Weather & Tuning.

So here in good ol' Boise Idaho, we have a pretty big temp swing throughout the day in the summer. At 8 AM when I ride to work it's around 70 degrees, but at 5 PM when I ride home it's around 100. The difference in how my bike runs at 70' and 100' is super drastic.

When it's 70', I'm super super lean. Like obnoxiously lean. At 100' it runs pretty close to perfect.

A) Wondering if this is normal or not?

Aside from adjusting my needle when I leave for work, is there anything I can do to combat this!? (Because adjusting my needle twice a day doesn't sound convenient)

Current set-up:
KZ400
2-1 manifold
single VM34 carb
POD filter
Pilot jet: 25
Main Jet: 140
Air screw: +/- 1 turn out

Personally, I'd rather have it run rich at the hot part of the day, since the richer fuel mixture runs a little cooler. Based on that, I'd suggest that you rich it up a little across the board.

As to normal? I'm not sure; it does sound s little extreme, but you are going from a really cool engine early in the morning (probably even cooler than 70) to a lot warmer. Sitting in the sun on a 100 degree day, the engine's probably closer to 140 or 150 inside.

There's a lot of physics going on here - fuel reacts differently at higher temps, air is thinner at high temps, humidity is considerably different at temp, Boise isn't at sea level, etc.

Yeah... Makes sense. I think I'll richen up the main considerably and see what happens. However I'll probably leave the pilot at 25 as I went up to a 30 last night and it made it really choppy at low RPM's. The 25 at least allows for smooth cruising.

I started at a 160 on my main and have gone down from there all the way to the 140 in an attempt to make my plus less black. However I think I'm just going to have to deal with black plugs. So long as I'm not fouling them out I guess there's no harm done?