3 plugs - perfect tan color, 1 plug - dry fluffy carbon

That plug is fuel fouled, not oil fouled. Squirrellyman has a point. Low/weak spark will not burn all the fuel properly and foul plug. Swapping the coils is a quick test. Possible bad plug wire. Swap that too. Check CDI box connections also.

If all that checks out then it's back to the carb. Possible wrong pilot screw needle or damaged?? Is this happening at just idle or are you road testing?

 

Swap coils/plugs to suss out possible electrical problem, could be just a fouled out plug like said above.

 

With that plug being dry all the time you may not be getting any fuel to the cylinder. Pull the plug wire off that cylinder and run the bike for a minute. Then remove the plug and see if it is wet. If it is still dry, no gas!

 

Check your spark while the wire is off by putting a plug in the wire and grounding it against the engine. Turn it over and look for spark.

 

A big, fat, blue spark, not a weak orangeish one.

A healthy ignition coil should throw a spark about 7mm to ground.

 

Spark gap checker works well in these situations.

 

Yea....telling your friend "here hold this a second"..................

 

That's the best test.......nothing like a verbal conformation of spark strength!

 

Ok swapping them coils now. Haha nice button

 

The spark on the problem child cyl is throwing about 7mm to frame, but its lookin orangeish. Bright daylight however. The adjacent cyls spark appears to be the same, but that plug is yummy. Will swap coils now. Do coils fade out when they are spent? Ignition wires fade as well?

 

Grey750f this is happening during road test and idle. Took the bike out for a all day flogger and the problem plug went from dry fluffy black to wet gassy black

 

I doubt it's the coil. Because one coil fires to different cylinders. Your only having problems with one. So it's either the plug, plug wire or resistor in that plug wire end at the plug,which sounds like you have a good spark. It takes three entities for combustion. Fuel, which you are getting, spark ti ignite , which you have and compression. You mentioned new rings. Were the cylinders honed properly? All rings installed right? Does that cylinder have compression and how much?

 

Swapped 2 coils & wires, problem no follow. Cylinders were honed by the best race shop in town bar none. Pistons were teflon coated and I installed new rings. I was super meticulous about this...however I very well could have screwed pooch on this cylinder. The gaps were in triangles from each other and could have moved upon install. Ring placement can effect compression completely..correct? Could it be the bike was beat to shit before I bought it and the cyls were worn past spec. All cyls would be showing symptoms instead of just one? The V4 is damn tough..this common?

 

duh improper cyl test. will get at tomorrow.

 

It takes a bit of riding to get rings proppaly seated, but if your mechanic didn't check the ring END GAP, something coulda screwed up.

When do you plan a compression test ?

 

Thursday I will get a solid comp test done. Rings have about 9k on them. I rode her hard right out of the gate for the first 20 miles then changed immediately. Then a few changes around 2-500 mi. END GAP...now I recall not really giving that eagle eye for some reason. Prolly cuz I was fried from obsessing on crankcase for a week. If the gap is too small...compression issues.... doink :twitch:

 

B4 replacing rings you need to measure the cylinder diameter to see that's it's still within proppa specs.

Also, you need to place each ring squarely into the cylinder about 1" down and measure the ring end gap with a feeler gauge.

The most likely thing to go wrong if things are not correct is a ring with insufficient end gap expanding with heat, cracking, loosing compression and scoring the cylinder wall.

 

Precisely what I needed to know squirrelman. That proceedure was not done. I reealy hope I am lucky. Doing comp test now.

 

I now recall dude at racing shop measuring I.D. of cyls. He would have not proceeded if they were worn past 70.10mm, so good there.