2012 pro 800 bog/misfire/dropping cylinder??

[907assault]

I searched and searched through the forum and could not find a description or issue that sounded like mine.

2012 pro 800 / 960 miles / bone stock with some clutching. I turned up the oil pump, add 1 oz of poo blue per gallon of fuel. Recently installed BRP xps oil tank cap.

At intermittent rpm and temps, engine bogs down like it literally fouled a plug, HARD, for a few seconds, then comes back alive. Then repeats. sometimes plugs look wet and oily, sometimes they look perfect. When it bogs out, it is definitely running on one cylinder.

Where would you guys start digging with your knowledge and experience on these engines? Any help will be appreciated.

 

[Gotmud]

Compression check is in order. My 2011 started dropping a cylinder at the oddest times and then come back, I didn't think it was the engine because it ran so damn good when on 2 cylinders. The compression was 5psi off, just enough to cause problems. I chased the dropping cylinder for 2 seasons lol, ran awesome this year.

 

[Old Scud-doo]

That is the dreaded piston and rings. How many miles on them? I will get flamed I am sure but I had somebody from a very large aftermarket company tell me they only get about 1000 miles on their Pro 800 motors before they have to rebuild them. Same problems or similar. I had flaking pitted rings with knifing pistons. Some people have zero issues but there is a reason there is a "fix" kit for the Pro 800 motor. Mtn Tek makes a good one if you need it. I would put my money on pistons and rings since I tried everything else when that was happening to me. Tried blaming injectors, then reeds, tried some other stuff too. Finally had it tore apart to find it was exactly as I was told it would be. So...Good luck!

 

[907assault]

The inconsistency is what's odd. On again / off again. Just like you said, runs like a raped ape, then falls on its face / one cylinder for a few seconds, then comes back from the dead. Inconsistency in plug condition as well. Could this be the rings rotating, creating the inconsistent sealing? Is that possible?

The only thing I can contribute to when this started happening was installing the BRP oil tank cap. Could be coincidence I guess.

For example, every time the sled would start coming and going with the bog, I would pull the plugs and they would be wet with fuel/oil. I would change them, and it would run great for awhile, then start it again. Then yesterday, on a deep day, it started bogging much more frequently. I stopped and pulled the plugs, they looked pretty damn good. Not wet with a mid brown burn. I replaced them anyways, started it up, bog city.

Oh, engine is all original / 960 miles.

 

[Turboegt]

Sounds like you may have turned the oil up a little too much.

 

[907assault]

I've thought about the oil being turned up too much as well.....maybe loading a cylinder up, then it comes back and burns it up?

I just got done removing my muffler, pipe, and y-pipe. Cylinders still have the cross hatching (very visible), Pistons appear in great shape, and I can't see any discrepancies with the rings.

I will post some pics later to get you fellers opinions.

 

[The Bob]

Compression test says?

 

[diamonddave]

I've thought about the oil being turned up too much as well.....maybe loading a cylinder up, then it comes back and burns it up?

I just got done removing my muffler, pipe, and y-pipe. Cylinders still have the cross hatching (very visible), Pistons appear in great shape, and I can't see any discrepancies with the rings.

I will post some pics later to get you fellers opinions.

Turning up the oiler, running 1 oz per gal in the tank, AND running a different oil cap (BRP) will increase oil usage to the point of fouling plugs.

Install some new plugs, lower your added oil to 1/2 oz per gal, mark your oil tank with a marker, bring some extra plugs with you and go for a long ride and measure your oil consumption.

 

[Reg2view]

Had this happen on an 11 after a dropin kit and high compression head, intermittingly oil fouling a plug. If you're seeing oil on the plugs, it's too rich.


If you put in fresh plugs, and it doesn't do it the rest of the day, you found it. Then either back your oiler off a half turn, or reduce the premix as stated by diamonddave. Could be a simple fix.

 

[Old Scud-doo]

That would be great if it's just too much oil. I would foul plugs left and right. Put in a new set and run awesome for a bit then drop a cylinder. Did all things you say yours is doing. Hope that it's as easy as a fix and these guys believe it might be. Please post if it is.

 

[907assault]

 

[907assault]

Vertical bright lines are camera flash induced

 

[907assault]

 

[907assault]

 

[Sage Crusher]

Looks like a bunch of oil on there-
I would reduce the oil in the tank as DD stated and run it and see-
Since your in there check the compression and provide feedback.....
Also the Power valves need a good cleaning after that many miles

S/C

 

[907assault]

Yes, I will perform a compression check. I cleaned the exhaust valves at around 450 miles. Probably due again anyways as you say since there has been lots of oil to goop up. I will be out of pocket for about a week. When I return home, I will continue on with the investigation. Thanks for the help boys. Any other ideas that you can come up with will be greatly appreciated.

 

[Old Scud-doo]

What plug you running? I ran the Iridium IEX version. Really hard to foul. Might not be a bad option either.

 

[907assault]

Running the OEM plugs. What is the part number for the iridium plugs?

 

[icr]

Could be an injector

 

[907assault]

I've read on here there's a place to send an injector harness with injectors for testing, if I remember right. Not sure.


Almost seems like I could just remove them and check for blockage, or does it need to get more precise than that? Flow and pressure measurements, etc?