Stuttering at full throttle

[Rainer]

Hi, last week I ride aprox. 100 km with a stuttering motor, esp. when I give full throttle. There was no motor warning light or a failure stored in the ECU. I have checked all sensors and actors via the diagnostic mode, everything was fine. The only issue are totally rusty and wet spark plugs and coils.
Did anyone has the same problem with a stuttering XT ? Can the rusty spark plugs be the problem ?
Rainer
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[Dirt_Dad]

Are you running with the clutch mod? There are reports that WOT with the mod will messing up the timing of the bike, anything below WOT is fine.

 

[autoteach]

It does look like you have some moisture in there. I would clean out the spark plug holes, the head drain holes, and replace the plugs. Also, make sure that you don't have a worn coil as well. This is evident by the spring wire clamp that grabs the top of spark plug. to make a connection. I have seen this a bunch on single cylinder bikes

 

[Karson]

It does look like you have some moisture in there. I would clean out the spark plug holes, the head drain holes, and replace the plugs. Also, make sure that you don't have a worn coil as well. This is evident by the spring wire clamp that grabs the top of spark plug. to make a connection. I have seen this a bunch on single cylinder bikes

This. I'd put some good quality dielectric grease inside the coil boots on reassembly and see if that fixes your issues.

 

[Rainer]

Hi,
after cleaning the spark plug holes and installation of new sparks, the problem was gone.
I have written toYamaha Europe and explained them the problem. They told me to clean also the drain holes for the spark plug holes.
Did the XT have such drain holes in the spark plug holes ? i have searched at the outside of the motor but I did not find any drainhole.
Rainer

 

[Big Blu]

How many miles you got on the spark plugs?

Changed mine today at 16 K miles, seem the bike's a bit smoother under load.

Regards, Paull