Topic: Plug reading

[Massless]

Hello. Working on my CB 550 F and learning to read plugs. would anyone like to give me their opinion about what's going on and the condition of each cylinder based on this picture? Cylinder 1 is the left and 4 to the right. Overall it runs pretty good it seems like a little bit flat on the top and some slight popping when letting off the throttle after it's very warm.

[mj1176]

I'm no expert, but 2 and three look ok to me. That light brownish color is what you're looking for. The bright white one cylinder 1 and slightly less but still brighter cylinder 4 indicate a too-hot (i.e. lean) running condition. Again, not an expert. But I have the same bike and these look pretty similar to mine.

[540nova]

1- slightly lean
2- slightly rich
3- good
4- slightly lean


1974 CB450, 2006 CBR1000RR

[Massless]

If all jets are the same and clean and clear, could float height contribute to 1 and 4 running lean? The carbs are rebuilt and synched running 110 mains 38 slow and velocity stacks. overall it does run pretty smooth but it does seem slightly lean at times. Clip is on the 2nd notch

[Massless]

I struggled getting the float height adjusted so it could be somewhat out of whack. Set to 22 but one overflowed at that setting so I had to compensate by lowering it .