Front Cylinder Running Leaner than Rear

[Th3InfamousI]

I know I may be splitting hairs here, but I was curious if any of you other guys have noticed that your front cylinder runs leaner/hotter than the rear? I would have imagined the opposite as the front cylinder receives the bulk of the cooling.

I added a D&M Spike and FSD Exhaust a few weekends back I got about 600 miles on the bike in the last two weekends, the bike is running great! No coughing/sneezing, etc. I pulled the plugs just to check the color and noticed that the front cylinder was a hair whiter than I would like but the back cylinder was a nice golden brown.

Anyone else in the same boat? Any ideas as to why it's burning uneven?

FYI - Running 31 Inter and 78 Main, and like I said before no issues with the bike. Not sluggish or anything snap throttle and hold on.

As you can see in the below pic the plug in the left is from the rear cylinder and looks good from my eyes, the front however slightly lean?

 

[stlmikie]

No picky.

 

[Th3InfamousI]

No picky.

Really? It's there for me...here is the link

http://i1190.photobucket.com/albums/z444/th3infamousi/IMAG0852.jpg

 

[stlmikie]

It's there now. I don't know why it didn't show the other day . That does seem to be somewhat common. I've read several threads about it. There were even a couple reasons given but they slip my mind. Unless it is totally chalky white I think it is safe. If you're in danger if burning it up one of the guys would say.

 

[Th3InfamousI]

It's there now. I don't know why it didn't show the other day . That does seem to be somewhat common. I've read several threads about it. There were even a couple reasons given but they slip my mind. Unless it is totally chalky white I think it is safe. If you're in danger if burning it up one of the guys would say.

Yea, it doesn't look too bad. It's definatly whiter than I would like but I dont think its damaging lean.

I am wondering if its because with the new FSD pipes the front pipe is significantly longer than the rear (almost double length). So the shorter pipe will run richer with less backpressure. (That is my understanding from a few posts) Could be way off base though.

 

[V]

Mine are a bit differnet as well, richer on the rear cyl. The type of intake you are running can also make a difference.

 

[MARV]

Turn the spike up then check it again

 

[Th3InfamousI]

Turn the spike up then check it again

spike is already up....

[/IMG]

 

[erldawg]

With a carb it would be very difficult to change the flow to one cylinder. Have you checked for vacuum leak? As an alternative you could put a one range cooler plug in the front....

 

[Sven]

The more porcelain, the hotter the tip can burn carbon off. The faster start is the hotter plug.
The less porcelain, the colder the plug. The harder to start, cooler when running is this plug.

Follow the black line to almost where it stops up inside the plug body and end of porcelain. There is where you read the ring around the bottom of that area. You have the heat at the tip of the porcelain cleaning that surface so it does not carbon up and can't transfer the jump of the spark to the side electrode.

The front head could be burning more efficient, who knows? What I hear is that the rear cylinder does not receive the cool hit like the front cylinder. If that is true, then the front plug should have come out of the rear plug, but seems that is a falsehood. Seems, if is a heat-sink, then the temp is the same in each barrel if both receive the same fuel amount? Blow air to both cylinders at the same time? You would now have to guess, one cylinder outperforms the burn control? :2thumbs:

 

[Sven]

Now, exposed is the true running condition of the engine. You do not read the tip of the plug. Notice how white the tip is. Notice how you read way down into the porcelain to read the way the engine is running in that brown ring.

Ideal conditions for racing is gray. No gray, no HP. Tan sets you back on the trailer = Why did you ever show up with that tune of a, "It ain't even close!"

[does the moon walk icon]

 

[2004BC]

The more porcelain, the hotter the tip can burn carbon off. The faster start is the hotter plug.
The less porcelain, the colder the plug. The harder to start, cooler when running is this plug.

Follow the black line to almost where it stops up inside the plug body and end of porcelain. There is where you read the ring around the bottom of that area. You have the heat at the tip of the porcelain cleaning that surface so it does not carbon up and can't transfer the jump of the spark to the side electrode.

The front head could be burning more efficient, who knows? What I hear is that the rear cylinder does not receive the cool hit like the front cylinder. If that is true, then the front plug should have come out of the rear plug, but seems that is a falsehood. Seems, if is a heat-sink, then the temp is the same in each barrel if both receive the same fuel amount? Blow air to both cylinders at the same time? You would now have to guess, one cylinder outperforms the burn control? :2thumbs:

Nice chart. Good info! THANKS! I appreciate it!!

 

[Peckerwood]

Interesting. My front cylinder seems to be burning richer than my rear on the last set of plugs I used (Champion r n 12 y c, as recommended). Pro auto mechanic friend of mine says that it is possible to get a bad brand new plug from time to time, and it has indeed happened to me in the past. He advised me to change them and get a new read after a short bit of riding. Might work for you also?