Blew a spark plug out. Thoughts?

[CantwellAxys]

Hello everybody, been lurking for awhile, first reason to post:

2016 RMK 800 with an SLP pipe, can, and clutch kit. 1600 miles on the sled, 250 miles since the SLP install.

Ride before last I got the detonation code twice, both times at full throttle crossing a wide open area. Have never had detonation previously and hoped it was just bad gas.

Before the next ride I siphoned the gas out and started with fresh gas from a different station. Halfway through the day I developed a bad bog in the mid range, stopped to check plugs, and they were both super loose.

Put in new plugs, made sure they were tight, rode for about thirty minutes and blew my clutch side plug out of the head. The other plug was already loose again as well.

Put another new plug in to the clutch side, tightened the other one, made it 5 minutes and blew the clutch side out again. At that point there was only about a thread and a half left in the head, but was able to get plug in enough to stay in while I limped back to the truck.

Any thoughts on why my plugs would be loosening? I've done 6000+ miles of riding over the last 6 winters on 5 different machines, I'd like to think I know how to install a spark plug. It's not rocket science lol

 

[DUKHTR3]

It's from detonation. It will rattle your plugs loose. U need more octane.


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[sledhead_24_7]

As mentioned above, detonation. You need more octane, or SLP needs to get you some adjusted fueling. Or you could take it back off.

 

[CantwellAxys]

It's from detonation. It will rattle your plugs loose. U need more octane.


Sent from my E6810 using Tapatalk

If it was detonating bad enough to loosen spark plugs, wouldn't it have thrown the code again? No codes on the last ride.

 

[CantwellAxys]

As mentioned above, detonation. You need more octane, or SLP needs to get you some adjusted fueling. Or you could take it back off.

Been running non-ethanol 91 octane from the same gas station since new, and no detonation til this last ride. 91 is the highest I can get locally (Healy, Alaska).

Does detonation occur more at warmer temps? Last two days were the warmest I've ever ridden it. Probably 30 degrees the first day, and mid 40's the second day. Most of my riding is between -15 and +25 degrees f

 

[Dazzler]

Maybe check/change fuel filter? Or possibly fuel pump pressure low?

 

[CantwellAxys]

I did pull the head off to check pistons, I'm no expert but they looked fine to me. Anybody see any red flags? Photo on left is the clutch side, the one that blew plug out

 

[SRXSRULE]

Like others have said....DET is what blew the plugs out of it. Its easier to see signs of det on the spark plug then the piston in most cases.

If you want to prove its low octane just add 2-3 gallons of 110 race gas to the tank and see if the plugs comes loose. I'm betting they dont.

 

[Wheel House Motorsports]

Been running non-ethanol 91 octane from the same gas station since new, and no detonation til this last ride. 91 is the highest I can get locally (Healy, Alaska).

Does detonation occur more at warmer temps? Last two days were the warmest I've ever ridden it. Probably 30 degrees the first day, and mid 40's the second day. Most of my riding is between -15 and +25 degrees f

Yes, the warmer the air going in the easier it is to detonate.

Ive had numerous sleds that dont knock enough to throw codes but all of a sudden the plugs are loose. You must have just been riding a fine line of super close on things and the added ambient temp is pushing you over the edge.

 

[ak]

Are you running the resistor? And how are you getting 91 octane we only have 90 in Alaska.

 

[CantwellAxys]

Are you running the resistor? And how are you getting 91 octane we only have 90 in Alaska.

Yes, running the resistor, I thought it was 91, maybe it is only 90. I know its not 93 like back home

 

[CantwellAxys]

Yes, the warmer the air going in the easier it is to detonate.

Ive had numerous sleds that dont knock enough to throw codes but all of a sudden the plugs are loose. You must have just been riding a fine line of super close on things and the added ambient temp is pushing you over the edge.

Right on. Got a new head coming, and snow is pretty much done anyway. Sucks to have a problem, but better now than start of next season!

Thanks to everybody for the input

 

[TRS]

Hopefully all that det didn’t hurt your rod bearings. That kind of det is hard on rod bearings.

 

[ak]

I have two friends running a 16 800 axys with slp pipe with resistor on 90 octane, one of them had a spark plug back out. There both still running fine. 1,000 to 1,200 on both sleds.

 

[akpowderhound]

I have two friends running a 16 800 axys with slp pipe with resistor on 90 octane, one of them had a spark plug back out. There both still running fine. 1,000 to 1,200 on both sleds.

I run my Axys with the SLP pipe and Resistor on Chevron 90 fuel up here in AK. Iv seen Det only twice in 1000 miles. If I batch a gallon of Av gas and with any gas station 90 it hasn’t detonated at all.
I have gone through a couple pipe resistors now though. I do believe something is wrong there. SLP won’t stand behind them and charge me for new ones each time.
The 90 fuel in Healy AK is questionable. If have some AV gas on hand to ensure myself I’m feeding the sled enough octane.
Cheap Insurance

 

[AKSnowShredder]

I happened to be searching up Snowest for answers on this problem and sure enough, it has happened to someone else... Was riding yesterday and the clutch side threw the plugs as well. And it messed up the threading on the head so I'm screwed. I've been running 90 (Best we have in AK) for the entire time I've owned my Axys and this is the first time it has happened to me.

 

[akpowderhound]

Once you decided to add the SLP pipe set you amplified the need for good fuel in your Axys.
This is first hand experience from the same area as you are in.
Semi-unique situation as all our fuel is Eth free but lower octane that recommended for the sled with mods.
I am telling you that the 90 off the Healy pump is not in high demand and I’m confident it’s not 90 octane. Batch some Ava gas with it and I’m sure you’ll be fine.
Once you install the new head that is!