yet another valve adjustment question

So I checked my plugs after a hour ride with head temps by plugs at 340:wtf: got home pulled plugs and they were very white showing very very lean. Tonight I will be bumping up from a 145 main to a 147.5 and see what happens. Should I add another needle shim aswell to be safe or just change main and test?
Main jets are only going to make you 3/4-full throttle richer. I would look at you pilots and needles to get it richer. Wonder if that paint on the motor is also a part of it.
That's what I'm thinking. Let me bounce a idea off of you. What if I sanded all the paint off of the fin faces on the jugs. Would that help dissapate heat intern helping cool the engine? Also bike started backfiring at higher rpms indicating the main jets.
The only part that would really need it would be the head. I know there is types of engine paint that won't hold heat so I would look into that. With those type of head temps I would not be driving it at higher rpm's (6k+) till you get the temps down at normal rpm's. I would also look into your timing being to advance. Have you moved the pickup coil on the cam at all? Larger mains also may be needed.
If you haven't touched it don't worry. Your bike is electronically controlled.
I would just bump everything you another size and shim and go from there.
Also I was wondering could I have set my exhaust valve clearences to tight intern trapping exhaust gas in the heads causing excess heat or is that something that would be very noticeable?
That is possible also. Something also you may want to check. Exhaust valves should be .007" cold. intake .004 with a fit you can slide out with only just a slight drag.
So bumped pilots up to 47.5 and mains up to 147.5 and surprisingly dropped my temps by 20°. Didn't mess with the slides. So I'm thinking recheck the valve clearances and go up to 150 if I need to. Another question. Since I have no mufflers just baffles, should I try and make a lollipop for each turn out to add some extra back pressure? Do you think that would be benificial?
I was trying to adjust my valves today since i was doing a full tune up anyways.

but i couldn't lose the valve covers. i have the yamaha 17mm wrench, but at one point after spray wd-40 around the edges it chipped the cover bolt.

how can i get these off? i've taken them off before, and i'm pretty sure i didn't overly tighten
Make sure you have a well fitting wrench on it and use a breaking bar. Next time when you put them on use a little never seize on the cap.
And when tightening the caps, use a stubby wrench or hold the long wrench as close to the end you are using as possible to reduce your leverage. Tighten the caps just enough to squeeze the o-ring. You should be able to feel it. If you can't, either the o-ring is no good, or you are. Do not think "it is going to fall out unless I tighten it to the point of squealing". Because once it squeals, you are done...

Keep in mind the caps were originally installed by a little Japanese woman on the assembly line. Not a Sumo wrestler...
thanks for the advice, going to pick up a breaker bar today and some lub. i don't remember if there was even an o-ring on mine, which kind of explains why they're slightly stuck now.

did the xs360 valves have o-rings?