[Tlmunn]

I noticed before one ride I was down almost a quart of oil.I saw no leaks and filled it.I went for a couple rides over the next few months and I checked the oil and it was down almost another quart.
I ran it by the dealer and he said it had to be leaking or if driven in dusty conditions then maybe the rings were worn due to dusty air getting by the air filter.
On the pto side I had a intake boot leaking as detected by spraying brake clean around that area.
I did notice below the boot on the Mag was wet prior to doing any test with the break cleaner but it did not seam to leak or try to shut off when applying the brake cleaner the way the pto side would shut off when the cleaner was applied.

I did a compression test and had 180 on the pto side dry and 210 wet.
" " 165 on the mag side dry and 180 wet.
I did a leak down test and had 25 % loss on pto side.
" " 65 % loss on the mag side.
I could hear most of the leakage out the filler cap and dipstick hole .I repeated the leak down test on the bench once I removed the motor. The leak down results were similar and I could hear some leakage out the intake valves and if I put some brake cleaner in on top of the valves from the intake I could see it bubbling from the air being applied to the tester/ cylinder .Leak downs were done at TDC.
I know for sure it was leaking around one boot but ironically that side has the best numbers.I could not see any bubbles in the rad when i did the tests in while the motor was in the bike nor hear any air coming from the water fitting on the block or coming out the water hose nipple on the water pump when I repeated the leakdown test on the bench.
I have an idea whet is going on but wanted to see what you folks had to say about my numbers.

 

[pyromedic]

The first thing I would do is adjust the valves and re check the leakage. if leakage is still high it's probably time for a top end.

 

[Tlmunn]

The first thing I would do is adjust the valves and re check the leakage. if leakage is still high it's probably time for a top end.

I have never adjusted them before and have seen a video on you tube how they did the 900 rzr motor however would this be a reasonable test?? What if I checked what they call the buckets and make sure they are not touching the cam lobes thus not pushing on the end of the stem thus not holding valve open.
I will also add that there was not air heard in the tailpipe while performing in bike however when you can get your ear right down next to the exh port you can hear a little bit and see the brake cleaner bubble when the air is applied to cylinder while piston is tdc compression.

 

[Jungleman]

T, with that kind of leak down....it is rings and scored cylinders.. Better get Nflow.. it does not take long with a TB adapter cracked in dusty conditions to do the damage.

 

[Tlmunn]

T, with that kind of leak down....it is rings and scored cylinders.. Better get Nflow.. it does not take long with a TB adapter cracked in dusty conditions to do the damage.

I went out to the garage and checked to see if i could get my smallest feeler gauge in between the bucket and the lobes on the intake cam while i had the pto side on tdc comp.stroke.I could fit it in between so i know there is atleast some clearance.Would this tell me the intake valves for that cylinder are in the fully closed position

 

[Jungleman]

Yes.................

 

[Tlmunn]

I tried the feeler .0015 /.0.04 mm gauge under the cam lobes while the mag side was at TDC and it would not fit.I could rotate the buckets with a small piece of wood so there was very little pressure from the cam on them but the feeler gauge would not pass between the bucket and lobe.

 

[Jungleman]

Then I would get them adjusted as Steve said and then recheck.

 

[Tlmunn]

Then I would get them adjusted as Steve said and then recheck.

Could I get that mag side up to tdc compression then take the cam holding bracket off or back it off so there is clearance between buckets and cam lobes and then do the leak down test on that one again.

 

[pyromedic]

Yes, you could put any given cylinder at TDC, remove the cams and perform a leak down test to prove that the valves were not the cause of high leakage - with the caveat that if a valve or seat is burned it will leak no matter what.

You could also completely remove the cams and check each cylinder at TDC. If I was going to do that I would check clearances at all buckets before hand so I could purchase the correct ones to attain proper clearance if the leakage happens to only be due to tight valve clearances. Doing so will save the step of reinstalling the cams to check clearances in order to determine the proper replacement bucket requirements should the cylinders check out OK and a complete top end job be unnecessary.

A valve, even slightly lifted from it's seat or burned will leak quite a bit, enough to have higher than normal cylinder leakage. It's also possible for carbon to get between a valve and it's seat, hold it off the seat and cause some leakage. I don't think that is a likely scenario with a fuel injected engine unless it's also been consuming oil at a high rate or has spent long periods at low RPM and or idling.

Once valve clearance issues are eliminated either by proper adjustment or removal of cams, if leakage is still high you can determine whether burned valves or rings are the cause by putting a tablespoon or so of 30 or 40 wt engine oil in the cylinder through the spark plug hole, rotating the crankshaft a couple of turns to disperse the oil to the cylinder walls and performing the leak down test again. If there is a significant decrease in leakage the problem is rings.

Jungleman is suspicious that the leak at the intake boot has caused high cylinder leakage because it has occurred in so many cases previously. On the other hand, you may be lucky if your driving has been almost entirely in a clean environment such as driving on paved roads 99% of the time, not riding on or following other rides on dusty trails. Theoretically, an engine run in a clean atmosphere would not receive damage to the cylinders even with leaking intake boots because there would be no dust or abrasives to get in. Granted, that is not the usual case for most owners, but if you happen to be one of the few who drive in mostly clean conditions you may be lucky and the problem is only valve clearances.

 

[Tlmunn]

I tried the oil trick during my compression test while the engine was in the bike however the motor leans backwards so I was concerned I was not able to get enough oil to the exhaust side of the piston and rings I would say I used maybe 4 tablespoons full of oil and then rechecked the compression. Those are the values above where it says wet.
The motor is out and on the bench so i can get the pistons level .It was tricky to get the pto side piston not to turn when the air is applied so I reinstalled the clutch and bolt and held it in place using a powerbar on the clutch bolt while a helper hooked up the air to the test gauges.It could be tricky with the no gears to hold the chain out of the way but ill see what i can do.

I might also say that the reason for all the checks is oil going down in the engine and oil in the hose from crankcase to breather and in the breather and the hoses from breather to intake.I never saw any leaks on the ground or saw any signs of burning oil like smoke but have read that the synthetic oil does not smoke like the non synthetic oils so it could have been burning a little at a time and never even noticed it.I am guilty of not checking the oil enough and now im paying for it..
Also I had been out on several solo rides and came back and the bike was very dusty and the contents of the dump box behind where we sit was very dusty so i have definatly ridden on dusty roads and with that boot bad I noticed some grit in the tb boots and the plastic box behind it.Its too bad the rings and or cylinders is so hard to replace without taking the bottom apart.

 

[Tlmunn]

I redid the leak down test with the cams removed and was getting air past the valves and coming from the dipstick as well as the cam chain area.
I also had an issue when I removed the cam chain tensioner the chain jumped on the gear while i tried to rotate the pistons with the clutch and my timing got out of wack.
I was not too worried about loosing timing because i was removing the head anyway .It needs some work due to the poor seal around the valves.The had was full of carbon .I will clean it up and maybe see if the engine shop could service it for me and see what the cost would be.
I will try and attach some pics of the cylinders.

 

[Tlmunn]

It "looks like " there is a lip or an edge on the cylinder wall where arox. around the top ring would stop.I'm wondering if the rings wore enough material of the wall on that side to cause blowby down to crankcase.

 

[BPS]

That wear at the top of the cylinder seems to be common on Polaris engines. When a leak down test shows cylinder blow by I almost always see that wear pattern. My opinion is you're going to need a new cylinder.

 

[Tlmunn]

That wear at the top of the cylinder seems to be common on Polaris engines. When a leak down test shows cylinder blow by I almost always see that wear pattern. My opinion is you're going to need a new cylinder.

Thank you.Do you mean common and the cause for air coming from the dipstick and filler cap ??
Its hard to tell but do the cylinders seem very polished to you.The are very smooth and shiny to me.

 

[BPS]

By common I mean that I see it a lot on Polaris engines that I tear into vs other manufacturers cylinders. Yes, it seems to be the cause of oil burning and air coming from the crankcase when doing a leak down test.

I believe Polaris cylinders are Nikasil coated and the off colored area is where the rings have worn through that coating. Someone correct me if I'm wrong.

 

[Tlmunn]

By common I mean that I see it a lot on Polaris engines that I tear into vs other manufacturers cylinders. Yes, it seems to be the cause of oil burning and air coming from the crankcase when doing a leak down test.

I believe Polaris cylinders are Nikasil coated and the off colored area is where the rings have worn through that coating. Someone correct me if I'm wrong.

I believe this cylinder is nikasil coated and that is the aluminum under the coating.I see a ridge in that area too which i can easily catch with my fingernail.I would think that the coating would be right to the top of the cylinder and not be a ridge there would you agree ?

 

[BPS]

Yes, there should not be a ridge. The ridge location most likely coincides with the stopping point of the upper piston ring at TDC.

 

[Tlmunn]

Yes, there should not be a ridge. The ridge location most likely coincides with the stopping point of the upper piston ring at TDC.

That is what I think as well and the ridge was the original material and below the ridge was from ring wear possibly accelerated by dust inhalation.

 

[Tlmunn]

You could also completely remove the cams and check each cylinder at TDC. If I was going to do that I would check clearances at all buckets before hand so I could purchase the correct ones to attain proper clearance if the leakage happens to only be due to tight valve clearances. Doing so will save the step of reinstalling the cams to check clearances in order to determine the proper replacement bucket requirements should the cylinders check out OK and a complete top end job be unnecessary.

I got my clearances before i removed the cams and then i double checked them on the bench as well and they were the same numbers.two intakes had no clearance at all.
I will have to get someone to help me figure out which buckets I will need.