Polaris Top End Rebuild Part 2: Remove Cylinder Head & Valve Stems | Partzilla.com
Polaris Top End Rebuild Part 2: Remove Cylinder Head & Valve Stems | Partzilla.com

Hello, John Talley here with partzilla.com.
Today we’re going to be working on our 2011 Polaris Sportsman 850. AS you can tell, we’ve
already been working on it a little bit. What we’re going to do today now that we’ve got
the engine out and somewhat cleaned up, we’re going to star pulling it down to see what’s
going on inside of this. What was it doing? Well, it was still running,
but it had low compression, especially on one of the cylinders. Beyond that, it seemed
to be pushing up a lot of oil through the breather system you know, into the airbox.
Something is going on in there. I’m not sure what, but it’ll probably be in the piston
and rings, but we’re going to start breaking it apart and see what’s what.
So let’s get started. Alright guys, let’s go over some of the tools
you’re going to need for the head inspection project.
One of the most important ones is a 14mm. It needs to be pretty healthy and it also
needs to be a 12-point. That’s going to be used to pull your head bolts.
Other than that it’s just going to be your standard 3/8th sockets, a few different drives.
At least will need an 8, 10, and 12mm. And if you don’t already have a full set of Allens
you’re going to need that as well, starting off with two and going up to 10. I think we
only used a couple of them on this project. As always, you’re going to need your little
hammer, a screwdriver, a pick tool, magnet, and then a couple of mark-sol pens so you
can keep up with where the valves are inside the head.
Beyond that the only specialty tool you’re going to need is a valve spring compressor.
It really doesn’t matter which manufacturer you want to go with. You just want to make
sure that this area here is not bigger around than the actual top of the valve spring holder.
Alright, so let’s get started on this. The first thing that needs to come off is the
valve cover. It’s held on by six 8mm bolts. So let’s go ahead and get those out.
As I’ve said before, I like these little impact drivers, but they’re great for taking things
apart but I do not recommend them to use when you’re putting it back together because you’re
putting it back together because you’re probably going to strip it out, so Just be careful
with these things when you use them. Alright, interesting little note here. See
that? That kind of milky white substance up in there? That tells me that this oil may
have been contaminated with water at some point in time. That’s what that indicates.
This is also a little bit scary. See that bolt right there? That is hand tight.
It’s kind of like doing an expedition: you never know what you’re going to find inside
one of these machines when you start tearing it apart.
Alright guys, what we want to do here is go ahead and bring around the cam shaft to top
dead center. What we’re going to be looking for is a little protrusion that’s going to
come up vertical. Then we’re going to turn it another 60 degrees and that will relieve
the tension on the rocker box. Alright, so it’s come past the vertical, and
then there’s a mark right here that should be even with the head itself.
Alright, at this point we don’t have any tension on the rocker box, but what we do need to
do next is go ahead and pull the tensioner on the cam chain itself.
Once we get that, that will loosen up the tension on the sprocket and the chain. We
can go ahead and remove our rocker box and get our chain off the sprocket.
You want to notice, on the tensioner, it’s actually directional. It has a little stamp
that says “top.” I don’t think it’s possible to actually install
it incorrectly, but they’re just making sure. Just a couple of 8mm bolts.
There we go. Alright. Let’s go ahead and get those rocker
box bolts out now. Alright, everything is looking pretty good
in here. I still don’t like the fact that there’s so much of that milky colored oil
in here. Maybe whatever caused that will come to light as we go along.
I don’t see any abnormal wear so far, which is a good thing.
Alright, let’s go ahead and get that cam shaft bolt out so we can get this chain off.
Alright, at this point if you were not going to pull the head off, which I am, I would
suggest putting a wire on this chain to hold it up. But since I know I’m going further
down into the engine, I’m just going to go ahead and let it drop.
Next, we neet to pull the six main head bolts up top, and then you’ve got two 8mms over
here. Don’t forget about those. And then she should just lift off.
Alright, before I start pulling this apart, like I said, you want to get those two 8mms
out of the way. And there’s a pattern that you need to follow up here.You’re going to
do these about an eighth inch of a turn on each one and the pattern is six, five, four,
three, two, one. You just want to keep repeating that until
all of the bolts are completely loose. This is a 14mm socket that you’re going to
need. You need to make sure that it has 12 point because a regular six point isn’t going
to work. So a 12-point on there. It takes a fair amount
of torque to get these things going so you may have to have somebody help you hold the
engine with a breaker bar to get these things started.
Alright guys, we got everything loosened up and backed out. Boy wasn’t that fun?
I know that tightening these things down you take them to like 43.5 lbs and then you put
another 90 degrees on it. Where does that end up? My best guess is probably at least
100 ft-lbs and it sure felt it when we were pulling this thing apart. It took three of
us to hold it down. So good luck with that. Alright, go ahead and get these 8mms out of
the way, remove all of these. I’m about to forget something. Don’t forget
to disconnect this little hose on the backside that goes up to the thermostat. Just like
that. Off she comes.
Alright guys, here’s what I’m seeing so far: nothing really out of whack on the heads.
A fairly good burn pattern, a little bit of carbon buildup, nothing that extreme. I do
want to go ahead and pull the valves out, take a look at the seats, see if they’re seated
properly. What we want to do is go ahead and number
all of the valves. That way, if we decide to reuse them– which I’m 99 percent sure
we will be– they go back in the same place. That way we don’t have to recut seats or anything
like that. So you want to get a mark-sol or a Sharpie
that is not black. I’m using a silver one here. So go ahead and get those marked.
Set it up in there where your valve is sitting directly down on this point. This little cup
will hold it in place. Reach in there with a little magnet. Pow.
Out comes that keeper. What I’m doing now is just pulling the valve
in a little bit to see how much play there is in there.
Honestly, that feels perfect. Nice and smooth, hardly any play at all and that seal at the
very top still feels like its pliable. Looking at the valve I don’t see any score
marks. Extremely smooth. I don’t feel any lips, any edges right here. You know the valve’s
moving in and out on the valve guide itself and if it were really worn you’d feel a lip
or an edge in one of those two spots and it’s nice and smooth all the way across.
Next thing we’re looking at is the actual seat of the valve or the valve face. You can
see where it’s riding in the seat of the head. I don’t see anywhere where it’s you know,
blowing past it so I’m betting these are sealed up pretty well. I don’t feel any edge on there.
Same story on the valve seat. See that edge all the way around or that circle all the
way around is even. There’s no carbon or buildup or anything that I can see to where it was
not sealed up properly. So this head is in good shape, just judging by this one valve.
I’m not being lazy here, but if this looks this good, chances are the rest of them are
going to look just like that. I mean that was an exhaust– or an intake
valve that I just pulled. We’ll pull just one of the exhaust just for fun. Jump over
to the other cylinder, take a look at it. If it looks that good, I’m just going to put
it back together and I think she’ll be good to go.
The exhaust is telling the same story. And as we saw on the intake side.
A little carbon buildup, nothing that dramatic. The seat looks even all the way around, no
funny wear or marks anywhere. So, this head looks to be in good shape.
So what I’m going to do is put those valves back in and then get back up to the engine
and stat pulling it apart. Alright guys, well the valve’s back in. This
one is pretty much ready to go. I’m just going to go back and clean it up a little bit more
and it will be ready to go back on the engine. I’ll get some of this residual sludge. There
isn’t a whole lot of it in there but I want to get it back clean before we put it back
on the engine. Listen, this part of the diagnosis of the
engine is complete, so this piece is ready to go back. What we are going to do is go
further into the engine so that means we’re going to split it in half, take a look at
those pistons and rings, and the cylinder bore and see how that looks.
So you need to come back and follow up on our next video and find out what’s really
going on with this machine. Listen, we appreciate you watching and we’ll
see you in the next video. Thanks.

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