Originally Posted by BergDonk
More air and more fuel. At closed throttle I'd expect the relationship to be fairly linear, still whatever works. As we are routinely told, they all seem to be a bit different with final settings and there is like no identical combination of airbox and exhaust mods out there once they aren't stock. For a simple carb, the BST40 seems to create grief for some, and works great for others.
You can have your mid 40s + too. Mid 30s + are more than enough for me here. As the temp rises, the air density gets less, so less oxygen on a hot day compared to a cool one, assuming constant pressure, which isn't necessarily the case either. Its also why I richened my needle a clip from where it seemed not too bad, plus I'm at 800m and need it to work OK at sea level. My previous settings with the EMP were OK up and down, and my main is the same. Gotta ride now to confirm it all.
Something like that...
I've had excellent results with a Holtzman ATACC fitted to the FCR on a DR-Z pre-set for 0C base temperature and set-up for 0m base altitude. Needle and jets are sized for 0C and 0m and the ATACC takes care of my 0-45C temperature and 0-800m altitude range. It has also allowed economical part throttle cruise mixtures at my more common 300-500m 20-35C ranges without the risk of burning up a piston on a freezing Lake Eyre morning and the engine isn't running fat and thirsty as the day heats up on the climb out of the hole. Mixtures are always within a couple of points of where they should be on the WBO2.
BTW, once the ATACC has been set-up for base altitude and temperature jetting can be tuned at normal altitude and temperature. For my purposes it is desirable to tune at about 400m and 25C with the ATACC connected for the best overall result.
The downside is that it is quite an expensive little device, but for the amount of head banging it eliminates it is IMO worth it.