Header length

I need your help guy's. i have my kz900's head off and noticed that i am getting reversion stains into the intake tracks . the odd thing is that they are not all the same.
I just measure the Kerker pipes individual lengths and got strange results.#1= 31", #2,3= 31 3/4" , #4= 30".
Can u guys that have a header laying around (any kind) measure the pipe lengths with string and a tape measure and let me know the results please.
I'm curious to know if this is normal?
This is #1

#1,2

#3&4

1 3/4 diferance in length is not bad for a aftermarket header have seen alot worse.
wouldn't have thopught it was un-equel legnth that has cuased the staining but not sure what has. my guess is bad valve seats/clarances and its burning past them.

This could be caused by cam timing?,cam size? and exhaust. Most pipes don't have equal lenght tubes. I would think cam chain wear. The more streach the cam chain has, the more the cams are retarded. It could be the later intake closing that is giving you the problem. I don't know your cam timing or size or baffle.

I am not so sure its reversion, are the seals on the intake valves good, maybe that they are laking a bit more oil down the guide.

All my head pipes are the same length on my Yoshimura header. I'm thinking it has to do with the valves or valve seals though.
Mark

i put a new cam chain ,valve seals guides, and valve job. the cams were timed to 110 lobe centers. the chain did stretch. I only had 700 miles on it. the rings did not seat, and the motor smoked.
i rechecked the LC's and the intakes changed to 112 but the x stayed at 110 lc.
I noticed the new valve seals have gone hard already. They were in for 2 seasons and only had about 2000 miles on them.
They were aftermarket seals. i just ordered OEM Kawi seals. I just thought it was odd that the staining was not equal on all 4. if it was the seals , then that may explain it. #1 was the best for some reason. i just thought it may be a dif in back pressure from the dif pipe length's?:side:

An inch and a quarter really won't make that big of a difference in header length, especially when you consider that the inside two pipes probably stay slightly hotter making them act shorter.

Becker wrote:

An inch and a quarter really won't make that big of a difference in header length,

The MAC pipe for my twin is probably more like six inches differences between pipe lengths. The RH pipe goes straight down and back and the left one goes down and crosses over to the RH side. Not even close to balanced.

Thats interesting.I'm open to opinions on what may cause this differance in coloration. do u think it would have anything to do with carb sync? it seems to a push back through the intakes from the cams overlap cycle.

your always gonna see some residue in the intake from the valve over lap as you say, the color comes from oil being burnt in the cyl, either from valve seals, or rings, I really wouldnt worry about it as long as the plugs look good and the carbs are set right.