I went with drilling my stock exhaust to get a slightly louder sound. Loved it at first. Then started realizing my headers are getting blue and I DO NOT rev the crap out of my bike. Basically means it's lean. I've heard of this happening to some, and then not to others. And now it makes me worried about running too lean. I don't have he money for an exhaust system and a ECU flash or any other fuel controllers. Are there cheap solutions to plug the holes I drilled? Buddy of mine can weld and told me he can do it for free, but wanna see what other quicker options there might be. Or is the welding the best option? I can't see how the welding could possibly happen, is the problem

Mine turned blue before I drilled it.

Ah so maybe it just comes lean from factory. Heard that, wasn't sure though. I'll have to get some type of fuel control change anyway then

Are you able to take pics of the header and post them?

I will tomorrow whenever I remember

Well here are two pics that were taken from afar and I zoomed into, I can take better ones tomorrow if these aren't good enough
 

Dont pay to much attention to pipe colors..many variables can color a pipe...drilling the stock exhaust out will not lean it out like ppl think it would...

Looks fine, but if you are going to try and plug holes, welding is about the only correct way to go.

Patches will be a good name for your bike if you haven't named it yet. I joke, hee hee! P-)
 

How big are the holes? Maybe try some short screws or bolts. But don't want them falling out under your tire...

Why would one pipe be blue and the other mostly normal?

They look pretty similar to me. The brake side pipe may have slightly more heat at the bend due to slightly dissimilar flow characteristics.
 
If your concerned, an infrared temp gun would reveal any large difference in heat between the two cylinders.
 
It can be hard to keep headers from tempering (turning blue). Exhaust gases are pretty hot.

Mine is stock and by 1000 miles pretty blue; and shoot, mines never ridden very hard!  I don't think you can make THAT much difference by simply drilling a few holes, as is typically done.

Before I replaced my stock exhaust it had turned blue by 2500 miles. I think mine was mostly due to Texas heat and getting stuck in traffic, that's a quick way to change exhaust colors.

I remember a friend's Triumph pipes getting blue right away. He babies his.
His choke was mostly off, because he rode it in summer.
Turns out it's just lower quality steel used in the pipes.
Cheaper, but good enough.
The alloys that prevent decoloration cost a lot more..

Just like my old R-bike's bikes (which blued in the 1st 30 miles), these are likely single walled pipes - done to keep the weight down. Exhaust gases are HOT! Even if they were a high grade of stainless (and they are stainless, not chromed like those old BMW pipes) , the headers would change color and even rust a touch - due to that exhaust heat.
 
Those pipes look just like mine w/no extra ventilation drilled in 'em. Perfectly normal imo.

I was a little surprised when I measured the Yamaha headers at .037" thick. That is quite thin.  Normally 304 stainless is used down to .049" thick. 321 stainless, the better alloy for handling heat, is used for .037" headers. And then the wall gets thinner at the outside of the bends where the material is stretched. Thinner material will surely blue easier, so what you are seeing is normal.