Discolored Header pipes - running lean?

The number 3 and 4 pipes on my new-to-me '72 Z1 are colored gold nearest the cylinder head but 1 and 2 are normal chrome ( the bike has a replacement 4 into 4 system ) so can I presume that it have been running lean at some point? I checked the air screws and they are one and a half turns out. What else could cause it to run lean?
Thanks,
Kevin

An open header flows more causing your A/F mixture to lean out. Jetting changes in all circuits are likely.

The first thing to check would be fuel level. Always do that first. Then check timing. Then check sinch. Now your ready to jet accordingle. Go by what the plugs tell you.And yes, gold pipe is lean symptom.

are you sure the header has been on the same bike the whole time?

leon

when I bought the bike it had been "restored" and the never run. The pipes were new.
kevin

Yorkie wrote: The number 3 and 4 pipes on my new-to-me '72 Z1 are colored gold nearest the cylinder head but 1 and 2 are normal chrome ( the bike has a replacement 4 into 4 system ) so can I presume that it have been running lean at some point? I checked the air screws and they are one and a half turns out. What else could cause it to run lean?
Thanks,
Kevin

If not already done, could also also check for possible air leak (for whatever reason) at number 3 and 4 carb holders, which leak is often accompanied by a "racing idle" issue.

Presumably fitted with stock air-box and stock-type paper filter, to rule out any pod-related issue.

Good Fortune!