My spark plugs at 66,246 miles

[W0QNX]

I changed my NGK CR9EH-9 out with the same new plugs. These were in the bike the last 66,246 miles. The bike has 364,598 miles total now. It looks like #4 is getting some carbon in there. I also looked down the cylinders with a cheap bore scope type thing. The #4 does have some carbon around the sides of the piston top but not real bad.

Cyl 1 (bike front left) to Cyl 4 (bike rear right) shown from right going left in the pic.

All plugs had in tolerance gaps at about .033 to .035 when removed.



Comments welcome.

 

[Mr.E]

Might be a worn valve seal but I doubt it's making any difference to the oil level, looks pretty good for that mileage!

 

[Al st1100]

If your looking in the cylinder If the edges around the piston are clean the rings are starting to leak. But with the miles on that motor and the looks of those plugs I wouldn't be too concerned . Carbon on pistons is inevitable.

 

[red one]

Mine looks similar to that and I change mine every 24K miles. Yours don't look that bad for the mileage and non iridium plugs.

 

[Igofar]

That’s why I don’t waste money on specialty plugs.
Yours look good because you ride your bike.
Run a couple oz of MMO through your fuel and that will clean up #4.

 

[sky.high]

Don't think I could ever bring myself to run something called Marvel Mystery Oil through my engine. There again Sea Foam doesn't sound like a great idea either LOL

 

[Kevcules]

Did think I could ever bring myself to run something called Marvel Mystery Oil through my engine. There again Sea Foam doesn't sound like a great idea either LOL

My engines (all my internal combustion engines, lawn tractor included ) just love that stuff!

 

[SMSW]

Your bike is just getting broken in....

 

[Igofar]

Did think I could ever bring myself to run something called Marvel Mystery Oil through my engine. There again Sea Foam doesn't sound like a great idea either LOL

Seafoam is a cleaner with a little bit of lubricant, MMO is a lubricant with a little bit of cleaner, they both play well together.
These are two piston's out of matching 2008 Yamaha TW200's that I purchased new.
At Approximately 6,000 miles I replaced the cylinder base gasket(s) (recall) and decided to replace the piston's at that time, just because....
My wife's bike didn't use the MMO, because like you, she didn't like the sound of it....
My bike used an ounce or so every fill up.
Both bikes were ridden by me (to keep the mileage close) and on the same roads and speeds etc.
I'll let you figure out which one was mine, and which one was hers.
I run 2 ounces (5 hour energy bottle) of MMO in every tankful in the ST.
Both piston(s) were just wiped off with a red shop rag, and have not been cleaned further.

 

[OldMcClelland]

wow. certainly a convincing N of one, though!

 

[sky.high]

@Igofar sure looks impressive, did you take any measurements, was the piston/rings/cylinder/valve wear different between the two?

 

[W0QNX]

That’s why I don’t waste money on specialty plugs.
Yours look good because you ride your bike.
Run a couple oz of MMO through your fuel and that will clean up #4.

I've been pouring it in when I remember ever since I read "you approved" a couple years back!

 

[STRider]

Regardless, when I see Marvel Mystery Oil and Sea Foam in the same sentence, these images come to mind...

 

[Larry Fine]

I used to love Beanie and Cecil.

 

[aldntn]

Will MMO keep valves clean in port injected engines?

 

[forestfarm]

a picture is worth a thousand words......just ordered a gallon.I want shiny pistons too

 

[Igofar]

@Igofar sure looks impressive, did you take any measurements, was the piston/rings/cylinder/valve wear different between the two?

Neither piston or rings were out of spec. I was just throwing wrenches and parts at the bikes because I was replacing the cylinder base gaskets.

 

[Andrew Shadow]

...... and decided to replace the piston's at that time, just because....

Neither piston or rings were out of spec.

I have to ask- Why replace a piston for no reason?

 

[Igofar]

I have to ask- Why replace a piston for no reason?

Because I had to pull the cylinder anyway, and had several boxes of pistons in the cabinet
I was running the little 190cc thumpers back and forth to work each day at 65mph and thought they deserved it.

 

[Andrew Shadow]

I hate to tell you Larry, but that's still replacement for no reason.