Spark plug

[Sgt.harper48]

Any thoughts ??? Bike quit on me today after about 10 mins of riding. Was accelerating moderately in third going to fourth and it started losing power and just shut off. No clanking or metal knocking sounds or anything that would lead me to believe the motor is in trouble so I assume plug or fuel delivery issues.....again


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[Sgt.harper48]

Replaced with an iridium and it fired right up. Any hard acceleration in 3rd gear or higher and it starts dying and shutting off.

[C George]

Wow ,,,, to see a ground electrode that hot in a two stroke is pretty rare, especially to see how dark the center porcelin is.

If you look up into the plug , does the porcelin look a lot more tan towards the top ??

Something is breaking down under a load as you commented.

[C George]

It has signs of pre-ignition but then I don't understand why it would want to shut down.

Did you happen to mix up a new batch of fuel before this happened ?? Pump gas , you NEVER know.

[Sgt.harper48]

Yes brand new non ethanol 90 with yamalube 2R @ 32:1


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[Sgt.harper48]

Put stock jetting back in all new lines after thoroughly cleaning tank and petcock as well as carb again. I just don't understand this stuff. I'm seriously either going to send it to the dealership or sell it I just don't know anymore.


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[6 Riders]

Have you replaced the gas cap breather hose? Those get soft and collapse under vacuum causing a starvation issue.

[Sgt.harper48]

I'm not running a vent hose on the gas cap


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[chippy]

Looks like a fuel delivery issue to me. Float level, plugged jet, air leak, tank vent, petcock filter ???

[Slick_Nick]

I'm not running a vent hose on the gas cap


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This is suspect to me. Make sure it's not plugged that is a vital piece of the puzzle.

[Sgt.harper48]

Here's a better look down into the plug


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[C George]

Put stock jetting back in all new lines after thoroughly cleaning tank and petcock as well as carb again. I just don't understand this stuff. I'm seriously either going to send it to the dealership or sell it I just don't know anymore.


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I understand the discouragement but it's awefull easy to have patience from the dealer end when their billing out $60-$80 an hour.

That ground electrode color is really throwing me off ??? I'd double check the gas cap by attaching a hose and see if you can easily blow air threw it.
I'd also disconnect the fuel line from the carb and see if you can blow compressed air back up threw the petcock.
Or I guess you could just let the gas run out the hose and make sure your getting a good flow.

The plug center electrode looks fairly normal from what I can tell from the picture.

I'm sure you'll find it's a minor item thats causing this.

[Sgt.harper48]

Dealer billing here is 99 an hour [emoji52]. And fuel flow to carb is constant. Will check more on the cap in a bit


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[C George]

Put stock jetting back in all new lines after thoroughly cleaning tank and petcock as well as carb again. I just don't understand this stuff. I'm seriously either going to send it to the dealership or sell it I just don't know anymore.


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What did you have in it for jetting when you removed this plug ?

Whats the replacement iridium plug look like ? Same type of coloring ?

Being a iridium shouldn't effect the plug reading at all.

[Sgt.harper48]

Stock jetting 160 and 48 and I'll pull the iridium plug and post a picture in the next hour.


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[KDXGarage]

coolant level?

[C George]

+1 Jason

EXactly what I just found from Google.

Antifreeze deposits on plug with cause yellowish deposits.

Maybe a head gasket starting to seep under hard acceleration

[Tioli]

All the advice sounds good to me.

Another possibility is Check all your electrical connections something may be getting hot then separating

[C George]

Stock jetting 160 and 48 and I'll pull the iridium plug and post a picture in the next hour.


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What was the jetting before you put it back stock ?

[Sgt.harper48]

It was 155 and 45 which I believe made it leaner


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