How many miles on your 2011?

[007sevens]

I'll start by saying I've got 650 but I will also say this. When changing my head I've noticed that the piston clearance would appear sloppy. Have anyone else seen this?

 

[007sevens]

I must be the only guy who bought one last year on this site. LOL

 

[Mikew5j]

I have about the same mileage on mine and it runs perfect. Never had the head off so I couldn't comment about the piston clearance. Other than the clearance how did it look inside?

 

[007sevens]

I have about the same mileage on mine and it runs perfect. Never had the head off so I couldn't comment about the piston clearance. Other than the clearance how did it look inside?

Don't get me wrong, my runs flawless too, but for how long. I didn't go any farther than just the head. The cylinder walls looked good but from what I'm reading about the older motors (2008-2009) is that the piston would rock, scuffing the exhaust side top of the piston and the skirt on the bottom of the intake side. The 2011 motors have the same pistons as the updated 2008-2010 motors but different part numbers for the mono block. So this raised some questions when I seen the loose pistons. I am now going to pull it down to the base to see if there is any scuffing of the pistons and to check clearance.

 

[RUDY]

Haven't heard any real issue's with the 011's like the 08-10's...hope all is good with the sled,do keep us posted.

 

[Mikew5j]

Don't get me wrong, my runs flawless too, but for how long. I didn't go any farther than just the head. The cylinder walls looked good but from what I'm reading about the older motors (2008-2009) is that the piston would rock, scuffing the exhaust side top of the piston and the skirt on the bottom of the intake side. The 2011 motors have the same pistons as the updated 2008-2010 motors but different part numbers for the mono block. So this raised some questions when I seen the loose pistons. I am now going to pull it down to the base to see if there is any scuffing of the pistons and to check clearance.

Piston clearance was only one of the issues that lead to the problems with the 2008-2010 motors before and after the update. Although it probably didn't help I don't think clearance was a fatal issue. I think the crank case injectors, port timing, exhaust valves, and mapping played more of a roll.

Here is a quote from Dynotech after running the new 2011...

Casey has indicated that the cylinders’ port timing is more conservative (ie: lower) than the Dragon 800. Remember, Casey made way more power on his D8 with raised ports compare to stock. So why would the ProR 800 have lowered cylinders? Emissions? Big torque and HP off the bottom? Drivability?

Or could it be, at least in part, the need to have ample cylinder pressure to slam those exhaust valves open, exactly when commanded? As I indicated in the prior discussion here about the possible cause of the mysterious lean midrange that has plagued many Dragon 800 owners, the mechanical cylinder pressure operated exhaust valves may be the culprit! Remember, if those valves stay closed when the ECU thinks they are open, airflow will climb with insufficient fuel flow and leanout/ stumble/ deto/ seizure can occur. Late opening valves can cause airflow to increase as revs climb—the opposite of what we might expect! Perhaps, by lowering exhaust ports a bunch, the part throttle cylinder pressure reaching the exhaust valves is many times higher than we experienced with the Dragon 800s. This could make those pesky pressure operated exhaust valves slam open on demand, eliminating the strange and inconsistent lean midrange that may have cost Polaris millions in warranty claims and gave Dragon 800s—an otherwise excellent machine—a bad rap. So did Polaris just sacrifice a few ProR 800 HP in exchange for perfect synchronization of exhaust valves and ECU commands?

Casey Mulkins is planning to create a batch of cylinder shims to match the port timing of the powerful Dragon 800 that he rode last year. He will also need to machine the stock heads to compensate, perhaps necessitating dropping the combustion chambers down into the cylinders to maintain that nice tight squish

Anyway, just my opinion. So far the 2011's have been fairly solid by most reports.

 

[007sevens]

I've read that same write up, but what it doesn't say is that these test sleds are short tracks not designed for the mountains and have different port timing.

I agree that Pro's have been solid but for how long. Which is why I was asking if anybody had a lot of miles. A piston that is rocking in the cylinder won't last forever and might not stand up to high Hp upgrades. I agree that if you leave it stock it might last a long time but if your looking for every bit of hp out of the engine this is one area worth looking at.

The pistons were also sized smaller because polaris leaned out the mid range. They did this to meet emissions, causing the piston to over heat and enlarge causing a tighter piston to seize.

 

[007sevens]

Here is a interesting read I found 800 cfi Piston Replacement [Archive] - SnoWest Snowmobile Forum

 

[Warhawk]

Don't get me wrong, my runs flawless too, but for how long. I didn't go any farther than just the head. The cylinder walls looked good but from what I'm reading about the older motors (2008-2009) is that the piston would rock, scuffing the exhaust side top of the piston and the skirt on the bottom of the intake side. The 2011 motors have the same pistons as the updated 2008-2010 motors but different part numbers for the mono block. So this raised some questions when I seen the loose pistons. I am now going to pull it down to the base to see if there is any scuffing of the pistons and to check clearance.

WHY are you taking the head off? Doing mods?

 

[Mikew5j]

I've read that same write up, but what it doesn't say is that these test sleds are short tracks not designed for the mountains and have different port timing.

I agree that Pro's have been solid but for how long. Which is why I was asking if anybody had a lot of miles. A piston that is rocking in the cylinder won't last forever and might not stand up to high Hp upgrades. I agree that if you leave it stock it might last a long time but if your looking for every bit of hp out of the engine this is one area worth looking at.

The pistons were also sized bigger because polaris leaned out the mid range. They did this to meet emissions, causing the piston to over heat and enlarge causing a tighter piston to seize.

I wasn't aware of the port timing difference on the short track sleds. I thought they were all the same. Thanks for the post.

 

[wolflake06]

I've got 1450 miles on mine, haven't had any issues on it yet......

 

[007sevens]

I've got 1450 miles on mine, haven't had any issues on it yet......

now that's worth something. I wonder if the piston changes that much when its warm that it comes within tolerance.

 

[007sevens]

WHY are you taking the head off? Doing mods?

Yes, I'm putting on a power addiction 13.1 head. This should help with some of the lost ponies at elevation.

 

[flying frenchman]

I got 1150 hard miles. When I rode it the other day, there was a funny noise coming from the engine. I have to get the oil line checked out and will get it checked out.

 

[007sevens]

I got 1150 hard miles. When I rode it the other day, there was a funny noise coming from the engine. I have to get the oil line checked out and will get it checked out.

If you got a 1150 miles, I don't think you have an oil line problem. That recall was to check for possible oil line pinch. I think you would have seen issues way before now.

 

[flying frenchman]

Got a letter in the mail they want to check possible oil line rubbing on bulhead issue. They're supposed to tie it up so it don't rub.

 

[HotShotHarry]

950 miles last season with no issues- motor wise.

 

[007sevens]

I've found minor scuffing on the intake side of the piston but none on the exhaust side. The cylinders look great, you can still see the cross hatch patterns. The clearances of the piston raise some question with me and I will need to make some phones calls on this. I found the clearances of the skirt to cylinder to be .005 thousands of an inch and I found that the top of the piston is .030 thousands of an inch which would explain the sloppy piston. I not sure why Polaris would do this but I intend to find out.

 

[RUDY]

I've found minor scuffing on the intake side of the piston but none on the exhaust side. The cylinders look great, you can still see the cross hatch patterns. The clearances of the piston raise some question with me and I will need to make some phones calls on this. I found the clearances of the skirt to cylinder to be .005 thousands of an inch and I found that the top of the piston is .030 thousands of an inch which would explain the sloppy piston. I not sure why Polaris would do this but I intend to find out.

lets us know what u find out,i'm sure alot more guys are interested

 

[Warhawk]

You have to be kidding me. You shouldn't even be putting a cylinder head on this sled. You don't even have a clue about engines. This is the kind of thread that gives a engine a bad name.
Somebody who doesn't have a clue about HOW THEY WORK.


STOP well your ahead.