850 gone down already??

[1Mike900]

This is an absolute bummer, I was hoping this engine would set the bar! Then Cat would come out with a 850+ engine and re-establish it! The 74 MM stroke looked like the right way to go and just increase bore to go larger! Too bad there are a few overlooked items, but I am sure it will be corrected due to posts! Just think if you make it thru to the spring, just hammer it home and maybe you will have a new engine for next yr! Oh a question for Dan, what is the cylinder plating thickness that is applied before hone? I do recall you remove about another .0003 -.0004 to achieve final finish? Just wondering what is left of plating thickness? And is it .0003 -.0004 of surface or total dia. removal? Have a happy holiday! Mike

 

[Devilmanak]

Mods - Is there any way to start a thread with a "poll" that could track engine failures based on failure, delivery date, and delivery location? I would be very interested to see, based on the fact that Poo has had issues getting sleds to people.

 

[BeartoothBaron]

I don’t know for fact that Polaris does it this way, but would bet money that they do... “Test” units usually go through different iterations. This would be a general progression. Different manufacturers and even different projects will vary slightly, but the general theory is likely the same. There are often stages in between what I’m laying out below, but this would cover the higher level steps.

Step 1: skunk works prototype, “mule”. Kind of a proof of concept. Hand built, using non-production procedures and components. A lot of times the “testing” done here is more around design concepts and not so much around repair frequency tracking.

Step 2: full prototype. This is where you’d have maybe 70-80% final product components and some level of production procedures, but not many. These are the units that would go through the majority of the testing and failure analysis. Many engineering changes and component changes based on what they learn. The units are updated periodically with new designs and testing continues

Step 3: pilot units. This is as much a test of manufacturing process as it is anything else. The product is 95% or more “final” product. These units will have some specific test requirements and used for auditing numerous aspects of the project. Everything is built in the production environment. Very few changes to the product can be made at this point. If there are, step 2 was a failure and there will be a delay in the project for additional test needs.

To say engineers working on these projects don’t have real world experience is complete ignorance. Yes, some (many) design engineers fit that label, but design engineering is only one piece. Test engineers are often mechanics, engineers, riders, users, etc... they don’t sit behind a computer screen in CAD all day, but they can... there are also technical service personnel that are very involved in these projects that bring data from past experience, serviceability, warranty issues, etc.

There is a lot of hyperbole in this thread. What Dan proposes in all these situations is what we consider a “10X” fix. Basically, spend any amount of money, over engineer it, and push out a fix that is almost certain to never fail (10x stronger/better than it needs to be). IF Polaris starts experiencing a 20+% failure rate throughout the entire vehicle park, that might be something they consider. But I doubt that happens or the project wouldn’t have been released. If they see failures, they are going to go into failure analysis and fix the root cause of the issue...not just do a 10X fix because that changes down steam variables.

I'm betting you're pretty close to what actually happens in terms of the R&D of a new motor. I'd speculate that the "step 2" motors are the ones that have been running for years that Polaris bragged on so much at the introduction, and are a better built motor than at least some of the production 850s. They're the ones that are going to be hand-checked, honed, finished, and all, with a lot of attention to detail. It's quite possible Polaris did a very good job designing the engine, and the "we've had hundreds of prototypes running for thousands of miles a piece" claims are pretty accurate. But it's quite possible that the production engines are actually worse. It could be teething issues involving cylinder finishes, assembly procedures, and such concerns that'll be quickly worked out. It could be that the 850 has some design weaknesses that make assembly errors more likely and/or fatal. Or maybe a handful of failures are being blown out of proportion; without tearing down at least a dozen motors off the line or waiting a few months, I don't think anyone can be certain yet. I definitely agree that it's unfair to say the engineers screwed the pooch until we have more hard numbers on the failure rate.

As far as Dan's "fixes," they may be overkill for an OEM, but they're the sort of thing I would definitely spend money on. I might be an outlier in that I like wrenching on my own stuff, but imagine the following: I buy a blown Pro for $2K. I send the motor to Dan to be built into a bulletproof long rod motor – another $3.5K. I spend another $2k going through all the consumables (motor mounts, bearings, bushings, etc.) and any essential upgrades. I've spent half the price of a new 850; I have a sled that's not quite as good to ride, but significantly less likely to go down on me (wait, that's what she said), and I have more money in my pocket for other things.

Maybe it's just me, but I don't mind spending more on something significantly less likely to fail. It takes up most of the weekend for me to get in a good day of riding, and I don't go every weekend even though I'm closer than many. My current sled has been pretty "pull and go" (knock on wood), and that means a lot to me. The kind of refinement Dan's talking about would add maybe $500 to the price of a new 850; you might not get to the same level in mass production, but I'm sure we'd agree Polaris has room for improvement. Let's bump that number up to $1000, call it markup. Now, show of hands, who'd pay $1000 more for an "850 bulletproof" that was brought up to Dan's standards? If I'm paying $15k for a new sled already, that's not a hard choice for me...

 

[BILTIT]

Thats exactly what i did, bought a blown pro and had dan build the engine.

Now, if only you could buy a blown 850 axys for a couple grand

Sent from my SM-A530W using Tapatalk

 

[Ktm Fanatic]

Was ripping down the trail on the way to what looked like a good day of riding. Cruising along and the motor falls on its face and shuts off. Long story short 5.3 hrs on motor, crank bearing.[/

Did you slit the cases to confirm a failed crank bearing ?

 

[Matte Murder]

To all you guys with new 850s that have blown up I feel for you. That’s really got to be a gut punch, especially if you are a 1 sled guy, only buy new once in several years or really had to budget or work OT or extra jobs if you are self employed to swing a brand new sled. In the world of problems this is definitely a first world problem but I know it has to feel sheety to have it happen.
Hope the repair, replacement, recall or whatever Poo does to make it right is as painless and trouble free as is humanly possible.

 

[Devilmanak]

To all you guys with new 850s that have blown up I feel for you. That’s really got to be a gut punch, especially if you are a 1 sled guy, only buy new once in several years or really had to budget or work OT or extra jobs if you are self employed to swing a brand new sled. In the world of problems this is definitely a first world problem but I know it has to feel sheety to have it happen.
Hope the repair, replacement, recall or whatever Poo does to make it right is as painless and trouble free as is humanly possible.

That is probably one of the most constructive posts on this thread.
It sucks, but Polaris guys (that I know) love the things so much that they will not jump ship. They just know, and admit, that they need backup sleds. Both the guys I am talking about have their 850 sleds, as well as their old 800 sleds, and their wives' 800 sleds just in case.
As a Doo guy, I will always have a backup also. At least one. I remember in 2015 I had three new sleds in the shop and nothing to ride, they were all waiting on shocks or something.
I hope Poo and Doo get their sheet together, Cat is coming back, the Alpha is legit from my short ride on one.

 

[turboless terry]

I have one friend that locked his up in 50 miles. I thought he had it bad until I stopped at a buddies doo dealership and he is short 30 sleds. A bunch are snow check sleds. At least Coulter got to put 50 miles on his. Hopefully they remedy it quickly.

 

[2XM3]

In our group we all ride Polaris, since the triples and before, new sleds every few years,we all work/have worked in the race engine world, we all can work on them ourselves and we all can pull the engines apart and rebuild them. If there is one thing we have learned dealing with Polaris is never to buy a first year motor from them, period zero exceptions.( probably other manufactures as well) I really feel horrible for guys who have issues with their new sled, hopefully they get it resolved quickly and replace the motors asap.

 

[Mafesto]

To all you guys with new 850s that have blown up I feel for you. That’s really got to be a gut punch, especially if you are a 1 sled guy, only buy new once in several years or really had to budget or work OT or extra jobs if you are self employed to swing a brand new sled. In the world of problems this is definitely a first world problem but I know it has to feel sheety to have it happen.
Hope the repair, replacement, recall or whatever Poo does to make it right is as painless and trouble free as is humanly possible.

Nice post.
We're at nearly 500 posts, and nobody has come on here making fun at other's expense.
That's amazing.

 

[indydan]

Our shop Christmas party, we had a guest with inside info

No kidding!

Thats why I have my stable of sleds... old iron pull the rope and rip! Still faster than anything new on the snow and since im not chris burandt (like so many think they are nowadays) ill just stick to what I always tell people:

"what I lack in talent I just try to makeup in horsepower"

Glad to see this thread calm down a bit but also sad to see this thread calm down a bit!

More really interesting info to come on the 850 bottom end.

I can't get into it until after our Christmas company is gone.


Dan

 

[indydan]

Great question

This has been the best thread in a long time.
Impressed with how quickly Dan identified problem and implemented a fix. (Implementing fixes this quickly is truly the difficult part)

Question to you Dan,
If you observed this engine being assembled at Polaris, would you have been able to foresee these issues?
If so, this is the kind of consultation that would have paid off in spades had they invested in it.

As mentioned several times, hand built prototypes will often times not expose vulnerabilities of production units.
Engineers are smart, very smart. But few have the real world experience to predict how things will react different than numbers and equations.

The answer is yes.

And this has been the buzz at our shop when we took the first one apart.

2 months ago.......( We said the floating PTO bearing was a death sentence during the assembly process. )

And I could not understand how this type set up was possible with no PTO bearing positioning implemented into that bearing.

Chances are the bearing can move under heavy loads even if positioned correctly in assembly......

No locker is REALY risky.

I knew our shop sleds would have to be torn down and the PTO bearing had to be locked...... Or it would forever haunt me in the back of my head.

To date .....I have never seen a floating PTO bearing on a crankshaft that didn't either have a lock ring or a locating pin.

I could not mentally be able to take the sled on a long trip and believe in it until it had locating element put in place.

Dan

 

[snowmobiler]

crankcase compression might be blowing oil lines off.

 

[ADDIE]

Didn't the 2001-2005 Cat 800 and 900 Twins utilize a floating bearing? But I recall they has a locating pin as well?

 

[greasemonkey3406]

Nice post.
We're at nearly 500 posts, and nobody has come on here making fun at other's expense.
That's amazing.

Only one has from what I have read. Just spewing his usual cat piss.

 

[Killer Time Racing]

Didn't the 2001-2005 Cat 800 and 900 Twins utilize a floating bearing? But I recall they has a locating pin as well?

Please stay on topic Kelsey !!

 

[revrider07]

If this floating crank bearing was this bad. Why didn't it show up in the preproduction motors that were running around last year. Some guys ran the 850 for a full season last year under cover?

 

[cascadesnowjunky]

And why has the floating bearing not been detramental on the previous polaris engines. I have a hard time believing if the cases are machined with the correct amount of crush that the bearing will move. I believe it would be easy to install wrong without having some sort of locating pin or retaining ring. This has been one of the most informative threads to date but trying to use the information to form my own theory and like stated above I don't believe the bearing could move if all the machining is correct.

 

[willjogervais]

Originally Posted by ADDIE View Post
Didn't the 2001-2005 Cat 800 and 900 Twins utilize a floating bearing? But I recall they has a locating pin as well?

Please stay on topic Kelsey !!

KTR, How is this not EXACTLY on topic????? Just because Addie said it??

 

[willjogervais]

crankcase compression might be blowing oil lines off.

for this to happen, would it be due to excessive blow by? Or is that what you think is causing it?