Need Help!! Sled Fouling Plugs

TUFFPOLARIS · Feb 6, 2015

Need help!! Got a trip planned leaving on Sunday (12h drive). My 2014 800 RMK is fouling both plugs about every 5 miles, a couple times it was less then that. Gone through 4 or 5 sets already. The sled only has 600 miles and about 50 miles this season. A couple times it first fouled one side, then very shortly after the other side as well. Twice when I let it idle for a while after driving a couple miles the sled just completely died almost like you would hit the kill switch. Change the plugs and it runs perfectly again for another couple miles.

Just installed a MTNTK full mod and it started after that but im not sure that is the problem. Ran a data log with the bullydog and MTNTK said everything looks good as far as the mapping is concerned. TPS is good, settings are within spec and no spike in voltage in any throttle position. Both spark plug caps and wires looked good so trimmed the wires and reinstalled caps. What could be causing this? I desperately want to get it going today or tomorrow in time for our trip!!

xc6rider · Feb 6, 2015

Running extra oil for breaking in new top end? All 50 miles this season on the new top end? Checked compression? What you running for fuel?

Seen lots of injector problems on 14's. Have you checked pressure, and see if it holds?

Just a couple things to think about... Seems like youve checked your coils primary/secondary and caps etc.

TUFFPOLARIS · Feb 6, 2015

New top end has about 15 miles. Yes running 40:1 premix in tank. Also the tech had to turn up the oil pump 2.5 turns to bring it to Polaris spec. Check valve was installed in oil tank just before new top end as well. Would that combination over oil THAT much? Only burned half a tank of gas so tough to say how much oil it has used.

xc6rider · Feb 6, 2015

Very well could be. Did he turn it up 2.5 turns to align the oil pump timing marks, or did he just turn it up that much and tell you that?

Why the new top end at 600 miles?
Did you ever determine your oil consumption/ratio prior to the new top end or the tech turning up the oiler?
What do the fouled plugs look like?

2.5 turns on oil pump is a BIG gain from what it would of been running before, and unless he knew the ratio it was running before hand, he shouldnt have touched it! Coupled with 40:1 in tank, and the new check valve, id bet your running a ton of oil.

You need to run it tho now, to determine what ratio it is running. If i did the work, and KNOW i adjusted 2.5 turns, id reverse it. But, without knowing for sure, you may burn it up...

xc6rider · Feb 6, 2015

First thing i would do if i were working on it, is visually inspect the oil pump/arm timing marks and verify its all installed properly. Adjust them according to the manual (supposedly what the tech did). Id double, tripple check that and get it set there. Continue running premix in tank til you can measure and determine how much oil/what ratio your pump is running. Then and only then, make adjustments to the oil pump to get it where your comfortable.

He could of had the oil linkage apart and reinstalled improperly, causing the pump to run full flow. Was the whole engine pulled for the new top end?

xc6rider · Feb 6, 2015

http://www.snowest.com/forum/showpost.php?p=3794277&postcount=12

Check out that post, it has a pic out of the manual for setting the oil pump timing marks. Thats what you need to look for. Pain in @ss, youll prob need to remove silencer and use some mirrors to attempt inspecting the marks. Pump is hidden underneath the throttle bodies way low! Sometimes its even easier removing seat, fuel tank, airbox etc just to get a good look!

TUFFPOLARIS · Feb 6, 2015

Thanks for the replies. Reason for doing the top end is sled was low on compression on one side. Sled was still running but one piston was slightly scored. Ran perfect all of last year, started having issues the first ride this season. I think it had something to do summer storage but that's just my theory.

The motor was completely removed from the sled, but just the top end was done, crank/crankcase were not touched. The tech showed me the oil pump timing marks before he adjusted it, and after as well. I was not there when he did it but he said it was 2.5 turns.

I checked a couple times last year and the average oil usage was 55:1. 205L gas to 3.750L oil. I just calculated how much oil the sled has used now since the top end rebuild. I filled in 325ml oil and the gas tank is showing exactly half a tank. Now assuming the sled has used 20L of gas, and taking into account the 40:1 premix in the tank (another 500ml for the 20L of gas), im running just over 24:1. Ya I guess that could foul a lot of plugs. Oh ya the sled is running premium gas on the ethanol setting.

TUFFPOLARIS · Feb 7, 2015

I drained the gas tank and refilled with fresh premium gas premixed 70:1. Went for a 6 mile ride and still the same thing.

After keeping it around 4000-6000 rpm for a little while I could feel the plugs starting to foul. It would sputter and bog at WOT after driving at those lower rpms for a bit. It would eventually clear up after being on and off the throttle for a bit at 7000-8000 rpms. The bogging got worse and worse the longer I drove and it finally got to the point where it bogged at WOT no matter how much I feathered the throttle. I stopped and let it idle for about 30s to a minute and one side completely stopped working and it only was running on one cylinder. Not sure what to do. Maybe turn the oil pump back down? I hate to be cutting back on oil while breaking in the new engine.

LoudHandle · Feb 7, 2015

There are plenty of posts on here and other forums where the oil usage nearly doubles when either venting the tank / cap or replacing the stock Kelch made cap with the Paaso cap or the newer Skidoo cap. If you did both and turned up the pump you are most certainly over oiling the engine now. Especially when you compound that with the additional premix in as well, it becomes a near certainty.

Most owners are finding that when they finally change out the problematic stock oil cap, they have had to go back to the stock oil setting or very near it. To avoid the issues you are currently dealing with. FWIW in my experience

Old Scud-doo · Feb 7, 2015

MtnTek fix kit. Ski-doo cap. 1.5 turns extra on cap, 2 ounces per gallon added to tank. First 70 miles yesterday with no problems. Maybe I am lucky. Hope so, it's about freaking time!

wfieldin · Feb 7, 2015

Is your antifreeze level staying good? Head oring pinched? Did you put stock reeds back in or something else?

NapaMatt · Feb 7, 2015

Over Oiling !!

Merlin · Feb 7, 2015

NapaMatt said:
Over Oiling !!

Ditto!

As others have mentioned venting the tank, albeit a good thing, has exacerbated your situation.

Since you've confirmed the injection pump is working, there is no need to run any pre-mix. To add, pre-mix is of negligible benifit to the engine anyway due to the placement of the injectors.

You could also try running the NGK Iridium spark plugs. Some have claimed reduced fouling with these....

Good luck!

CO Powder · Feb 7, 2015

TUFFPOLARIS said:
New top end has about 15 miles. Yes running 40:1 premix in tank. Also the tech had to turn up the oil pump 2.5 turns to bring it to Polaris spec. Check valve was installed in oil tank just before new top end as well. Would that combination over oil THAT much? Only burned half a tank of gas so tough to say how much oil it has used.

I suspect over oiling as well. If you have burned 5 gallons of gas you can certainly do the math for a ballpark ratio. I think your listed changes have you under 20:1 where performance will suffer.

TUFFPOLARIS · Feb 7, 2015

Antifreeze dropped a little bit after my first ride but that's normal after doing a top end. I topped it off and has been good since. Stock reeds without the stuffer blocks as per MTNTK recommendation. Going to turn oil down back to where it was before doing the top end and see if that makes any difference.

geo · Feb 7, 2015

You should be able to see an oil fouled plug right away. It'll be dripping with oil. Enough to bridge the plug gap if you turn it right side up or there will be a bridge of carbon in the gap. Fuel fouling is different and the plug comes out black with no obvious bridging of the plug gap. It simply got too cool from fuel.
Personally, I've been running 24 to 1 on heavy days for 3300 miles and never fouled a plug. I use the EYA NGK plugs and a step hotter (8 EYA) so I can over fuel abit. I've found them to be more resistant to fuel fouling than the fine wire standard plugs since they came out in the always rich Suzuki motors. Never gap more than .26.
But, I don't know if any of this is your problem or not.

Just to throw something else in the mix, I know of another sled that has the exact same scenario as you after just a top end change. Same rpm, same fouling issue for a few tanks of fuel earlier in the season and many sets of plugs including iridium.
Difference is no oiling changes made, throttle bodies not disturbed.
Unfortunately our phone conversations stopped because he had to stop riding and I don't have an answer.
I chimed in because I thought it was quite coincidental for the same plug fouling scenarios with two different packages right after reassembly.

Have you phoned MNTKT?

TUFFPOLARIS · Feb 8, 2015

Turned down the pump to where it was before. Made no difference. Changed the tps even though it didn't look like that was the issue. No difference. According to what your saying the plugs look more like fuel fouling then oil fouling. They are very wet and black.

I called mtntk when this started. Did the data log and they claimed that the map was good. He suggested maybe tps, spark plug caps or wires. Also he mentioned that my tps was never at 100% throttle. Max was 95-97%. That's why he thought it could be the tps.

Heading west right now. Gonna try it at elevation. At home where I was having issues I'm at 1100ft. Gonna be riding 5-8k which is exactly where mtntk does lots of testing. Taking a spare sled just in case.

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TUFFPOLARIS · Feb 8, 2015

I did try iridium plugs and they did last a bit longer but still the same issue

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xc6rider · Feb 8, 2015

Did you check fuel pressure for open injectors?

LoudHandle · Feb 8, 2015

If it is over fueling, I see two (probably more) possibilities. First fuel pressure is too high allowing the injector to flow more than anticipated per injector opening. Or a hanging injector (open longer than it should). To my knowledge the ECU is a "dumb System" with no feedback of what is actually happening fedback to the ECU.

Need Help!! Sled Fouling Plugs

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