Polaris Sportsman Ace 570 Rebuild - Part 2 - Assembly - New top end

If you saw my last video, you would have seen that "Dwight", our 2018 Polaris Sportsman Ace chugged some mud, essentially ruining the top end. We had a clogged throttle body, heavy scoring on the cylinder walls, and damaged piston rings. All the parts are in and today we are going to begin the assembly on the new top end!
Fortunately the top end of the 570 can be done with it still on the frame. If you need to do the bottom end, you'll need to pull the engine and split the case. Had it been run any longer, it could have damaged the rod bearings which would have required a complete tear down. That is why it is essential to shut off the engine at the first sign of trouble, especially when it is in the mud!
After tearing down this engine, I am glad that I went with a new top end. I am sure that I could have cleaned out the throttle body and it would have operated, but it would have been down on compression and burned oil. I also may have been able to get away with honing the cylinder and just replacing the rings, but after looking at the prices it just made more financial sense to me to replace the entire top end. It was roughly $400 for all the parts, which were in stock and I had them in 3 days.
Hopefully you never find yourself in this situation, but if you do this video should help. Everything shown here is per the service manual. This video is for entertainment purposes only, and no part of it should be attempted. Only licensed repair shops or your local dealership should make any repairs on your machine. Working on a machine yourself may void your warranty.

[@jsmith9970]

If you have assembled more then one single cylinder assembly you’d have figured out that and talking the piston and rings into the cylinder then putting the Weinstein pin is a single mechanic job and takes less time Just remember to lay a tag across the block under the piston in case the clip drops.

[@3DayWeekend]

In the Chevy Cruze videos, you'll see that I've rebuilt a 4 cylinder and got a ring compressor tool for that and was able to do it myself, no problem. ATV engines are odd because you slide the cylinder down onto the piston and block, vs a car engine, the cylinder is in place and you lower the piston and rod into the cylinder. I used to struggle with the wrist pin clips as well, but I've gotten pretty good at those through much unwanted experience. Hopefully we are done blowing engines for a while! I'm getting tired of rebuilding them! Thanks for your comments and for watching!

[@alphapackoffroad]

Looking good. I'm currently rebuilding a ranger 570 on my channel. Crank bearing failure from rolling over and being left running.

[@3DayWeekend]

Terrific! Between the two of us I think we have the 570 covered then! I was relieved my crank bearing and rod were OK! Really didn't want to pull the motor entirely!

[@alphapackoffroad]

@@3DayWeekend if you have to it really isn't too bad

[@michaelthechef]

Best tip for the circlips is to buy circlip pliers

[@3DayWeekend]

I was looking for some, but they seem to be size dependent. Didn't know what size I was working with, so we went old school! haha Either I got lucky this time or I'm getting better, because it went in pretty easily this time around.

[@rickcarlson4574]

Where does one find a service manual with the tork specs

[@3DayWeekend]

There are electronic (downloadable PDF) and paper versions of the service manual available on eBay.

[@dondelche]

Great video. I really enjoy these longer repair videos. Will you be making any modifications to try to prevent this issue in the future?

[@3DayWeekend]

Glad you liked it! I had tossed around the idea of a snorkel kit, but I'm not a fan of chopping up the box and body work. I may do a "frog skin" over the intake, but the main difference is if he gets stuck, just stop spinning and get winched out. He probably spun his tires for 3-4 minutes trying to get out which was enough to fill the air filter box completely and get through. Thanks for watching!

[@MartinBargholz]

Remember that when you reuse bolts, they don't stretch as well as new bolts, they probably shouldn't be tightened by 180 degrees and again 180 degrees.

[@3DayWeekend]

Exactly right. After the first 90 they were very tight! You could feel them tightening right up. Thanks for the comment and for watching!

[@shanek6582]

Man I've got the same 570 engine in my 2019 atv and I've just torn it down this far because it was pushing oil into the air filter, clicking really bad on the top end and putting a bunch of air pressure into the bottom end when I checked pulling the oil dipstick when running. I totally assumed it had bad rings or crack in the piston but I can't find a single thing wrong with anything! Piston/rings look good, valves all look great and the springs all have good and even pressure. Could timing cause my issues if it had jumped somehow? I'm desperate lol, thanks for any advice.

[@3DayWeekend]

I'm with you - first thought was piston/rings, but that's usually accompanied with it burning oil out the exhaust and wouldn't explain the top end noise. If your crankcase is pressurized, that would explain the air in intake because it's pushing through the crankcase vent. Timing is easy enough to check - just look for the marks on the crank and cams. Even if it is one tooth off, that's where you should start - chain or tensioner. If it's clicking up top, you could have a bad tensioner or something is wrong with the valves/cams/sprockets. A bad tensioner would allow the timing chain to skip teeth so you might be onto something there. It also might be worth pulling the valves right out of the head and checking them over real good. Is your coolant nice and clean? Perhaps you have a crack in the head or cylinder, but I'm leaning toward the top end.

[@shanek6582]

@@3DayWeekend thanks a million sir. I'm going to look over that head and valves a little better. I ordered the jug/piston kit but I might just put the old ones back on and I'm definitely going to order a hot cams tensioner and put it on. Thanks again!

[@berlnberln5289]

if I understand well you did not lap the valves ? Have you noticed any valve leak since ? Had almost the same misfortune and my valves were pitted by the debris, a leak down test showed leak from my intake and exhaust.

[@3DayWeekend]

You're right, I did not lap the valves. I did the ol' carb cleaner leak test while the head was off and there were no leaks, so I did not lap them. No leaking since, compression is right in the 'normal' range. Engine is running great with no oil consumption. It has probably been 300 miles since the rebuild and it's running great! Thanks for watching, and good luck on your rebuild!

[@michaelsalter5367]

Hi, I’m in the middle of a tear down on our Polaris Ace 570. What parts did you use? I need a new cylinder, piston, rings and gaskets. Thanks

[@3DayWeekend]

I used all OEM parts for this rebuild. You can find them here: www.rockymountainatvmc.com/oem-parts/Polaris