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To expand on the temp change issue:

Air density is affected by temperature (as well as elevation but that's not the topic here).

The ideal (stoichometric) mixture is a 14.7:1 ratio of Oxygen to Gasoline*. The atmosphere contains 'X' amount of oxygen along with various other gasses at any given volume.

If you seal off a container of air (say, a tin can), and heat it, the gas will attempt to expand, but being trapped in a rigid container, it will only be able to build pressure...the density remains the same because the volume remains the same. Place the same amount of air in a flexible container (say, a balloon) and heat it, and the container will change volume allowing the gas to physically expand (lose density).

Inversely, if you run the same experiment but chill the containers instead of heating them, you get the opposite effect on the balloon...it shrinks (reducing it's volume) as the density of the gas inside increases.

Now, to apply this to a carburetor.

The mechanical fuel metering system in a carburetor relies upon air pressure differentials to pull fuel into the airstream as it passes through the throat of the carburetor. The carburetor has no way of measuring air density, only air volume as a byproduct of the Venturi effect of the air passing through the carburetor.

For any given volume of air, the density (read: concentration) of oxygen molecules will decrease as temperatures increase, and vice-versa.

So as temperatures drop, the concentration (density) of oxygen molecules for any given volume of air passing into the engine will increase, resulting in a 'leaning' effect...more oxygen molecules added to the same amount of fuel (with the opposite happening as temperatures increase). The greater the temperature change, the greater the effect. Eventually the distorted air/fuel ratio will become noticeable as a change in engine performance.

Generally this temperature induced distortion can be fixed with just a twist of the mixture screw. You shouldn't have to re-jet unless you run into severe seasonal temperature extremes...like my cabin in Montana which can swing from +38c in the height of summer to -40c in the depths of winter.


Too-long, didn't-read version: Yes, temperature CAN affect mixture ratios (carb tune), but in general it's nothing a little twist of the mixture screw can't resolve.


* I have always found it interesting that the Stoich. ratio for gasoline is essentially the exact same number as the atmospheric pressure at sea level (in PSI)

That routing would be ideal, so long as you can ensure there is no vacuum leak where it connects to the manifold.

I wonder if the Koreans are ever going to try breaking into the bike market like they did with Hyundai, and Kia in the car market.

(I'd love to see a bike analog to Hyundai's 250hp 3.8l rear-wheel-drive Genesis coupe)

For summer cooling:

Small cooler
Ice
Small 12v pump
Clear aquarium tubing
'Sacrificial' riding jacket

Some creative tailoring should allow you to stitch the tubing into the 'core' areas of the jacket. Hook up the tag ends of the tubing to the pump and have it circulate the cold water from the ice in the cooler (strapped to the luggage rack) through the jacket and back to the cooler.

Top off the ice when you stop to top off the tank.

When you get off the bike the only thing you lose when you 'unplug' from the hoses is a bit of water. You could even carry a couple of golf tee's around to plug the hoses from the cooler and to keep the jacket from draining (read: having to wait around for the jacket to drain so you're not leaving water dribbles everywhere).

Definitely LED. The light output is directional (up), the 'bulb' looks clear until lit (when it shines red), and the output does not fluctuate or pulse at idle the way the incandescent head/tail lights do.

Now put a fairing on it and see what you can get for milage!