bore ? I can not see the mag side all that clear for the last measurement .
Ski would you explain what you got going on there new cylinders,used cylinders, what did you use to measure everything with ect ?
Can someone explain how a piston skirt collapses ?

The pistons were measured by a machinist friend that owns a shop that builds race motors for a living. As far as the tools, the cylinder bore guage is about an $1,800 set. I thought that it would be cool to document the difference between a new motor and one that had been abused for 2,000 miles. As most of you guys know, I'm going to push my sled to the limits and beyond.

The differences are in fact differences in the bore diameter, the piston measurements were the largest measurements.

Thay way the piston collapse was explained to me is the sloppy bores allowing the piston to rock back and forth slapping the cylinder walls, eventually cracking the skirts and making the pistons smaller in the process.

I wanted to rebuild the '11 just because of the miles and the '12 to prevent the skirt issues that are starting to crop up. Now, I am very glad that I opened both of them up. The '12 is ready to go back together with new RK TEK pistons, the '11 will need to have the cylinder sent off for repair first

 

[beamslayer]

I thought you were going with RK Tech drop in kit ? Are those stock poo pistons ? Did they change mfg of pistons ?
The only reason I asked about the method of measurement is some guys use feeler gauges and pistons to measure bore .
Where did you end sending your cylinders ?

 

[skibreeze]

I am redoing both motors with RK TEK's pistons and heads, everything I posted up is the stock pistons. We wanted to show what Polaris is giving us as well as after only 2 seasons of use. There are a bunch of people with brand blinders on, they are convinced that their sleds are fine, when as you saw with the 3 motors we just tore down, they are ticking time bombs. Who knows how long the '11 would have run before it went BOOM!

I chose RK TEK because of his years of experience with 2 stroke motors. I am tired of rebuilding motors with the stock junk. I love the rest of the sled, like many, just need to get the motors up to snuff.

 

[Vfrtrader]

Thay way the piston collapse was explained to me is the sloppy bores allowing the piston to rock back and forth slapping the cylinder walls, eventually cracking the skirts and making the pistons smaller in the process.

So, Kelsey was right? The main problem with these motors is a sloppy piston. So, why in the name of Sam Hill does Polaris put sloppy pistons in these motors. Kelsey tryed to explain it, meeting standard fail rate or sometime, but I didn't get that. Could someone explain why Polaris would do such a stupid thing?

 

[skibreeze]

With my 08, it would stick pistons pretty easily, IMO now they are so loose to avoid seizing, which now creates the cracking skirts. That was never an issue old motors.

 

[Vfrtrader]

Cracked skirts or seizures, take your pick. OK, if we go with RKT or MTNTK piston kits will we see seizures like on the 08 Dragons? Which means the main problem is cooling, expanding/contracting cylinders. How can we increase cooling on these motors?

 

[Vfrtrader]

Beamslayer,

after inspection would you say the piston slap caused in cracking? You said the piston looked fine. No scuffing. No nicasil flaking. Could the crack be from an expanding/contracting cylinder? What your feelings on the cause?

 

[skibreeze]

I think the key here is by using a lighter forged piston, it can run proper tolerances to avoid seizing and avoid the collapsing issues that the stock pistons have. The 2 used motors we tore down had .009 to .010 clearances, this is double the recommended clearance and cause for the cracked skirts. This is just my opinion based on what I have seen and been told as I am not a mechanical engineer. Apparently there aren't many employed at Polaris either. lol

 

[beamslayer]

I could be way off base here but the more I think about it I come back to poor material (casting ) They are breaking in the intake port at the thinnest part . My pistons were only .0079 out no real sign of wear only slightly at the bottom edge,cylinders had no scuff marks either .
Than I ask myself why do some crack and some do not it seems to me if it where pistons clearance they all would be cracked . I am no expert on aluminum but I am pretty sure some will flex more than others .
Back in the day of the shovel head AMF harleys they used some substandard aluminum for their heads and we were seeing cracking in the ports not all of them but we seen a few.
Look at the cat and doo guys you ride with do they let them warm up--not the ones I ride with hell they do not even have temp gauges .
Only time is going to tell on all these piston kits and long rod motors the reason I liked the fix kit was it added that 1/4" plate to add some rigidity to the cases.
You asked for so here is my thoughts( poor materials + poor engineering = Kaboom

 

[Oregonsledder]

I could be way off base here but the more I think about it I come back to poor material (casting ) They are breaking in the intake port at the thinnest part . My pistons were only .0079 out no real sign of wear only slightly at the bottom edge,cylinders had no scuff marks either .
Than I ask myself why do some crack and some do not it seems to me if it where pistons clearance they all would be cracked . I am no expert on aluminum but I am pretty sure some will flex more than others .
Back in the day of the shovel head AMF harleys they used some substandard aluminum for their heads and we were seeing cracking in the ports not all of them but we seen a few.
Look at the cat and doo guys you ride with do they let them warm up--not the ones I ride with hell they do not even have temp gauges .
Only time is going to tell on all these piston kits and long rod motors the reason I liked the fix kit was it added that 1/4" plate to add some rigidity to the cases.
You asked for so here is my thoughts( poor materials + poor engineering = Kaboom

Ahhh yes... the shovel days from AMF. Now that was a time that would test brand loyalty!!

 

[beamslayer]

I still own a 56 pan that was the last of the good ones until the evos , oops of topic.

 

[doobie]

Just wanted to give a huuuuuge shout out to bruce's rv & polaris in medicine hat ab, for pulling threw with warranty on my cracked cylinder even know my warranty was expired. Along with the new cylinder, rkt DR pistons will be going in. Again thx trevor, ryan from bruces rv and kelsey for supplying the new pistons. My wallet is saved lol

 

[m8magicandmystery]

The pistons were measured by a machinist friend that owns a shop that builds race motors for a living. As far as the tools, the cylinder bore guage is about an $1,800 set. I thought that it would be cool to document the difference between a new motor and one that had been abused for 2,000 miles. As most of you guys know, I'm going to push my sled to the limits and beyond.

The differences are in fact differences in the bore diameter, the piston measurements were the largest measurements.

Thay way the piston collapse was explained to me is the sloppy bores allowing the piston to rock back and forth slapping the cylinder walls, eventually cracking the skirts and making the pistons smaller in the process.

I wanted to rebuild the '11 just because of the miles and the '12 to prevent the skirt issues that are starting to crop up. Now, I am very glad that I opened both of them up. The '12 is ready to go back together with new RK TEK pistons, the '11 will need to have the cylinder sent off for repair first

wtf...where the heck is the tape measure...???

 

[skibreeze]

lol, I was just going to eyeball the clearances, but I figured somebody would whine about that.

 

[RKT]

lol, I was just going to eyeball the clearances, but I figured somebody would whine about that.

Looks like about .018"..